MappingUVs

Mapping UVs

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Contents

Chapter 1

UV mapping overview . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction to UV mapping . . . . . . . . . . . . . . . . . . . . . . . . 1 Creating UVs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Viewing and evaluating UVs . . . . . . . . . . . . . . . . . . . . . . . . 4 UV mapping tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 UV Texture Editor overview . . . . . . . . . . . . . . . . . . . . . . . . 8 UV sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Chapter 2

Mapping UVs . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Planar UV mapping . . . . . . Cylindrical UV mapping . . . Spherical UV mapping . . . . Automatic UV mapping . . . . User-defined UV mapping . . Confirm UV placement . . . . Transfer UVs between meshes .

Chapter 3

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Editing UVs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Display UVs . . . . . . . . . Select UVs . . . . . . . . . . Display a subset of UVs . . . Move, rotate, and scale UVs . Dolly or track within the UV

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Display a texture behind the UVs . . . . . . . . . . . Delete UVs . . . . . . . . . . . . . . . . . . . . . . . Update a texture image after UV modification . . . . Use the UV Texture Editor grid . . . . . . . . . . . . Save an image of the UV layout . . . . . . . . . . . . Modify UVs using the UV Lattice Tool . . . . . . . . Modify UVs using the UV Smudge Tool . . . . . . . Separate and attach UV shells . . . . . . . . . . . . . Display overlapping UVs . . . . . . . . . . . . . . . Display UV winding order . . . . . . . . . . . . . . Layout UV shells . . . . . . . . . . . . . . . . . . . Map border UVs to a square or circle . . . . . . . . . Straighten border UVs . . . . . . . . . . . . . . . . . Relax and untangle UVs . . . . . . . . . . . . . . . . Unfold a UV mesh . . . . . . . . . . . . . . . . . . . Example: Lay out a UV shell using unfold and relax . Flip or rotate UV shells . . . . . . . . . . . . . . . . Copy UVs and color attributes between polygons . .

Chapter 4

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UV sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Create UV sets . . . . . . . . . . . . . . Switch between UV sets . . . . . . . . . Duplicate, rename, or delete a UV set . . Assign a texture to a UV set . . . . . . . Copy UVs from one UV set to another . Working with per-instance UV sets . . . Edit NURBS UVs . . . . . . . . . . . . .

Chapter 5

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. 83 . 84 . 84 . 85 . 86 . 87 . 93

UVs menu reference . . . . . . . . . . . . . . . . . . . . . . . . 97 Create UVs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Create UVs > Planar Mapping . . . . . . . . . . . . . . . . . . . . 97 Create UVs > Cylindrical Mapping . . . . . . . . . . . . . . . . . 99 Create UVs > Spherical Mapping . . . . . . . . . . . . . . . . . 100 Create UVs > Automatic Mapping . . . . . . . . . . . . . . . . . 102 Create UVs > Create UVs Based On Camera . . . . . . . . . . . . 106 Create UVs > Best Plane Texturing Tool . . . . . . . . . . . . . . 107 Create UVs > Assign Shader to Each Projection . . . . . . . . . . 107 Create UVs > Create Empty UV Set . . . . . . . . . . . . . . . . 107 Create UVs > Copy UVs to UV Set . . . . . . . . . . . . . . . . . 108 Create UVs > Set Current UV Set . . . . . . . . . . . . . . . . . 108 Create UVs > Rename Current UV Set . . . . . . . . . . . . . . . 109 Create UVs > Delete Current UV Set . . . . . . . . . . . . . . . . 109 Create UVs > UV Set Editor . . . . . . . . . . . . . . . . . . . . 109 Create UVs > Per Instance Sharing . . . . . . . . . . . . . . . . 109 Edit UVs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

vi | Contents

Edit UVs > Normalize . . . . . . . . Edit UVs > Unitize . . . . . . . . . . Edit UVs > Flip . . . . . . . . . . . . Edit UVs > Rotate . . . . . . . . . . Edit UVs > Grid . . . . . . . . . . . Edit UVs > Align . . . . . . . . . . . Edit UVs > Warp Image . . . . . . . Edit UVs > Map UV Border . . . . . Edit UVs > Straighten UV Border . . Edit UVs > Relax . . . . . . . . . . . Edit UVs > Unfold . . . . . . . . . . Edit UVs > Layout . . . . . . . . . . Edit UVs > Cut UV Edges . . . . . . Edit UVs > Split UVs . . . . . . . . . Edit UVs > Sew UV Edges . . . . . . Edit UVs > Move and Sew UV Edges . Edit UVs > Merge UVs . . . . . . . . Edit UVs > Delete UVs . . . . . . . . Edit UVs > UV Texture Editor . . . .

Chapter 6

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UVs windows and editors reference . . . . . . . . . . . . . . . 139 UV Texture Editor . . . . . . . . . UV Texture Editor reference . UV Texture Editor menu bar . UV Texture Editor toolbar . . UV Set Editor . . . . . . . . . . . .

Chapter 7

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UVs tool reference . . . . . . . . . . . . . . . . . . . . . . . . 163 Move tool (in UV texture editor) . . . . . . . . . . . . . . . . . . . . 163

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Contents | vii

viii

UV mapping overview

1

Introduction to UV mapping UVs (pronounced U-VEEZ) are two-dimensional texture coordinates that reside with the vertex component information for polygonal and subdivision surface meshes. UVs exist to define a two-dimensional texture coordinate system, called UV texture space. UV texture space uses the letters U and V to indicate the axes in 2D. UV texture space facilitates the placement of image texture maps on a 3D surface. UVs are essential in that they provide the connection between the surface mesh and how the image texture gets mapped onto the surface mesh. That is, UVs act as marker points that control which points (pixels) on the texture map correspond to which points (vertices) on the mesh. Textures applied to polygon or subdivision surfaces that do not possess UV texture coordinates will not render. Although Maya creates UVs by default for many primitive types, you’ll need to rearrange the UVs in most cases, because the default arrangement will usually not match any subsequent edits to the model you may make. In addition, the location of the UV texture coordinates do not automatically update when you edit a surface mesh. In most cases, you map and arrange UVs after you have completed your modeling and before you assign textures to the model. Otherwise, changing the model will create a mismatch between the model and the UVs, and affect how any textures appear on the model. Understanding the concept of UVs and how to map them to a surface, and subsequently lay them out accurately is essential for producing textures on polygonal and subdivision surfaces when working in Maya. Understanding how

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UVs work is also important when you need to paint textures, fur, or hair onto a 3D model.

UVs and texture mapping Texture mapping polygon and subdivision surfaces in Maya differs from how you texture NURBS surfaces. For NURBS surface types, each surface mesh is defined as a four-sided square or rectangular patch that has specific U and V directions. For NURBS surface types the texture coordinates (UVs) that control the placement of a texture exist by default and are implicitly connected to the control vertices. When the control vertices get repositioned, so do the positions of the corresponding UV texture coordinates. Any textures mapped to the surface are also affected as a result. That is, moving a CV will affect how the texture map appears on the NURBS surface. For polygon and subdivision surface types, the shape of surface meshes is usually much more irregular compared to NURBS surface types. Texture coordinates (UVs) associated with these surface types do not always exist by default, and so must be explicitly created, and subsequently modified in most cases, so that the surface mesh can accommodate a texture map.

UV mapping The process of creating explicit UVs for a surface mesh is called UV mapping. UV mapping is a process whereby you create, edit, and otherwise arrange the UVs (that appear as a flattened, two-dimensional representation of the surface mesh, over top of the two-dimensional image to be used as a texture as it appears in the UV Texture Editor. The UV mapping process results in a correlation between the image and how it appears as a texture when mapped onto the three-dimensional surface mesh. UV mapping is a critical skill to master for accurate and realistic textures on polygonal surfaces. ■

You create UVs by mapping them onto your surface mesh using a variety of options. For more information see the Related topics section below.

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You view and edit UVs using the UV Texture Editor. You can display the texture image as a background image to let you more easily correlate the UVs to the texture. The UV Texture Editor provides many useful tools for laying out and manipulating the 2D representation of UVs. For more information see UV Texture Editor overview on page 8.

2 | Chapter 1 UV mapping overview

NOTE You only need to be concerned about UV texture coordinates when you want to apply a texture map to polygons. UV mapping is not necessary for creating and reshaping polygon and subdivision surfaces.

Related topics ■

Creating UVs on page 3

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Viewing and evaluating UVs on page 4

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UV Texture Editor overview on page 8

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UV mapping tips on page 6

Creating UVs In Maya, UV texture coordinates (UVs) can be created for polygon surface meshes using the following UV mapping techniques: ■

Automatic UV mapping on page 22

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Planar UV mapping on page 15

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Cylindrical UV mapping on page 19

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Spherical UV mapping on page 21

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User-defined UV mapping on page 25

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Camera UV mapping - see Planar UV mapping on page 15

Each UV mapping technique produces UV texture coordinates for the surface mesh by projecting them onto the surface mesh based on its inherent projection method. As a result, the UV texture coordinates have an initial 2D spatial correlation to the vertex information in the 3D world space coordinate system. It is this correlation between the texture map and the surface mesh via the UVs that positions the texture on the surface. The initial mapping produced via the above UV mapping techniques does not usually produce the final UV arrangement that is required for a texture. As a result, you will often need to perform further editing operations on the UVs using the UV Texture Editor.

Creating UVs | 3

The polygon and subdivision surface primitive types in Maya have default UV texture coordinates that can be used for texture mapping. However, if you modify the default primitives in any way (that is, scale, extrude faces, insert or delete edges) you will need to map a new set of UV texture coordinates onto the modified object to suit your texture mapping requirements. The best workflow is to map UVs onto a model only when the it is complete.

Related topics ■

Introduction to UV mapping on page 1

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Viewing and evaluating UVs Once you have mapped UVs onto a model you view and edit the resulting UV texture coordinates using the UV Texture Editor. The UV Texture Editor lets you view the two-dimensional UV mesh on its own or in relation to the image texture. The UV Texture Editor lets you manipulate the components of the UV mesh in the 2D view much like you work with other polygon components in Maya. In some instances the default UV projection may not appear in a manner you expect or require. In these situations you must visually evaluate, then manually edit the UV layout to rearrange the position of the UVs within the UV Texture Editor to better suit the requirements of the texture. In terms of production workflow, you typically map and edit (rearrange) the UVs once you have completed your modeling and before you assign textures to the model. How you edit the UVs for a particular polygon mesh depends on the texture mapping requirements you have. The following are some examples of situations where UVs need to be edited to meet specific texturing requirements. ■

When the image for a texture map already exists, the UV mesh (and possibly the surface mesh) will need to be modified to conform to the requirements of the image. One example of this is when texture mapping a games character and the artwork for the texture maps already exist for a known film actor, athlete, or comic book character. In addition, the image for the character's textures may be comprised of many smaller separate


images for the various components of the character on the same image (For example, sub-images of the face or head, torso, legs etc.). This method of laying out many images on a single image is commonly referred to as a decal sheet and is very efficient in terms of texture and memory usage for an interactive game application. When using a decal sheet approach the UVs must be arranged so they match up with the corresponding images on texture map as it appears in the UV Texture Editor. ■

When you want to reference the same image multiple times for a texture map you will want the UVs to lay directly on top of each other when viewed in the UV Texture Editor. This approach is useful and efficient in situations when the UVs can share the same region of a texture image. For example, if you had a brick texture that you wanted repeated on several buildings in a scene you could lay each separate UV mesh in exactly the same position within the UV Texture Editor. Otherwise overlapping UVs are generally not desirable and will produce unexpected texture mapping results. When UVs overlap you can lay them out to not overlap using Edit UVs > Layout.

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When you need to manually reassemble a UV mesh after using Automatic mapping to create UVs for a surface mesh. Automatic mapping invariably produces multiple projections for a surface mesh based on the shape of the surface mesh. As a result, the UV projections appear as many separate UV components in the UV Texture Editor. This can be problematic when you need to have a UV mesh that is one contiguous piece to allow a texture artist to paint directly on the 3D object. You can reposition and attach the individual UV components using features in the UV Texture Editor such as Polygons > Move and Sew UV Edges.

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When the shape of the projected UVs are badly distorted compared to the 3D surface mesh the resulting texture map will be compressed, stretched or otherwise distorted on the surface mesh in an undesirable fashion. There are many options for correcting these situations using features in the UV Texture Editor such features as Unfold and Relax. NOTE To create a UV mapping arrangement that works best for your model, you may need to try a variety of mapping techniques, until you find a mapping arrangement that is suitable. For more information on laying out UVs see UV mapping tips on page 6.

Related topics ■


Viewing and evaluating UVs | 5

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UV mapping tips Maya provides a number of features that let you easily create and edit UV texture coordinates for texture mapping your polygon and subdivision surfaces. The UV Texture Editor (Edit UVs > UV Texture Editor) is the primary tool for arranging and laying out UVs for optimal textures. Knowing how to arrange UV texture coordinates is an important skill to master that depends on whether you are generating a new texture using the UVs as a guide, or if you are adapting the UVs to optimally fit an existing image. The best arrangement depends on the types of textures you will apply and also upon whether you are creating rendered images or models for interactive games. A full description of UV arrangement is out of the scope of this guide but you should consider the following guidelines:

Keep UVs within the 0 to +1 texture coordinates The UV Texture Editor displays a grid marking the texture space for UVs. The working area of the grid begins at 0 and extends to 1. By default, the UV mapping operations in Maya automatically fit UVs within the 0 to 1 coordinates. While it is possible to move or scale the UVs so they reside outside of this 0 to 1 region, you should keep the UVs for a surface positioned within these 0 to 1 coordinates, in the majority of situations. When the UVs extend beyond the 0 to 1 range, the texture will appear to repeat or wrap around the corresponding vertices when viewed in the 3D scene or rendered image. The exception to this guideline is when you actually want the texture to repeat on the surface, such as a brick texture along the model of a wall.

Avoid overlapping UV shells UV points have interconnecting lines that form a shape, called a UV shell. If any of the UV shells overlap in the UV Texture Editor, the texture will appear to repeat on the corresponding vertices. In general, you should avoid overlapping UVs, unless you want the texture to repeat. For example, if you want the arms of a character to share the same texture pattern, you can place


the UV shell corresponding to one arm on top of the piece corresponding to the other arm, using the Move UV Shell Tool. Some UV projection operations often result in overlapping UV shells, but you can easily separate the shells using the Layout feature, as described in Layout UV shells on page 58.

Spacing between UV shells The spacing between UV shells is an important consideration. You’ll want to have the UV shells as close together as possible to maximize the UV texture space. However, if the shells are too close together, there is the possibility that the textures may bleed between one surface to another.

Snapping UVs You can use snapping in the UV Texture Editor to lock your transformations to existing objects in the scene. This functionality is similar to the snapping functionality in the scene view. You can use the Preserve Component Spacing option in the Move Tool settings when transforming multiple UVs to maintain their relative spacing. To snap to...

Hold

Grid intersections

x

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(In the Status Line) Other UVs (points)

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(In the Status Line) Pixels

(In the UV Texture Editor toolbar)

UV mapping tips | 7

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If snapping is on and you drag an axis manipulator (as opposed to the manipulator’s center), the manipulator snaps to the nearest point or grid intersection restricted to that axis (depending on the snapping mode). Alternatively, you can use Shift + x or Shift + v to snap to the nearest point restricted by the U or V axis respectively.

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Pixel Snapping is measured by monitor pixels. You can zoom in close to the UVs to achieve better results. This setting also affects snapping for rotating and scaling pivot locations.

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UV Texture Editor overview Window > UV Texture Editor Edit UVs > UV Texture Editor In scene view: Panels > Panel > UV Texture Editor The UV Texture Editor lets you view and interactively edit the UV texture coordinates for polygon, NURBS, and subdivision surfaces within a 2D view. You can select, move, scale, and generally modify the UV topology for a surface very much like you work with other modeling tools within Maya. You can also view the image associated with the assigned texture map as a backdrop within the UV Texture Editor and modify the UV layout to match as required.


Maya lets you easily compare what you view in the 3D scene view and in the UV Texture Editor’s 2D texture coordinate view by displaying the perspective view and the UV Texture Editor simultaneously. For example, you can select a UV within the 3D scene view and simultaneously see the same selected UV coordinate in the 2D view of the UV Texture Editor and vice versa. This is useful when you’re editing UVs and need to understand how an item in the 2D view relates to the 3D model in the scene view. For this reason, many Maya users find it invaluable to have the Maya perspective view and the UV Texture Editor displayed side-by-side when performing UV texture and layout work. You select this layout from the layout shortcuts section of the Toolbox.

UV Texture Editor overview | 9

The UV Texture Editor contains tools that allow you to modify the UV texture coordinates. For example, you can perform such actions as rotating and flipping UVs as well as cutting and sewing UVs in order to achieve the UV layout you require. You can also output a bitmap image of the final UV layout so it can be used as a background for texture creation work. There are separate menus for polygons and subdivision surfaces UV tasks. Many of the items within the UV Texture Editor are also accessible from the UV Texture Editor’s toolbar as icons. As well, some of the items that are contained within the UV Texture Editor are also available in the Edit UVs menu from the Polygons menu set.

Viewing items in the UV Texture Editor When viewing UV texture coordinates in the UV Texture Editor you: ■

use the standard camera move keys (Alt + the middle mouse button and Alt + the right mouse button) to track and dolly within the 2D texture view.

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press f in the UV Texture Editor to frame any selected items in the 2D view.

Marking menus in the UV Texture Editor UV specific marking menus are available when you work in the UV Texture Editor. This saves you time and streamlines your UV editing workflow. When


you Shift + right-click in the UV Texture Editor the marking menu shows different items depending on what components are currently selected: ■

When UV texture coordinates are currently selected the marking menu shows possible UV modification operations (for example, Relax, Unfold, Smudge Tool, and Lattice Tool are available). While the marking menu is displayed, simply drag your mouse to highlight the desired item in the menu; the item is selected as if it were selected from the related UV Texture Editor location in the menu or toolbar.

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When a polygon edge is currently selected the marking menu shows possible UV edge modification operations for the selected component (for example, Cut UV Edges, Sew UV Edges, Move and Sew UV Edges, and others).

When a polygon face is currently selected the marking menu shows possible UV modification operations for the selected UV type (for example, Normalize,Unitize, Layout, and others).

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Flip or rotate UV shells on page 79

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Display UVs on page 31

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Select UVs on page 32

UV sets You can create multiple arrangements of UV texture coordinates for a surface mesh using UV sets. UV sets are useful when an object requires multiple UV layouts for different textures (known as multi-texturing). For example, if you create a brick wall and want to layer spray paint on top, you can use one texture for the bricks and one texture for the paint using a layered texture. If the brick texture repeats but the paint texture doesn’t, you will want different UV layouts (UV sets) for each. If you are planning to pre-light the surfaces in your scene (also referred to as light baking), you’ll want to use UV sets to store the shading and lighting color

UV sets | 11

information from the rendered appearance of a polygon mesh directly on the color per vertex information for the mesh.

The main steps to set up multi-texturing are: ■

Assign multiple textures to an object’s material. These textures can be assigned to different material attributes, such as Color and Incandescence, or assigned to a single attribute using a Layered Texture node.

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Create UV sets with different layouts.

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Link each UV set to a given texture using the Relationship Editor.

Examples The following examples show UV sets used to texture a brick wall. In both examples, the UV sets are: ■

unitizedUVs—for the repeating brick texture.

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planarUVs—for the non-repeating texture.


UV sets for Color and Transparency In this example, the UV sets are connected to textures on different attributes of the material—Color and Transparency.

UV sets for a Layered Texture In this example, the UV sets are connected to layered textures.

UV sets | 13

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Create UV sets on page 83

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Switch between UV sets on page 84

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Duplicate, rename, or delete a UV set on page 84

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Assign a texture to a UV set on page 85

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Copy UVs from one UV set to another on page 86


Mapping UVs

2

Planar UV mapping Planar mapping projects UVs onto a mesh through a plane. This projection is best for objects that are relatively flat, or at least are completely visible from one camera angle.

Planar mapping typically gives overlapping UV shells. The UV shells may be perfectly superimposed and look like a single UV shell. You should use Edit UVs > Layout after mapping to separate overlapping UVs. The Best Plane Texturing Tool assigns UVs to the faces you select based on a plane computed from vertices you specify. You can select the faces you want to map before you choose the Best Plane Texturing tool, or you can choose the tool and then click each face you want to map. To map based on the best fit plane of the selection 1 Select the faces you want to map UVs onto.

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2 Select Create UVs > Best Plane Texturing Tool. 3 You click faces to add them to the selection. 4 Select one or more faces on which you want to map the texture. You cannot marquee-select the faces—you must select the faces one by one, or select the faces before using the operation. 5 Press Enter. 6 Select one or more vertices (press the right mouse button on the mesh and choose Vertex to switch to selecting vertices). 7 Press Enter. 8 Use the UV Texture Editor to view and edit the resulting UVs.

To project from a plane defined by the view 1 Select the faces you want to project UVs onto. 2 Tumble the perspective view, or track an orthographic view to look at the faces. 3 Select Create UVs > Create UVs Based On Camera.

16 | Chapter 2 Mapping UVs

To map based on a planar projection 1 Select the faces you want to project UVs onto. 2 Select Create UVs > Planar Mapping >

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The Planar Mapping Options window appears. 3 Set the following options as required: ■

Click Best Plane to position the manipulator based on the faces you selected.

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Click Bounding Box to position the manipulator based on the bounding box of the mesh.

4 Click Project. 5 Use the projection manipulator to control how the plane distributes UVs. 6 Use the UV Texture Editor to view and edit the resulting UVs.

Planar UV mapping | 17

You can also rotate the manipulator by clicking the red crossed lines, which reveals the Show Manipulator tool. Click the light blue circle around the Show Manipulator handle to activate the rotate handles.

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Planar mapping can create shared, overlapping UVs that can look like texture borders. Turn on texture border display (in Display > Polygons > Texture Border Edges) to clearly show texture borders.

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Shared, overlapping UVs can create seam problems if you paint over them with the 3D Paint or Paint Fur Attributes Tools. To avoid these problems, manually separate the UVs with Edit UVs > Layout > . Set Separate shells to Folds and the Shell layout option to Along U or Into Square.


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Projection mapping only works properly on a single object at a time. If you need to apply a projection to multiple polygonal objects in a single step, combine the objects into one, apply the projection, and then separate the parts back out. Otherwise, perform a projection on each object separately.

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When a model’s form is very organic, and you require a complete UV representation of that model for texture mapping, a planar projection can produce UVs that overlap and appear distorted. Unless you want this to occur it is recommended you try another UV mapping technique.

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Create UVs > Assign Shader to Each Projection on page 107

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Create UVs > Create Empty UV Set on page 107

Cylindrical UV mapping Cylindrical mapping creates UVs for an object based on a cylindrical projection shape that gets wrapped around the mesh. This projection is best for shapes which can be completely enclosed and visible within a cylinder, without projecting or hollow parts.

Cylindrical UV mapping | 19

1 Select the faces you want to project UVs onto. 2 Select Create UVs > Cylindrical Mapping. 3 Use the manipulator to change the position and size of the projection shape. 4 Use the UV Texture Editor to view and edit the resulting UVs.

NOTE Projection mapping only works properly on a single object at a time. If you need to apply a projection to multiple polygonal objects in a single step, combine the objects into one, apply the projection, and then separate the parts back out. Otherwise, perform a projection on each object separately.


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Create UVs > Cylindrical Mapping on page 99

Spherical UV mapping Spherical mapping create UVs using a projection that is based on a spherical shape wrapped around the mesh. This projection is best for shapes which can be completely enclosed and visible within a sphere, without projecting or hollow parts.

To create UVs using a spherical mapping technique 1 Select the faces you want to project UVs onto. 2 Select Create UVs > Spherical Mapping. 3 Use the manipulator to change the position and size of the projection shape. 4 Use the UV Texture Editor to view and edit the resulting UVs.

Spherical UV mapping | 21

NOTE Projection mapping only works properly on a single object at a time. If you need to apply a projection to multiple polygonal objects in a single step, combine the objects into one, apply the projection, and then separate the parts back out. Otherwise, perform a projection on each object separately.

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Automatic UV mapping Automatic mapping creates UVs for a polygon mesh by attempting to find the best UV placement by simultaneously projecting from multiple planes. This method of UV mapping is useful on more complex shapes where the basic planar, cylindrical, or spherical projections do not produce UVs that are useful, especially on components that project outwards or are hollow in nature.


Automatic mapping creates several UV map pieces or shells in texture space. This is fine if you are using tools that deal with UVs automatically for you, such as standard (not combed) fur and the 3D Paint tool in projection mode. If you need to work with the UVs manually, you will need to stitch the UV shells back together in the UV Texture Editor using the Move and Sew UV Edges feature. You can also specify user-defined planes for the projection of UV texture coordinates. The Load Projection option uses a polygon object you specify from the current scene. To facilitate more accurate UV projections a projection manipulator is displayed when using the Automatic Mapping feature. The projection manipulator lets you correlate the multiple planar UV projections that occur in the scene view with how the resulting UVs appear in the UV Texture Editor.

Automatic UV mapping | 23

The projection manipulator appears centered about the selected object in the scene view with blue planes that correspond to the number of planes set by the Automatic Mapping’s Planes option. A light blue color indicates that the projection plane is oriented facing away from the selected object, while a dark blue plane indicates the side of the projection plane that is oriented facing towards the selected object. The manipulator’s planes are displayed semi-transparent at a scale of 50% of the actual projection plane so they don’t fully occlude the object when using the manipulator. Red and green lines appear along the edge of each plane to indicate the corresponding U and V axes within the UV Texture Editor. You can move, rotate, and scale the UV projection manipulator just like other manipulators in Maya. Scaling the manipulator affects the resulting scale of the projected UVs in the UV Texture Editor. You can reset any transformations for the projection manipulator using the Channel Box. When a custom projection object is specified using the Load Projection option, the projection manipulator gets updated to reflect the planes specified by the custom projection. To map UVs for a polygon object using Automatic Mapping 1 Select a polygon object in the scene view that you want to project UVs texture coordinates. 2 Select Edit UVs > UV Texture Editor to display the UV Texture Editor or select the Persp/UV Texture Editor layout shortcut from the Toolbar to view the perspective view and the UV Texture Editor side by side. When you project the UVs they will appear in the UV Texture Editor’s 2D view. 3 From the Polygons menu set, select Create UVs > Automatic Mapping > . The Polygon Automatic Mapping Options window appears. 4 Set the following options depending on your requirements: ■

Set the Planes setting to the desired number of projections you require and click Project. (The more planes you use, the less distortion in the UV layout but the more shells are created).

The automatic mapping projection manipulator appears centered about the object in the scene view with blue projection planes that correspond to the Planes setting you specified. That is, if the Planes option was set to 4, then 4 planes appear on the manipulator.


5 To move, rotate, or scale the projection manipulator do the following: ■

To move the projection manipulator in X, Y, Z, drag any of the three colored arrow handles while moving your mouse.

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To rotate the projection manipulator, click the light blue circular rotate handle to make the X, Y, Z rotate handles appear. Dragging any of the three circles rotates the manipulator about X, Y, or Z.

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To non-proportionally scale the projection manipulator, drag any of the three colored box handles on the manipulator.

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To uniformly scale the projection manipulator, click any of the three box handles on the tip of the manipulator so a 3D box appears. Drag the box to scale the manipulator uniformly.

6 Use the UV Texture Editor to view and edit the resulting UVs. NOTE Projection mapping only works properly on a single object at a time. If you need to apply a projection to multiple polygonal objects in a single step, combine the objects into one, apply the projection, and then separate the parts again Otherwise, perform a projection on each object separately.

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User-defined UV mapping You can map UV texture coordinates by specifying user-defined planes for UV projection using the Load Projection option within the Automatic Mapping feature. The Load Projection option uses a polygon object that you specify from the current Maya scene. The object can form a cage around the object or be comprised of separate faces that intersect each other at its center. The Automatic Mapping projection manipulator updates when a user-defined object is specified for projection.

User-defined UV mapping | 25

Criteria for user-defined projection objects ■

The object used as a user-defined projection object must have UV texture coordinates.

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It is recommended that the projection object be comprised of separated polygon faces. That is, a polygon primitive that gets used as a projection object should first be separated into separate meshes using Mesh > Extract. (NURBS and subdivision surfaces are not valid surface types for use with Load Projection.)

In addition, it is useful to know that: ■

The UVs of the projection object determine the shape and location of the final projection mapping that occurs.

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You can translate any face from the Load Projection object along its normal with no affect on the resulting projection.

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Scaling or rotating any face from the Load Projection object will affect the resulting orientation and scale of the final UV projection. The projection manipulator updates when this occurs.

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The maximum number of polygon faces that can be specified for a projection object is 31.

To load a user-defined polygon object for use with Automatic Mapping 1 Select a polygon object in the scene view that you want to project UVs onto. 2 Select Edit UVs > UV Texture Editor to open the UV Texture Editor. The existing UVs for the object appear in the UV Texture Editor’s 2D view. 3 From the Polygons menu set, select Create UVs > Automatic Mapping> . The Polygon Automatic Mapping Options window appears. 4 In the Polygon Automatic Mapping Options window, turn on the Load Projection option, then do one of the following: ■

Specify the object in your current scene you want to have loaded as the projection object by typing its name in the Projection Object box.


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Select the object in your current scene that you want to have loaded as the projection object, and then click Load Selected. The name of the object appears in the Projection Object box. See Criteria for user-defined projection objects on page 26 above.

5 Click Project or Apply to execute the Automatic Mapping feature. The automatic mapping projection manipulator appears centered about the object in the scene view with blue projection planes that correspond in orientation to the planes of the Load Projection object you specified. That is, if the Load Projection object has 8 planes in various angles of orientation, the projection manipulator displays similarly. NOTE In some instances, the Load Projection object may cause the planes on the automatic mapping projection manipulator to appear unexpectedly offset or skewed from the object you’re projecting on. This UV offset is based on the original UVs for the Load Projection object and doesn’t affect the quality of the projection. You can unitize the UVs for the Load Projection object prior to projection so its UVs reside in the 0 to 1 texture space. While this will make the projection manipulator appear more centered about the polygon object it may not provide the UV mapping results you were expecting as the UVs will be projected similar to having explicitly specified the Overlap feature.

6 Translate, rotate, or scale the manipulator as required to achieve the UV projections you require. The projected UVs appear in the UV Texture Editor. You can observe them update within the UV Texture Editor whenever the manipulator is moved within the scene view.

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Create UVs > Spherical Mapping on page 100

User-defined UV mapping | 27

Confirm UV placement Confirming that UVs are positioned correctly for a surface mesh is critical if you want the textures to appear correctly on the surfaces of your mesh. One method of confirming the UV placement is to assign a shader that contains a texture with visual characteristics that help indicate how the UVs are mapping the texture onto the surface. When you turn on Create UVs > Assign Shader to Each Projection, Maya will assign a checkerboard texture shader to the mesh as you project UVs. This provides a quick visual indication of the UV placement.

You can use a different texture on the defaultPolygonShader. For example, if you’re going to be mapping a stone texture to many objects, edit the defaultPolygonShader to use a stone texture for previewing. You can also create your own custom 2D image using a paint or 2D image manipulation application. If you do not need to pre-adjust your texture maps, turn off Assign Shader to Each Projection. The option is off by default.

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Transfer UVs between meshes You can map your UVs to a smoothed version of your polygon model, where it may be easier to get good UVs (for example, you can smooth out wrinkles which cause overlapping UVs). Then you can use the Transfer operation to copy the mapped UVs back onto the complex original model. To transfer smoothed UVs between polygon meshes 1 Duplicate your polygon mesh. 2 On the duplicate, select the vertices you want to smooth. 3 Select Mesh > Average Vertices >

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4 Enter a value for the Smoothing Amount then click Apply. The higher the value the more smoothing. You can click Apply repeatedly to smooth repeatedly. 5 Project UVs onto the smoothed duplicate model using any of the mapping options in the Create UVs menu. 6 Use Mesh > Transfer Attributes to copy the UVs from the smoothed duplicated back to the original mesh.

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Mesh > Average Vertices

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Mesh > Transfer Attributes

Transfer UVs between meshes | 29

30

Editing UVs

3

Display UVs UVs are viewed and edited in the 2D view of the UV Texture Editor (Edit UVs > UV Texture Editor). UVs display whenever a polygonal or subdivision surface mesh is selected in the scene view. When the 3D mesh is de-selected the UVs are no longer displayed in the UV Texture Editor. By default, all of the UVs for a selected object get displayed. You can display a subset of UVs using the Isolate Select feature. For more information see Display a subset of UVs on page 33. NOTE The 2D representation of UVs cannot be displayed in the Maya scene views. To display UVs in the UV Texture Editor 1 Select Edit UVs > UV Texture Editor to display the UV Texture Editor. 2 Do one of the following: ■

In the scene view, set the selection type to object using the marking menu and then select the polygon or subdivision surface mesh. The UVs for the selected mesh are displayed in the UV Texture Editor.

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In the scene view, set the selection type to UV using the marking menu and then select any vertices on the polygon or subdivision surface mesh. The UVs associated with the vertices you selected on the mesh are displayed in the UV Texture Editor.

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Display a subset of UVs on page 33

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Dolly or track within the UV Texture Editor on page 41

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Display a texture behind the UVs on page 42

Select UVs Selecting UVs, UV components, and UV shells is critical to editing the layout of UVs in the UV Texture Editor. You can select UVs in either the scene view or in the UV Texture Editor but you can only view and edit the 2D representation of UVs using the UV Texture Editor. To select UVs in the scene view 1 Press the right mouse button over top of the polygon or subdivision surface mesh and select UV from the marking menu. UVs for the surface mesh display in exactly the same location as the vertices so you can select them in the scene view. 2 Click on the UVs or drag a marquee selection to select the UVs. The UVs are selected in the scene view. To view a 2D representation of the UVs you must open the UV Texture Editor (Edit UVs > UV Texture Editor). To select UVs and UV shell components in the UV Texture Editor 1 Press the right mouse button on UVs in the UV Texture Editor to enter different component selection modes. This works in a similar fashion to how you select polygon components with the marking menu in the scene view.

32 | Chapter 3 Editing UVs

To convert an existing UV selection to another type 1 Hold Ctrl and press the right mouse button to show items for converting one type of selection to another. For example, if you have faces selected, you can convert the selection to UVs to use the Move tool, which only works with UVs. Use the items in the UV Texture Editor’s Select menu to select various components: ■

Select Contained Faces: Selects the faces bordered the selected UVs or edges.

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Select Connected Faces: Selects the faces connected to the selected UVs or edges.

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Select Shell: Select all UVs in the shell containing the current selection. This is useful to select the whole piece so you can move, scale, or rotate it.

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Select Shell Border: Expands your selection to all UVs along the border of the UV piece.

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Convert Selection to Faces, Edges, Vertices, UVs: Converts the selection from one type of component to another connected type. For example, if you have faces selected and convert selection to vertices, all vertices connected to the faces are now selected.

Soft selecting UVs You can use Soft Selection to smoothly transform textures on your models without transforming each UV one at a time. Soft selection works by transforming a falloff region around your selected region. For more information see Soft Selection.

Display a subset of UVs By default, when you select a surface mesh Maya displays all of the UVs for that mesh in the UV Texture Editor. You can switch the UV Texture Editor between displaying all of the UVs for the current set and only showing a selected subset in isolation. This makes it easier to work on part of the model without disturbing or accidentally selecting other UVs.

Display a subset of UVs | 33

To isolate a specific subset of UVs 1 In the UV Texture Editor, if you already have a subset of UVs isolated, click the Remove all button on the toolbar. Alternatively, choose View > Isolate Select > Remove All. 2 Select the UVs you want to isolate. 3 Click the Toggle isolate select mode button on the toolbar, or choose View > Isolate Select > View Set. To switch back to showing all UVs, click Toggle isolation again, or turn off the View > Isolate Select > View Set menu item. To add to the isolated subset of UVs 1 In the UV Texture Editor, click the Toggle isolate select mode button on the toolbar to switch back to showing all UVs. Alternatively, choose View > Isolate Select > View Set. 2 Select the UVs you want to add to the isolated subset.

3 Click the Add selected button on the toolbar. Alternatively, choose View > Isolate Select > Add Selected. To remove UVs from the isolated subset 1 In the UV Texture Editor, select the UVs you want to remove from the isolated subset.

2 Click the Remove selected from isolation button on the toolbar. Alternatively, choose View > Isolate Select > Remove Selected. To display only the UVs that have the current image assigned 1 Show the texture (in the UV Texture Editor, choose Image > Display Image). If more than one texture is associated with the mesh, select the texture you want to work on using the Textures menu.


When you are in component selection mode, the Textures menu lists shading groups assigned to the selected components. In object selection mode, the menu lists all shading groups assigned to the entire mesh. 2 To only show faces with the current image assigned, in the UV Texture Editor turn on View > View Faces of Selected Images. 3 To show all faces again, turn off View > View Faces of Selected Images. To display only the faces inside the selected UVs or edges 1 Select UVs or edges to define a border. 2 In the UV Texture Editor, turn on View > Contained Faces. 3 To show all faces again, turn off View > Contained Faces. To display only the faces that share the selected UVs or edges 1 Select UVs or edges. 2 In the UV Texture Editor, turn on View > Connected Faces. 3 To show all faces again, turn off View > Connected Faces.

Move, rotate, and scale UVs You can manually move, scale, or rotate UVs and UV shells in the UV Texture Editor. For example, you may wish to move individual UVs or entire UV shells to improve their layout, or scale UV shells to ensure they make optimal use of the 0 to +1 texture space. To...

Do this:

Move, rotate, or scale UV positions.

Use the appropriate tool. 1 Select the UVs you want to reposition. 2 Select the Move, Rotate, and Scale tools from the Toolbox. Note: Scaling UVs of multiple polygonal objects together in the UV Texture Editor

Move, rotate, and scale UVs | 35

To...

Do this: may produce unexpected results. Work on the UVs of one object at a time.

Move a UV shell and ensure that it does not overlap other shells.

Use the Move UV Shell Tool. 1 From the UV Texture Editor menu, select Tool > Move UV Shell Tool > . (Or click the Move UV Shell Tool icon on the toolbar of the UV Texture Editor. 2 Select the UV shell you want to move by either clicking the shell or dragging a bounding box around it in the UV Texture Editor. 3 Drag the manipulator to move the UV shell. Note: To prevent the repositioned shell from overlapping other shells, turn on the Prevent overlap option. See Tool > Move UV Shell Tool on page 150.

Rotate UVs by an exact number.

Use the Rotate UVs options. 1 Select the UVs you want to rotate. 2 Select Edit UVs > Rotate >

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3 Enter a number for the rotation angle and click Rotate or Apply.

Flip UVs to flip the texture placement on the mesh.


Use the Flip UVs options. 1 Select the faces you want to flip texture placement on.

To...

Do this: 2 Select Edit UVs > Flip >

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3 Select the Direction and Coordinate system on which to flip and click Apply and Close or Apply.

Scale UVs to fit within the 0 to +1 texture range.

Use the Normalize UVs options.

1 Select the faces whose UVs you want scaled within the 0 to 1 range in the UV Texture Editor. 2 Edit UVs > Normalize >

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3 Select the method which you wish to normalize with and click Apply and Close or Apply.

Move UVs to (0,0), (1,1), (1,0), or (0,1) in texture space.

Use the Unitize UVs options. 1 Select the faces whose UVs you want to have unitized. 2 Select Edit UVs > Unitize > . 3 Adjust the settings as desired and click Apply and Close or Apply.

Discrete Rotate and Scale

You can use Discrete rotate and Discrete scale to rotate or scale your UVs by fixed increments. You can modify these increments in the Step size field. This is useful to restrict the rotation or scale amount to a specific factor.


Discrete rotate or Discrete scale can be found in the Tool Settings Editor when the Rotate Tool or Scale Tool are selected respectively. To use Discrete rotate or Discrete scale 1 Select the UVs you want to rotate or scale in the UV Texture Editor. 2 Double-click either the Rotate Tool or Scale Tool from the Toolbox. The Tool Settings Editor appears. 3 Turn on Discrete rotate or Discrete scale. 4 Adjust the Step size. 5 Use the manipulators to rotate or scale your object. The object rotates or scales in set increments.

UV Snapping

You can use snapping in the UV Texture Editor to transform UVs with great precision the same way you can use it to transform components in the scene view.

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Snap to the grid, a curve, points, or a view plane

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The pivot point

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Rotate Tool

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Scale Tool

Example 1: Snapping to projections When Snap to Points is on, you can also snap to UV projections along the U or V axis. A UV projection is a straight line in either the U or V direction from a UV. This is useful if you don’t want to snap two UVs together, but want them to line up in the UV Texture Editor.


You can use this functionality on multiple UVs at once to obtain different results. With the Retain Component Spacing option off, all the selected UVs snap to the nearest UV projection. Notice below that the selected UVs line up with the circled UV beneath them when translated right.

With the Retain Component Spacing option on, the center of the selected UVs snaps to the nearest UV projection. The relative spacing of the selected UVs is maintained. Notice below that the shape of the selected UVs is maintained and only the center of the selection (the manipulator) lines up with the circled UV beneath them when translated right.

The behavior of snapping to UVs and UV projections depends on the UV Snap Tolerance setting in Window > Settings/Preferences > Preferences in the Snapping section under Settings.

Example 2: Pivot snapping You can use snapping in the UV Texture Editor to position pivots for rotation or scaling. This helps to reduce the number of steps in some workflows and ensures that transformations along existing points are accurate.


For example, if you want to rotate the upper portion of a cube’s UV shell 90 degrees around its bottom left corner, you can rotate it first, then translate it left.

However, it’s easier and more precise to move the pivot point to the bottom left corner and rotate on that pivot.

To rotate around a UV 1 Select the UVs you want to rotate. 2 Select the Rotate Tool from the Toolbox. 3 Press Insert or Home. The manipulator changes to the move pivot manipulator.


4 Hold v on your keyboard or select the Snap to Points option in the status line. 5 Move the pivot to the UV you want to rotate around. When you move the manipulator close to a UV, the pivot automatically snaps to it. You can then move the pivot from UV to UV. 6 Press Insert or Home to return to the rotate manipulator 7 Rotate the UVs. You can use a similar workflow to scale a set of UVs relative to a specific point.

Dolly or track within the UV Texture Editor To...

Do this

Change the view of the UVs.

Use the camera move keys: ■

alt + the middle mouse button to track

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alt + the right mouse button to dolly in and out

Zoom in/out to show all UVs.

In the UV Texture Editor, choose View > Frame All.

Zoom in/out to show the selected UVs.

In the UV Texture Editor, choose View > Frame Selection.

Make texture borders look thicker.

In the UV Texture Editor, click the Toggle Texture Borders button.

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Separate and attach UV shells on page 52

Dolly or track within the UV Texture Editor | 41

Display a texture behind the UVs You can display the image associated with a texture in the UV Texture Editor. The image appears behind the UVs so you can rearrange the UVs in relation to the image. To...

Do this

Display the texture image behind the UVs.

In the UV Texture Editor, click the Toggle Image button on the toolbar or select Image > Display Image.

Set the image ratio.

In the UV Texture Editor, click the Toggle Image Ratio button on the toolbar or select Image > Use Image Ratio.

Switch between blended and sharp-edged pixels.

In the UV Texture Editor, click the Toggle Filtered Pixels button on the toolbar or select Image > Display Unfiltered.


To...

Do this

Switch between showing a mesh texture and a per-face texture.

Select the mesh object to show a mesh texture, or faces to show per-face textures.

Choose a texture to display (if more than one texture is applied to the mesh).

In the UV Texture Editor, select the texture you want to work on from the Textures menu. When you are in component selection mode, the Textures menu lists shading groups assigned to the selected components. In object selection mode, the sub-menu lists all shading groups assigned to the entire mesh.

Crop the image within UV coordinates.

In the UV Texture Editor, choose Image > Image Range >

.

If the texture quality is poor or if parts of the texture do not display correctly, you can modify the display quality with the Hardware Texturing settings in the Attribute Editor for the material node. If you are using a file texture, the best display mode for the Texture resolution setting is Default. (The other settings, such as High, are best for procedural textures.) If you experience resolution or cropping problems in the texture image display, use Image > UV Texture Editor Baking to bake the texture. You must rebake the texture (using UV Texture Editor toolbar on page 154) after making changes to the texture (File node and place2dTexture node attributes) in order to see the effect of those changes.

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Delete UVs Delete UVs removes UV texture coordinates from the selected face(s). When you select a face on the mesh that has an assigned texture and delete the UVs,

Delete UVs | 43

the assigned texture doesn’t appear any longer on the face(s) where the UVs were deleted. You can re-create the UVs for the selected faces (or the entire mesh) using the UV projection mapping operations. Deleting UVs removes only the UV texture coordinate data on the mesh and does not affect the vertices on the mesh. To delete UV texture coordinates for a selected face 1 In the scene view, select the face(s) for which you want to delete the UVs.

2 Select Edit UVs > Delete UVs. (If you are working in the UV Texture Editor you can select Polygons > Delete UVs.) The UVs associated with the selected face(s) are deleted.

Because the selected faces have no UVs, textures cannot be applied to them until UVs are re-created. NOTE When you select one UV in the UV Texture Editor and select Polygons > Delete UVs, all of the UVs for the face(s) associated with the UV you selected also get deleted. For this reason, the Delete key on the keyboard does not delete UVs because of the unique requirements of this operation.

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Edit UVs > Delete UVs on page 137

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Update a texture image after UV modification Warp Image modifies a texture image by comparing two UV sets on a single polygonal mesh and produces a new bitmap image. To use this feature you must specify a source image, as well as a source and destination UV set for the model from which the UVs will be referenced for the image manipulation. Warp Image produces a new target image as the result. You choose Warp Image by selecting Edit UVs > Warp Image from within the Polygons menu set or from the Polygons menu in the UV Texture Editor. Warp Image is useful in the following situations: ■

When you don’t want to manually regenerate an image for an existing texture map when the UVs for the texture have been changed. Warp Image will calculate where the pixels should be relocated and update the texture for you. This is helpful when the UVs on a polygonal mesh have been refined in some way. For example, if it were necessary to cut, merge, or optimize the UVs for some reason, the way an associated texture map was displayed on the polygon object would be affected as a result.

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Creating more texture space for key areas in a texture map. For example, when texture mapping a face, the UVs surrounding the eyes and mouth can be scaled larger so there are more pixels assigned to these areas in the final texture map. If you scaled the UVs within the UV Texture Editor to optimize the texture space, you can warp the associated image to account for the modified UVs. NOTE Warp Image may not produce as high quality an image as you expect. It may be necessary to perform additional post processing work on the image.

Warp Image requires two UV sets in order to produce a new image (in addition to the original image). Unless you have previously created a UV set for the polygonal mesh it is highly recommended that prior to doing any UV editing within the UV Texture Editor, you explicitly save a copy of the original UVs for the textured polygonal mesh as a UV set by selecting Polygons > Copy UVs to UV Set > Copy into New UV Set. In that way you’ll have the original UV set to revert back to should you require it.

Update a texture image after UV modification | 45

Prior to warping an image, two UV sets must exist for the polygonal mesh: the existing UV set from which the original texture is assigned, and a second UV set that will be referenced for modifying or warping the image. The two UV sets will be referenced as the Source and Destination UV sets. To warp an image based on updated UVs 1 Do one of the following: ■

From the Polygons menu set, select Edit UVs > Warp Image >

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In the UV Texture Editor, select Polygons > Warp Image >

. .

The Warp Image Options window appears. 2 Type the file name for the source image you want to warp in the Source Image Name field or browse to the location and select the file name. 3 Type the file name for the new image you want created by Warp Image in the New Image Name field or browse to select a location and image name. 4 Type the names of the Source and Destination UV sets that you want the Warp Image feature to reference. If you forget the names of the UV sets, they can be viewed in the UV Texture Editor by selecting the UV Sets menu and viewing the UV set names in the drop-down list. 5 Set any remaining options that you want and then click Warp Image. 6 Warp Image calculates the new pixel positions for the new image and outputs the image to the location you specified. To view the new texture on your surface mesh you must edit the currently assigned shader to use the new image. Ensure that you have the correct UV set applied to the mesh so you see the results you expect.

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Edit UVs > Warp Image on page 115


Use the UV Texture Editor grid The UV Texture Editor has a grid feature that lets you accurately control the position and spacing of UVs when you move, rotate, or scale them. To...

Do this

Show or hide the grid.

In the UV Texture Editor, click the Toggle Grid button on the toolbar or choose View > Grid.

Change the grid.

In the UV Texture Editor, right click the Toggle Grid button on the toolbar or choose View > Grid >

.

Snap UVs to the grid.

Use grid snapping (hold x).

Change how UVs snap.

Double-click the Move tool to open its options panel. Use the Retain Component Spacing option to control how UVs snap: When off, all selected UVs will snap to the same point. When on, selected UVs will keep their positions relative to each other as they move.

Snap UVs to pixels.

In the UV Texture Editor, click the Toggle Snap to Pixel button in the toolbar, or choose Image > Pixel Snap.

Use the UV Texture Editor grid | 47

To...

Do this To control whether snapping is to pixel corners or centers, display the Move Tool options, (make sure focus is on the UV Texture Editor) and set Placement to Snap Corner or Snap Center.

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Save an image of the UV layout After you create a final layout of your UVs in the UV Texture Editor, you can export an image of the UV shells using UV Snapshot. UV Snapshot saves a bitmap image of the UV Texture Editor’s 2D view at a user defined resolution. You can use the image in the Maya® Paint EffectsTM canvas or image editing application such as Adobe® Photoshop®, and paint a texture to match the UVs. UV Snapshot works with multiple selected objects and has the ability to extend the region of the snapshot area to encompass the entire range of the selected UV texture coordinates, regardless of whether the UVs belong to a polygonal or subdivision surface type. UV Range options let you specify the region of the UV Texture Editor’s view you want to have captured for the output image. UV Snapshot is also available from the Subdivs menu in the UV Texture Editor to facilitate an easier workflow when working with subdivision surfaces. To save an image using UV Snapshot 1 In the scene view, select the mesh or components so their UVs appear in the UV Texture Editor. 2 In the UV Texture Editor, choose Polygons > UV Snapshot. (You can also select UV Snapshot from the Subdivs menu in the UV Texture Editor) 3 Enter a name in the File name field that you want to export to.


4 Set the size of the image using the Size X and Size Y fields. 5 Choose a Color value for the UV edges. Unless specified, the background color for the image will be black. 6 Choose an Image format. 7 Set the UV Range Options. 8 Click OK.

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UV Texture Editor reference on page 139

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UV Texture Editor menu bar on page 140

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UV Texture Editor toolbar on page 154

Modify UVs using the UV Lattice Tool You can modify the layout of multiple UVs at once on polygonal or subdivision surface geometry using the UV Lattice Tool in the UV Texture Editor. The UV Lattice Tool gives you a high level of control over your UVs by letting you edit the layout of numerous UVs at a time with a 2D lattice deformer. To edit the layout of your UVs using the lattice manipulator 1 In the scene view, select the polygonal or subdivision surface object whose UVs you want to manipulate. 2 Select Edit UVs > UV Texture Editor. The UV Texture Editor appears. 3 In the UV Texture Editor’s view, switch to UV mode. Right-click in the view and select UV from the marking menu that appears. 4 In the UV Texture Editor menu bar, select Tool > UV Lattice Tool >

.

The UV Lattice Tool Options window appears. 5 Set the UV Lattice Tool options and then click Apply and Close.

Modify UVs using the UV Lattice Tool | 49

6 Select Tool > UV Lattice Tool or click the UV Lattice Tool in the UV Texture Editor toolbar.

button

7 In the UV Texture Editor view, drag around the UVs you want to manipulate. This selects the target UVs for the lattice. A UV lattice manipulator appears over and surrounding the target UVs. 8 Select the lattice edges or control points that affect the region of UVs you want to manipulate by clicking them. Shift-click lattice edges or control points to include them or remove them from your selection.

9 Drag the selected lattice edges or control points to deform the layout of the target UVs.

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Modify UVs using the UV Smudge Tool You can drag or smudge the layout of UVs on your polygonal or subdivision surface geometry using the UV Smudge Tool in the UV Texture Editor. The Smudge Tool gives you a high level of control over your UVs, providing a more free-form approach to manipulating the layout of your UVs. To smudge the layout of your UVs 1 Select the geometry whose UVs you want to manipulate. 2 Select Edit UVs > UV Texture Editor. The UV Texture Editor appears. 3 In the UV Texture Editor menu bar, select Tool > UV Smudge Tool > . The UV Smudge Tool Options window appears. 4 Set the UV Smudge Tool options as required and then click Apply and Close.

5 Select Tool > UV Smudge Tool or click the UV Smudge Tool in the UV Texture Editor toolbar. The following occurs:

button

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The UV Texture Editor’s view switches to UV mode.

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All the UVs of the current geometry become selected.

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The UV Smudge Tool brush appears in the UV Texture Editor’s view.

6 If the Middle Mouse Initiates tool setting is off, do one of the following: ■

In the UV Texture Editor’s view, drag to smudge the layout of all your UVs.

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In the UV Texture Editor’s view, Shift-drag around the UVs you want to select and then drag to smudge the layout of the selected UVs.

Modify UVs using the UV Smudge Tool | 51

If the Middle Mouse Initiates tool setting is on, do one of the following: ■

In the UV Texture Editor’s view, middle-drag to smudge the layout of all your UVs.

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In the UV Texture Editor’s view, drag around the UVs you want to select and then middle-drag to smudge the layout of the selected UVs.

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Separate and attach UV shells Maya provides several features for separating, merging, and attaching UVs. These features can be particularly useful when working with UVs that were generated using the Automatic Mapping feature. To...

Do this

Separate a UV shell along the selected edges.

Select Edit UVs > Cut UV Edges.

Attach UV shells along the selected edges.

Select Edit UVs > Sew UV Edges.


To...

Do this

Attach UV shells along the selected edges and move the shells together.

Select Edit UVs > Move and Sew UV Edges

Merge the selected UVs.

Select Edit UVs > Merge UVs. Merge UVs only merges the UVs that share the same vertex. You can specify an option for the maximum distance Maya will move UVs to merge them.

Automatically attach and move small shells.

Select all the shells and choose Edit UVs >

> . Turn off Limit Shell Size and click Apply.

. Move and Sew UV Edges > Turn on Limit Shell Size and set the maximum size (in number of faces) for UV shells. Shells larger than this number will not move. Click Apply.

After performing a Move and Sew UV Edges operation, you can select the node (polyMapSewMove) and edit it in the Attribute Editor or Channel Box to adjust the Number Faces.

Separate and attach UV shells | 53

Notes ■

A single edge cannot be cut unless it touches a border.

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Use the Select > Select Shell in the UV Texture Editor to select a UV piece after cutting.

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Display overlapping UVs on page 54

Display overlapping UVs The Shade UVs feature lets you see whether any UVs or UV shells overlap when viewed in the UV Texture Editor. You can also see the UV winding order on the selected UV shells. For more information on UV winding order see Display UV winding order on page 55. When Shade UVs is turned on any selected UV shells appear shaded in a semitransparent way. Areas where shading appears more opaque indicate the regions of overlap. Overlapping UVs are often undesirable because any associated texture maps will also overlap on the related surface meshes.


To display overlapping UVs in the UV Texture Editor 1 In the UV Texture Editor, select any UVs or UV shells whose display you want to appear as shaded. 2 Do one of the following: ■

In the UV Texture Editor menu, select Image > Shade UVs >

.

The UV Map Shading Options window appears to let you modify the default settings for color and opacity. For more information see Image > Shade UVs on page 151.

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Click the Shade UVs icon ( Texture Editor.

)located on the toolbar of the UV

The selected UV shells update to a semitransparent shaded display. Areas where the UVs or UV shells overlap are visually apparent by the increased opacity of the shading in the overlapping regions. TIP You can correct overlapping UVs and UV shells using the Unfold and the Layout features. For more information see Layout UV shells on page 58. You can also view the texture borders for a UV shell by selecting Display > Polygons > Texture Border Edges.

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Unfold a UV mesh on page 65

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Layout UV shells on page 58

Display UV winding order You can visually determine the winding order on UV shells when you work in the UV Texture Editor using the Shade UVs feature.

Display UV winding order | 55

When the Shade UVs feature is turned on, selected UV shells whose UV winding order is clockwise will appear shaded with a semi-transparent blue color. UV shells whose UV winding order is counterclockwise will appear shaded with a semi-transparent red color. The UV winding order refers to the direction in which UV texture coordinates are stored on the surface mesh for a particular face. This direction can be either clockwise or counter-clockwise and is important to know when texture mapping polygon meshes because it can affect whether a texture maps correctly or not.

Texture maps can appear flipped or reversed on a polygon mesh depending on how the UV shell is wound. The UV winding order can be reversed for the following reasons: ■

The original UV mapping used to create UV texture coordinates may have produced an incorrect UV winding order. For example, if you map a cube using planar UVs, the UV winding will be clockwise on the UV shell closest to the projection plane and counterclockwise on the UV shell on the face on the opposite side of the cube.

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When the normals are flipped on a face of a polygon mesh, the UV winding order on the face is reversed.


To display the winding order on UVs in the UV Texture Editor 1 In the UV Texture Editor, select any UVs or UV shells whose winding order you want to determine. 2 Do one of the following: ■

In the UV Texture Editor menu, select Image > Shade UVs.

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Click the Shade UVs icon located on the toolbar of the UV Texture Editor.

The selected UV shells appear shaded and semitransparent. Shells with a clockwise winding order (front facing) appear shaded in blue. Shells with a counter-clockwise winding order (back facing) appear shaded in red. Areas where the UV shells overlap are visually apparent by the increased opacity of the shading in the overlapping regions. 3 Any UV shells that display with incorrect UV winding can be modified using the Flip UVs feature. For more information see Flip or rotate UV shells on page 79. NOTE You can modify the default settings for color and opacity for the Shade UVs feature by selecting Image > Shade UVs > Image > Shade UVs on page 151.

. For more information see

Display UV winding order | 57

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Image > Shade UVs on page 151

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Tangent Space

Layout UV shells The Layout feature automatically repositions UV shells so they don’t overlap in UV texture space and maximizes the spacing and fit between them. This is useful for ensuring that the UV shells occupy their own separate UV texture space. For example, if you are applying Fur to a surface, the UV texture coordinates on a given shell must not overlap. In general, you should keep UV shells separated for convenience and clarity. It is not absolutely necessary to keep UV shells separate. For example, you may want the UV shells to overlap so different faces use the same region of a texture.

You can also use the Layout feature to: ■

Scale or stretch the UV shells to fit within the 0 to 1 coordinates of the UV Texture Editor. This is useful if you need to maximize the texture space used when creating a texture map. For example, when using 3D Paint.

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Flip UV shells that correspond to opposite sides of a model. This automatically corrects the orientation of the UV shell if the UV winding order is incorrect. See Display UV winding order on page 55.


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Arrange the UV layout of multiple selected objects simultaneously. This improves your efficiency when you need to quickly sort the UVs for multiple objects within the UV Texture Editor, or when multiple objects need to share different parts of the same texture. By default, when Layout is used with multiple objects, the UVs for each object are placed individually. As a result, they overlap each other within the UV Texture Editor. This saves you the work of having to lay out each UV set individually. When the Layout Multiple Objects option is set to Non-Overlapping, the UVs are laid out as if all of the objects were combined as one. The Layout feature is also available from within the UV Texture Editor by selecting Polygons > Layout from the UV Texture Editor’s menu bar. NOTE Before using Layout you should already have performed the necessary UV projection mapping or Automatic Mapping. That is, the Layout feature will only arrange existing UV texture coordinates, it will not create them.

To lay out UVs for multiple objects simultaneously 1 Select the objects or faces whose UVs you want to lay out. 2 Select Edit UVs > UV Texture Editor to display the UV Texture Editor. 3 In the UV Texture Editor, select Edit UVs > Layout>

.

The Polygon Layout Options window appears. 4 In the Layout UVs Options window set the following options depending on your required outcomes: ■

Set Layout objects to Per Object (overlapping) (default) when you require multiple object’s UVs to overlap within the UV texture space.

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Set Layout objects to Single or Multiple Objects (non-overlapping) when you require the UVs to be separated. This is useful when you need each UV set to be separate and distinct from each other.

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Set Prescale to Object to maximize the spacing and fit between the UV shells.

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Set the Shell Stacking option to adjust the spacing between UV shells by specifying how the bounding shape for the UV shells will be described. In general, the UV layout will have more space when the Bounding Box option is set, and less space when the Shape option is

Layout UV shells | 59

set. When the Scale Mode is set to Uniform the shells are scaled to make optimal use of the UV texture space. 5 Click Apply to perform the layout operation or Layout UVs if you want to perform the operation and close the Layout UVs Options window.

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Edit UVs > Layout on page 129

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Map border UVs to a square or circle Prior to relaxing any interior UVs on a shell you should attempt to untangle the border UVs on the exterior of the UV shell. You can do this using the Map UV Border feature and with the Straighten UV Border feature. When you use Map UV Border you can move the UVs on the border of a UV shell out to the edges of the 0 to 1 texture space range (square), or in a circle inscribed within the 0 to 1 range. Mapping UVs so they use the entire 0 to 1 texture range is useful when you need to maximize the texture space required for a texture map. You can optionally scale the edges proportionally as you move the border UVs. This is useful for untangling borders before you use Relax UVs to untangle interior UVs.


To map border UVs to a square or circle 1 Select one UV on the shell whose border UVs you wish to map. The UV you select will represent the lower left corner of the square or circle border map you wish to make. The UV you select is important as it will determine where the UV shell will be mapped to the 0,0 origin of the UV texture space. If the resulting UV border mapping appears skewed, you may wish to undo it, and select another UV and map again. 2 Select Edit UVs > Map UV Border >

.

Map border UVs to a square or circle | 61

If you are using the UV Texture Editor, you can select Polygons > Map UV Border >

.

3 Set the options, then click Map or Apply. The border UVs are mapped based on the settings you made. The interior UVs will remain unchanged. You can untangle the interior UVs using the Relax UVs feature. 4 If the UV mapping appears correct, you can use the Relax UVs feature to untangle the interior UVs on the shell.

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Edit UVs > Layout on page 129

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Straighten border UVs on page 62

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Relax and untangle UVs on page 63

Straighten border UVs Straighten UV Border is useful when you want to untangle the border of a UV shell, such when the border edge loops around itself. Straighten UV Border provides more control than the Map UV Border operation.

To straighten border UVs 1 In the UV Texture Editor right-click and select UV from the marking menu. 2 Select the UVs around the tangled UV border.


It doesn’t matter if you select interior UVs along with border UVs. Straighten UV Border only acts on the borders. In some cases, it is difficult to select the UVs you want to straighten without selecting other UVs you want to leave unaffected. In these cases, you can leave a gap in your selection and use the Fill Gaps in Selection option to straighten the UVs you could not select. 3 Select Edit UVs > Straighten UV Border. If you are using the UV Texture Editor, you can select Polygons > Straighten UV Border >

.

4 Select the polyStraightenUVBorder node and edit the attributes in the Attribute Editor or Channel Box.

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Edit UVs > Straighten UV Border on page 120

Relax and untangle UVs

Relax a UVs to untangle and even out the spacing between UV coordinates on a shell. Relax is useful for untangling interior UVs in combination with the Map UV Border feature. You can begin by mapping the UVs to a border (either a square or a circle) then relax the UVs to even out the spacing of the UVs. You can relax UVs using the Smooth UV Tool or the Relax feature, each with their own applications. The Smooth UV Tool allows you to view the affected UVs as you relax them. This is useful for making precise visual adjustments. You can also use this tool to relax either the entire UV shell or only a subset of UVs on it. While both the Smooth UV Tool and the Relax feature allow you to pin the borders of your UV shell so they don’t move, the Relax feature has additional options that let you pin selected or unselected UVs while relaxing all the others. The Relax feature always applies to the entire shell.

Relax and untangle UVs | 63

To relax UVs on a shell 1 From the UV Texture Editor, select a set of UVs.

2 Select Tool > Smooth UV Tool or select toolbar.

from the UV Texture Editor

Two small controls appear at the bottom-left of the selected UVs.

3 Click the box labelled Relax and drag the mouse right. The further you drag, the more the selected UVs relax.

NOTE You can move the Unfold and Relax controls by dragging the yellow target icon at the top left of the controls. With the Smooth UV tool you can choose to relax the entire mesh or only part of it. However, you cannot use it to relax multiple UV shells at once. Additionally, there may be instances when you need more control over some aspects of the relax process. For example, when relaxing UVs you may want to pin specific UVs. You can do this with the Relax option. To relax UVs using the Relax feature 1 Select one UV on the shell whose UVs you want to untangle (relax). 2 Select Edit UVs > Relax >

.

If you are using the UV Texture Editor, select Polygons > Relax >


.

3 Select the options, then click Relax or Apply. You can apply Relax multiple times to move the UVs more.

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Map border UVs to a square or circle on page 60

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Edit UVs > Relax on page 121

Unfold a UV mesh

The Unfold feature lets you unwrap the UV mesh for a polygonal object while attempting to ensure that the UVs do not overlap. Unfold helps to minimize the distortion of texture maps on organic polygon meshes by optimizing the position of the UV coordinates so they more closely reflect the original polygon mesh. For example, if the initial shape of the UVs cause a patterned texture to distort, you can use the Unfold feature to minimize the distortion because it attempts to maintain the UV’s relationship relative to the original polygon mesh. You can access Unfold by: ■

selecting the Smooth UV Tool (Tool > Smooth UV Tool in the UV Texture Editor).

Unfold a UV mesh | 65

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selecting Edit UVs > Unfold from within the Polygons menu set or from within the UV Texture Editor by selecting Polygons > Unfold

Unfold works well in situations where UV meshes need to be created from polygonal models that have complex organic shapes. In these situations, other projection methods may not be as successful and automatic mapping would produce too many individual UV shells that would necessitate many move and sew operations afterwards. For example, polygon models that are prone to overlap via other projection methods would be well suited for the Unfold feature. When compared to Automatic Mapping, Unfold produces good UVs on larger UV shell areas because it keeps neighboring faces together (by contrast, Automatic Mapping produces many separate UV shells). Unfold is not needed when working with simple, non-organic poly mesh forms. In these cases, other projection techniques or automatic mapping would be better suited and more straightforward. For example, a wall can be planar-projected or a bottle can be cylindrically projected.

Unfold setup Prior to using the Unfold feature you should consider the following: ■

The polygon mesh must have UV texture coordinates. The mesh must first have UVs to unfold. You can create UVs using almost any mapping technique (for example, cylindrical mapping, spherical mapping, and so on). In general, the initial shape of the UVs doesn’t affect the final unfolded result. However, their initial shape should be as distortion free as possible to avoid long computations when unfolding and to facilitate UV edge selection for cuts.

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The UV mesh must be cut in a manner that allows the Unfold feature to freely unwrap the UV mesh.


When unfolded, the polygon mesh should be able to lay relatively flat without overlapping. Imagine cutting a shirt along its sides so that its pattern lies flat over a table. Like this example, in Maya you must cut edges from the original shell to unfold a UV texture.


Locating the edge cuts requires some planning, in advance of the actual cuts, to obtain the best unfolded result. The better the edge cuts, the better the correlation between the original polygons and their corresponding UV mesh. In addition, you should anticipate that the polygon edge cuts will result in texture mismatches along edges, and locate edges on the model where they are least visible. For example, make edge cuts under the arms or on the back of the legs of a character. ■

Consider the UVs you want to pin. When unfolding a UV shell, it is important to consider where you are unfolding relative to. A pinned UV provides an anchor around which other UVs can be unfolded. Often, if you do not pin at least one point when unfolding a UV shell, the shell will unfold into a very tiny mesh or into an undesirable shape. For symmetrical meshes, you often want to pin a UV along the line of symmetry. For more information about pinning, see Pinning on page 71. When using the Smooth UV Tool, any unselected UVs are automatically pinned. Conversely, when using the Unfold command, you can choose to pin any selected UVs or unselected UVs.

To prepare a UV shell for unfolding 1 Ensure the polygon model you are working with has UVs. To do this, perform an initial UV mapping operation on the mesh to produce a UV texture mesh (for example, using Create UVs > Cylindrical Mapping). NOTE The shape of the UV texture mesh is not critical at this stage because the Unfold feature will modify it. 2 In the scene view, determine the locations where you will perform edge cuts on the UV texture mesh using the 3D polygonal model as a reference. Dollying and tumbling the scene view helps you with this task. For additional tips on determining edge cuts, see UV unfolding workflow tips on page 70. TIP When editing UVs you can use the perspective view and the UV Texture Editor, side by side, to locate and select or deselect the polygon vertices, edges, and UVs. To do this, right-click on any layout shortcut in the Toolbox and select Persp/UV Texture Editor from the drop-down list. 3 In the scene view you can select vertex edges that lie in a contiguous line by double-clicking one of the edges on the line. You can also select a path


of edges between two points using the Select > Select Shortest Edge Path Tool. 4 Using both the 3D view and UV Texture Editor as required, continue to select and cut the edges of the UV mesh in the locations you predetermined earlier using Polygons > Cut UV Edges in the UV Texture Editor. 5 Find and make note of the UVs you want to pin. Once you are satisfied with the cuts you’ve made, you are ready to unfold the UV shell. To unfold a set of UVs 1 From the UV Texture Editor, select a set of UVs. Any UVs you leave unselected will be pinned when you unfold the mesh.

2 Select Tool > Smooth UV Tool or select toolbar.

from the UV Texture Editor

Two small controls appear at the bottom-left of the selected UVs. 3 Click the box labelled Unfold and drag the mouse right. The further you drag, the more the selected UVs unfold.

NOTE You can move the Unfold and Relax controls by dragging the yellow target icon at the top left of the controls. With the Smooth UV tool you can choose to unfold the entire mesh or only part of it. However, you cannot use it to unfold multiple UV shells at once.


You may also want to control specific aspects of the Unfold operation. You can do this with the Unfold option. To unfold a polygon UV texture mesh using the Unfold feature 1 In the UV Texture Editor, select the polygon UV mesh, and then selecting Polygons > Unfold >

.

2 Select the options you want and then click Apply and Close. 3 When you want to stop the Unfold operation, press Esc. In general, the Unfold operation requires several iterations to achieve the desired final result. It may often be necessary to refine your cuts, add new ones, move and sew UV edges, or add/change pinned UVs between iterations. When you are satisfied with your final unfolded result, use Polygons > Layout as a final step to ensure the UVs are laid out as you require. The following workflow tips can be useful in helping you achieve your desired final unfolded result.

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Edit UVs > Unfold on page 123

UV unfolding workflow tips Single vs. multiple meshes While it is possible to unfold a complete UV mesh for one model in one piece, an alternate approach might be to cut the UV mesh into smaller sections and unfold portions of the mesh separately. With this strategy you can more easily control regions of the unfold by pinning and so on. You’ll need to determine where you can safely cut the mesh, and later re-sew the UVs if required after the unfold operations are complete. Which approach you take will be determined by the complexity of the mesh and your individual production requirements.


Determining and selecting edge cut locations The edge cuts should be located on the UV mesh in such a way that the UV mesh would lay flat if it were unfolded. Edge cuts are important because they allow the UV texture coordinates to freely unfold with as little distortion as possible during the Unfold operation. The edge cuts should also be located in areas of the UV mesh where they will stay mostly unseen in the final rendered images. This reduces the possibility of the viewer seeing the texturing artifacts that can result along texture edges. You can quickly select a path of edges using the Select Shortest Edge Path Tool (Select > Select Shortest Edge Path Tool). The Edge Loop tools can be useful for quickly inserting edges into the mesh in locations that are not obvious to the viewer.

Quick Select sets Whenever you need to make complex edge, vertex, or UV selections repeatedly, you can create selection sets for these components (called Quick Select sets) to easily select these components later on. To create Quick Select sets, select the components you want in the set and then select Create > Sets > Quick Select Set. This can be particularly useful when you need to repeatedly select UVs for pinning during the unfold operations.

Highlighting texture borders It is critical to view and select border edges in both the scene view and the UV Texture Editor. Turn on the display of texture borders by selecting Display > Polygons > Texture Border Edges. This displays the UV borders on the polygon mesh as thicker lines so you can see your progress as you cut the UV edges.

Pinning Depending on where you initially cut the edges of the UV texture mesh, you can pin specific locations or regions of the UV texture mesh to create temporary anchor points to use with the Unfold feature. For example, with a polygon mesh of a quadruped, you can select the vertices along its spine beginning at the tip of the nose and ending at the tip of its tail (assuming this has not been cut), then align these vertices to a vertical axis or horizontal axis within the UV Texture Editor. When you perform the next Unfold iteration, turn on the Pin Selected UVs option in the Unfold UVs Options window so the selected UVs remain anchored while the Unfold operation proceeds. The UVs will then


unfold in relation to the area you pinned. If you create QuickSets of the UV components involved, your pinning operations will proceed more quickly. Pinning is useful for ensuring areas don’t move during the unfold. It’s also useful when you have some regions unfolded to your satisfaction, and need to maintain those regions while performing additional unfold iterations. When necessary you can pin a shell’s border edges. In this way you can use the Unfold feature while the shell border is pinned to unfold the shells’ interior UVs. In general, you get better results when pinning extreme points on the mesh and respecting the polygon object’s symmetry whenever possible. When using the Smooth UV tool to unfold, any unselected UVs are automatically pinned.

Constraining the unfold to either a horizontal or vertical direction By default, the Unfold feature unfolds the UVs in all directions in an unrestricted manner. You can constrain the unfold process so the UVs are constrained to unfold in either the vertical or horizontal direction as they appear in the 2D view of the UV Texture Editor. This can be useful when the appearance of the UVs is fine in one direction, but needs refinement in another. When using the Smooth UV Tool, you can constrain the direction of the unfold operation by holding the Shift button while dragging the mouse. When using the Unfold option, you can set the Unfold constraint to either Vertical or Horizontal to constrain the direction of the unfold. The Unfold constraint setting also respects any pinning settings you may have set for the unfold operation.

Aligning UVs Use Edit UVs > Align to snap UVs to match any vertical or horizontal lines that would naturally occur on the texture. Aligning UV edges that run down the axis of symmetry can be used to your advantage. For example, the line of UVs that run down the spine of a symmetrical four-legged animal. You can select and align these UVs and then pin them so they act as a benchmark for further unfold operations.


UV Lattice Tool The UV Lattice Tool in the UV Texture Editor can be used to modify a region of a UV shell before performing further Unfold operations.

Example: Lay out a UV shell using unfold and relax

You can use the Smooth UV Tool to relax or unfold an entire UV shell into the UV space. You can then use the same tool to fix small imperfections in the shell. The following workflow provides the following benefits: ■

It is easier to assign a texture to a square area.

■

Ensures the texture is spread evenly.

To map a shell to the UV space 1 Create a mapping for your object by selecting Create UVs > Planar Mapping from the Polygons menu set. In this case, a planar projection from the front (the Z Axis) is appropriate. In other cases you must determine the best projection to start with. 2 Open the UV Texture Editor (Window > UV Texture Editor).

Example: Lay out a UV shell using unfold and relax | 73

3 In the perspective view, select a path of edges along the back of the head starting at the top of the forehead and ending at the bottom of the neck. 4 In the UV Texture Editor, select Polygons > Cut UV Edges.

5 Select the central UV at the top of the forehead and in the UV Texture Editor, select Polygons > Unfold >

.

The Unfold Options window appears. 6 Turn on Pin UVs and Pin selected UVs. 7 Set the Unfold constraint to Horizontal. 8 Click Apply and Close. The UV shell unfolds relative to the selected UV on the forehead so that the previously cut edges are spread out horizontally.


NOTE Rather than using the Unfold option, you can also use the Smooth UV Tool to unfold the entire UV shell. In this case, you would select all the UVs except for the one at the top of the forehead and then Shift + drag the Unfold icon to the right. 9 Use the Scale Tool to scale the UV shell into the 0,1 texture space.

10 Select the edges on one side of the mesh. 11 Select Polygons > Straighten UV Border. The UV border straightens. 12 Repeat steps 10 and 11 for each side of the UV shell.


13 Turn on the Snap to grids option. 14 Select the Move Tool and move the border UVs to the edge of the 0,1 texture space. The Snap to grids option ensures that the UVs snap to the border precisely.


15 Select all the UVs. 16 Select Tool > Smooth UV Tool >

.

The Smooth UV Options window appears. 17 Turn on Pin Borders. This ensures that the UV border aren’t distorted. 18 Set Space to UV Space. 19 Click Apply and Close. Two controls named Unfold and Relax appear. 20 Drag the Relax control to the right. The entire UV shell, except for the borders, relaxes evenly.

With the Smooth UV Tool you can use your eye to judge how much the UV shell should relax. However, whether you use this method or the Relax option (Polygons > Relax), it is unlikely that the UV shell will be perfect.

, you can see small imperfections If you turn on the Shaded UV Display in your relaxed shell. For example, the UV shell around the eyes and corners of the mouth for this model cause the shell to overlap itself.


You can use the Smooth UV Tool to smooth out these problem areas. To smooth imperfections in a relaxed shell 1 Select Tool > Smooth UV Tool >

.

The Smooth UV Options window appears. 2 Turn off Pin Borders and then select Apply and Close. 3 Select a set of UVs around the eye. 4 Drag the Unfold control to the right until the UV shell no longer overlaps itself.

5 Repeat for the mouth.


6 You can select smaller or larger sets of UVs and use the Smooth UV Tool in conjunction with the transformation tools to quickly clean up your UV shell.

Flip or rotate UV shells The Flip and Rotate features let you easily change the orientation of UV shells within the UV Texture Editor. Flipping a UV shell is useful if you need to correct a UV shell that is reversed or reverse wound (see Display UV winding order on page 55).

Flip or rotate UV shells | 79

To flip UVs on a texture shell 1 Select the faces you want to flip the texture on. 2 Select Edit UVs > Flip. In the UV Texture Editor, you can select Polygons > Flip. or Select Edit UVs > Rotate. 3 Choose the direction to flip, and whether to flip within the bounding box of the selection (local) or across the texture space axes (global). 4 Click Apply.

Related topics ■

Edit UVs > Flip on page 111

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Edit UVs > Rotate on page 113

Copy UVs and color attributes between polygons You can copy UV, shader, and color per vertex attributes between faces of different polygon meshes using the Mesh > Clipboard Actions features. The ability to copy UV attributes between meshes is useful when a polygon mesh has been modified and you cannot further modify the UVs. It is also useful for copying attributes between meshes that have differing topologies. You can only copy attributes between polygon faces that have similar vertex counts. The copied UV attributes are placed in a separate shell. To copy UVs, shaders, or color per vertex data between polygons 1 Select the polygon face whose attributes you want to copy and choose Mesh > Clipboard Actions > Copy Attributes >

.

2 In the Copy Clipboard Options window, set the attributes you want to copy (UV, Shader, and Color) and click Apply and Close. NOTE You can set the options so that one or more attributes get copied to the clipboard.


3 Select the polygon face you want to copy the attributes to and choose Mesh > Clipboard Actions > Paste Attributes. The previously copied attributes are pasted onto the selected face. NOTE You can also clear the attributes contained on the clipboard by choosing Mesh > Clipboard Actions > Clear Clipboard.

Related Topics ■

Make a hole in a polygon face

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Mesh > Clipboard Actions > Copy Attributes

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Mesh > Clipboard Actions > Paste Attributes

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Mesh > Clipboard Actions > Clear Clipboard

Copy UVs and color attributes between polygons | 81

82

UV sets

4

Create UV sets The quickest way to create UV sets is while you map UVs. When you map UVs, open the options window, turn on Create New UV Set, and type a name in the UV Set Name box. For example, if you create two planar mappings, one from the top and one from the side, type a new UV set name each time you map. Alternatively, you can start with an empty UV set and then create UVs. To create an empty UV set 1 Select the object, then select Create UVs > Create Empty UV Set >

.

2 In the Create UV Set Name box, type the name of the empty set and click Create. 3 Select the new UV set (see Switch between UV sets on page 84). 4 Create UVs with one of the mapping operations or by copying.

Related topics ■


■

UV sets on page 11

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Create UVs > Create Empty UV Set on page 107

83

Switch between UV sets You can easily switch the UV sets that get applied to your polygon model. To switch between UV sets 1 Do one of the following: ■

In the UV Texture Editor, select UV Sets > UVsetName. UVsetName indicates the list of UV sets.

■

In the scene view, press the right mouse button on a mesh and choose UV Sets > UVsetName. UVsetName indicates the list of UV sets.

■

Select Create UVs > Set Current UV Set. In the window, type the name of the UV set you want.

Related topics ■

UV sets on page 11

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■


Duplicate, rename, or delete a UV set Select the UV set you want to rename, copy from, or delete. Do one of the following: ■

Select Create UVs > Copy UVs to UV Set This copies the current UV set to a new UV set.

■

Select Create UVs > Rename Current UV Set Type a new UV set name in the window that appears.

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Select Create UVs > Delete Current UV Set

Related topics ■

UV sets on page 11

84 | Chapter 4 UV sets

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Create UVs > Copy UVs to UV Set on page 108

Assign a texture to a UV set You assign textures to UV sets using the Relationship Editor. Select Window > Relationship Editors > UV Linking > UV-Centric to open the Relationship Editor’s UV set editing view. To...

Do this

To assign a texture to a UV set.

Click the UV Set in the left column, then click the texture in the right column so it’s highlighted.

To remove a texture from a UV set.

Click the UV Set in the left column, then click the texture in the right column so it’s not highlighted.

Temporarily keep textures from appearing in software renders.

From the Edit menu above the list of textures, choose one of the following: ■

Ignore Texture: hides the selected texture.

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Use Texture When Rendering: uses the selected texture.

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Isolate Texture: hides all textures but the selected one.

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Use All Textures When Rendering.7

Assign a texture to a UV set | 85

The Relationship Editor also provides easy access to several of the UV set editing operations in its Edit menu.

Related topics ■

UV sets on page 11

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Copy UVs from one UV set to another To copy UVs from one existing UV set to another 1 In the UV Texture Editor, select the UVs you want to copy. 2 In the UV Texture Editor, open the Polygons > Copy UVs to UV Set sub-menu and choose a UV set.


Notes ■

When polygon UV sets are copied with history, the source UV set is linked with the destination. Any changes made to the source UV set by using construction history, will influence the copied UV set. To avoid this issue, delete construction history after copying the UV set.

Related topics ■

UV sets on page 11

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Working with per-instance UV sets While you could always associate different instances of a particular shape with different materials, you can now associate different UV sets with different instances. This is very useful when baking shadows on instances of an object (for example, lighting a game level), or creating instances of a single shape with different textures (for example, a pile of boxes, some with holes in different locations, and so on). When the UV sets are per-instance, the term UV set family refers to the associated UV sets which apply to different instances. Within a given family, a single UV set may be applied to one or more instances. To create a per-instance UV map 1 Select a shape. 2 Select Create UVs > Create Empty UV Set >

.

You can choose to share this UV set (every instance has the UV set), Per Instance Shared (all selected instances share the new UV set), or Per Instance Unshared (all selected instances get a unique UV set). 3 Name your UV set as required. 4 Select another instance of the shape. 5 Right-click on the instance, select UV sets and make the per-instance UV set that you created the selected set.

Working with per-instance UV sets | 87

6 Select a UV mapping type under the Create UVs menu (such as Planar, Cylindrical or Spherical). Make sure that Create New UV Set is disabled in the mapping’s option window. A new UV map is create for the selected instance that shares the name of the current set. 7 Assign a shader to all instances of the mesh. 8 Right-click on an instance and select the UV Sets > UV Linking... Use the Relationship Editor to connect any of the per-instance sets to the color of the shader. Different (per-instance) UV mappings should now be displayed on your instanced objects when you render them or display them in the Scene view with Hardware texturing.

Example: Baking a single shadow map with per-instance UV sets In the following example, we’ll bake shadows to a single map using per-instance UV sets. At that point, we can delete lights in the scene. This workflow is useful for creating texture maps on objects for game levels. For more details about baking, see Lighting/shading > Batch Bake (mental ray) of the Shading guide. In this simple scene, there is a long cylinder to cast shadows, a directional light, a small plane with 16 x 16 subdivisions, and two additional instances of the plane. Setting up your scene 1 Create a long, skinny polygonal cylinder whose base is on the ground plane.


2 Create a small polygonal plane on the ground plane and from the polyPlane node, set Subdivisions Width and Subdivisions Height to 16 each. 3 Select the polygon plane and select Edit > Duplicate Special >

.

4 Set Geometry Type to Instance and select Apply twice to create two instances of the small polygonal plane (the instances will appear overtop of the original). 5 Position the planes one after another like a sidewalk.

6 Create a directional light (Create > Lights > Directional Light) and position it pointing slightly down and towards the cylinder and planes. 7 In the Attribute editor, change the Intensity of the light to 4.5. 8 Open the Shadows section and turn on Use Depth Map Shadows. 9 Change the shadow color to blue. 10 Render the scene using the mental ray renderer. Your render should look something like this:


You may need to adjust the direction of the light and re-render so that the shadow falls on each polygonal instance in a different location, as in the above render. Now we can create UV sets per instance on the planes. Creating per-instance UV sets 1 Select the three polygonal plane instances and in the Polygons menu set, select Create UVs > Create Empty UV Set >

.

2 In the Create UV Set Options dialog box, create a UV set named Sidewalk and select Per Instance Unshared. Then click Create. 3 Right-click on one of the polygonal plane instances and make Sidewalk the selected UV set by selecting UV Sets > Sidewalk (n). 4 Select all the polygonal plane instances, and create UVs by selecting Create UVs > Planar Mapping > ■

Fit Projection to: Bounding Box

■

Project from: Y axis

and selecting:

Make sure that Create new UV Set is turned off. 5 Click Project.


You’ve now created a per-instances UV set whose UVs don’t overlap in UV space. (You can use the UV Texture Editor to confirm this and move UVs if necessary.)

Now we’ll bake the shadows to a single UV map. Baking to per-instance UV sets 1 Select the three polygonal plane instances. 2 In the Rendering menu set, select Lighting/shading > Batch Bake (mental ray) >

.

3 Set the following: ■

Objects to bake: Selected

■

Bake to: Texture

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Bake shadows: on

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Use bake set override: on

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Color mode: Only light

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Bake to one map: on

4 Click Convert and Close. While the shadows are baked, you now have to connect the bake set to the UV map. 5 Right-click one of the instances and select UV Sets > UV Linking. 6 In the Relationship editor, link the Sidewalk(0) map to baked_inBake1.


The shadows are baked and properly linked. You can see this in the Scene view if you’re in Shaded mode (Hotkey: 6) or High-Quality rendering mode. 7 At this point, you can delete the light in your scene since its shadows have been baked to the UV textures on your polygonal instances.

Deleting per-instance UV sets Deleting UV sets works slightly differently now that there can be UV set families shared between instances. For example, a per-instance set family named myMap has two child sets. One is applied to multiple instances (instances a, b, and c) and one is applied only to instance d. It is the current UV set. If you select instance d, and select Delete Current UV Set, only the map on instance d is deleted. (The other UV map is used by unselected instances and is not deleted.) If you then select instance a and select Delete Current UV Set, the UV set is unshared from instance a, but still exists on instances b and c. To delete it


altogether, you can then select instances b and c and select Delete Current UV Set.

Limitations Per-instance UV sets do not support color sets or paint effects.

Edit NURBS UVs Maya provides limited support for editing the UV texture coordinates of NURBS surfaces within the UV Texture Editor. Edit NURBS UV mode is useful for games developers who use NURBS surface types in games applications and require the ability to modify an explicit UV set for subsequent export to a games engine. This feature does not provide support for editing NURBS UVs for use with texture mapping or image rendering features within Maya. Edit NURBS UV mode creates an explicit and unique UV set for the NURBS surface. The user switches between the implicit UVs for the NURBS surface and the explicitly created UV set. It is then possible to edit the explicit NURBS UVs on a limited basis. It is recommended that you create and edit the explicit NURBS UVs only when all editing and modification of the NURBS surface model is complete. See the Notes on page 94 and Edit NURBS UVs Limitations on page 94 below. For more information on the MELTM commands and flags that provide this functionality, see the nurbsUVSet, nurbsEditUV commands in the MEL guide. To edit UVs for a NURBS surface in the UV Texture Editor 1 In the scene view, select the NURBS surface that you want to create and edit explicit UVs for texturing. 2 Ensure that the construction history for the NURBS surface is deleted by selecting Edit > Delete All by Type > History. Deleting construction history prior to making any UV edits ensures that subsequent updates to the node dependency graph do not remove the UV edits you make to the explicit NURBS UV set. Do this only when you are sure you will no longer be required to edit the model (Save a copy of the model that contains construction history in case you need to revert back for any reason). 3 Turn off construction history while you work on the NURBS UVs using the Construction History on/off icon on the Status Line.

Edit NURBS UVs | 93

4 Open the UV Texture Editor by selecting Edit UVs > UV Texture Editor. The NURBS UVs that are implicitly created with the NURBS surface appear in the 2D view of the UV Texture Editor. 5 In the UV Texture Editor, right + click in the 2D view, and select Edit NURBS UV mode from the marking menu that appears. A UV set for the NURBS surface is explicitly created and displayed in the 2D view of the UV Texture Editor. The NURBS UV set created is based on the topology of the NURBS surface. 6 Change the selection method to UVs by doing one of the following: ■

Right + click in the scene view and select Surface UV from the marking menu.

■

Right + click in the 2D view of the UV Texture Editor, and select UV from the marking menu.

7 Select the UVs you want to modify in either the scene view or in the 2D view of the UV Texture Editor. 8 Using the transformation tools from the Toolbox (Move Tool, Rotate Tool, or Scale Tool), edit the position of the NURBS UVs in the UV Texture Editor.

Notes ■

Deleting the construction history on the NURBS surface is a requirement prior to creating and editing the explicit NURBS UVs. This ensures that updates to the dependency graph do not overwrite UV edits.

■

Modifying the NURBS surface topology in any way (that is, inserting an isoparm on the NURBS surface) after the explicit UV set has been modified will overwrite the unique NURBS UV set. The explicit NURBS UV set will be updated to take into account the changes to the topology, but any UV modifications will be lost.

Edit NURBS UVs Limitations ■

The explicit UV set created with this feature is unique for each NURBS surface. That is, unlike polygon and subdivision surface types, it is not possible to create multiple NURBS UV sets for a given NURBS surface.


■

The Maya renderers (software, hardware, mental ray for Maya, and so on) do not support explicit NURBS UVs. They are only capable of rendering the implicit UVs for NURBS.

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Construction history is not supported. That is, a user should plan their texturing workflow to occur after all edits and modifications to the model are complete. Changing the topology of the model after the NURBS UV set has been edited will overwrite the UV edits whenever the node dependency graph updates.

■

UV modification is limited to UV selection and transformation only (that is, move, rotate, and scale). It is not possible to select and modify the explicit NURBS UVs by patch or isoparm. The polygon and subdivision surface UV modification features do not work with the explicit NURBS UVs.

■

UV sharing is not supported. With explicit NURBS UVs a UV texture coordinate exists for each patch corner on the surface. A bounding box selection can be used to move interior NURBS UVs simultaneously.

Edit NURBS UVs | 95

96

UVs menu reference

5

Create UVs Create UVs > Planar Mapping Maps UV texture coordinates onto the selected surface mesh by projecting them along one direction from an imaginary plane.

Related topics ■


Create UVs > Planar Mapping > Fit projection to: By default, the projection manipulator is automatically positioned based on one of two settings: Best plane If you want to map UVs for a portion of the object’s faces, you can select Best plane and the projection manipulator snaps to an angle and rotation aimed directly at the selected faces. Bounding box This option works best when you are mapping UVs to all or most of an object’s faces. It snaps the projection manipulator to fit within the object’s bounding box. With this option on, you must choose one of the Project from directions to establish the orientation of the projection manipulator. Project from Choose an axis (X, Y, Z) so that the projection manipulator is aimed at the majority of the object’s faces. For example, a turtle model sitting

97

on the grid would have most of its faces pointing along the Y axis, while a horse model standing on the grid would have most of its faces pointing along the X or Z axis. Choose the Camera option if most of the model’s faces point somewhere that is not directly along the X, Y, or Z axis. This option positions the projection manipulator based on the current active view. Keep image width/height ratio Turn this option on to retain the width to height ratio of the image so that the image does not distort. Turn it off so that the mapped UVs fill the 0 to 1 coordinates in the UV Texture Editor. Insert projection before deformers The Insert projection before deformers option is relevant when the polygonal object has a deformation applied to it. If the option is turned off and the deformation is animated, the texture placement is affected by the change in vertex positions. This leads to “swimming” textures. Turning this option on applies the texture placement to the polygonal object before the deformation is applied to it. That is, the texture placement dependency graph node is inserted before the deformer dependency graph nodes and the texture “sticks” to the geometry even after the deformation. Create new UV set Turn this option on to create a new UV set and place the UVs created by the projection in that set. Type the name of your UV set in the UV Set name box.

Manually adjusting the projection manipulator You can use the manipulator handles to interactively adjust the UV map that gets projected or enter values to change the Projection Center, Rotation and Scale using either the Channel Box or the Attribute Editor. These values correspond to the manipulator handles that display when you map your texture onto the polygon. Projection Center The projection center defines the point of origin in the X, Y, or Z axis from where you can project a texture map. By default, this is the center of the selected faces in the X, Y, or Z axis. Rotate Type a value to rotate the projection in the 3D view around the X, Y, or Z axis which subsequently rotates the texture. Projection Width Sets the width (U) of the projection relative to the 3D projection axis. Projection Height Sets the height (V) of the projection relative to the 3D projection axis.

98 | Chapter 5 UVs menu reference

Image Center This value represents the center of the projected UVs. Changing this value translates the center accordingly. Rotation Angle This value changes the angle at which UVs are rotated in the 2D window. Drag the slider or enter a value to rotate the image. Image Scale This value represents the width (U) or the height (V) of the 2D map relative to the 2D center point.

Create UVs > Cylindrical Mapping Maps UV texture coordinates onto the selected objects by projecting them inward from an imaginary cylinder.

Related topics ■


Create UVs > Cylindrical Mapping > Insert projection before deformers This option is turned on by default. The Insert projection before deformers option is relevant when the polygonal object has a deformation applied to it. If the option is turned off and the deformation is animated, the texture placement is affected by the change in vertex positions. This leads to “swimming” textures. Turning this option on applies the texture placement to the polygonal object before the deformation is applied to it. Basically, the texture placement dependency graph node is inserted before the deformer dependency graph nodes and the texture “sticks” to the geometry even after the deformation. Create new UV set Turn this option on to create a new UV set and place the UVs created by the projection in that set. Type the name of your UV set in the UV Set name box.

Manually adjusting the projection manipulator You can use the manipulator handles to interactively adjust the UV map that gets projected or enter values to change the Projection Center, Rotation and Sweep using either the Channel Box or the Attribute Editor. These values correspond to the manipulator handles that display when you map your texture onto the polygon.

Create UVs > Cylindrical Mapping | 99

Projection Center The projection center defines the point of origin in the X, Y, or Z axis from where you can project a texture map. By default, this is the center of the selected faces in the X, Y, or Z axis. Rotate Type a value to rotate the projection in the 3D view around the X, Y, or Z axis which subsequently rotates the texture. Horizontal Sweep Use the slider or type a value to scale the projection around the polygonal object in the horizontal direction. This value corresponds to the Projection Scale Aperture handles on the manipulator. For instance, pull the Projection Scale Aperture handles all the way around the object until they meet. This is equivalent to entering 360 in the box. Vertical Sweep Use the slider or type a value to scale the projection around the polygonal object in the vertical direction. This value corresponds to the Projection Scale Aperture handles on the manipulator. For instance, pull the Projection Scale Aperture handles all the way around the object until they meet. This is equivalent to entering 360 in the box. Projection Height Scaling a projection enlarges or reduces the height (V) of a map relative to the 3D projection axis. Image Center This value represents the center of the projected UVs. Changing this value translates the center accordingly. Rotation Angle This value changes the angle at which UVs are rotated in the 2D window. Drag the slider or enter a value to rotate the image. Image Scale This value represents the width (U) or the height (V) of the 2D map relative to the 2D center point.

Create UVs > Spherical Mapping Maps UVs onto the selected objects by projecting them inward from an imaginary sphere.

Related topics ■


Create UVs > Spherical Mapping > Insert projection before deformers This option is turned on by default. The Insert projection before deformers option is relevant when the polygonal


object has deformation applied to it. If the option is turned off and the deformation is animated, the texture placement is affected by the change in vertex positions. This leads to “swimming” textures. Turning this option on applies the texture placement to the polygonal object before the deformation is applied to it. Basically, the texture placement dependency graph node is inserted before the deformer dependency graph nodes and the texture “sticks” to the geometry even after the deformation. Create new UV set Turn this option on to create a new UV set and place the UVs created by the projection in that set. Type the name of your UV set in the UV Set name box.

Manually adjusting the projection manipulator You can use the manipulator handles to interactively adjust the UV map that gets projected or enter values to change the Projection Center, Rotation and Sweep using either the Channel Box or the Attribute Editor. These values correspond to the manipulator handles that display when you map your texture onto the polygon. Projection Center The projection center defines the point of origin in the X, Y, or Z axis from where you can project a texture map. By default, this is the center of the selected faces in the X, Y, or Z axis. Rotate Type a value to rotate the projection in the 3D view around the X, Y, or Z axis which subsequently rotates the texture. Horizontal Sweep Use the slider or type a value to scale the projection horizontally around the polygonal object. This value corresponds to the Projection Scale Aperture handles on the manipulator. For instance, pull the Projection Scale Aperture handles all the way around the object until they meet. This is equivalent to entering 360 in the box. Vertical Sweep Use the slider or type a value to scale the projection vertically around the polygonal object. This value corresponds to the Projection Scale Aperture handles on the manipulator. For instance, pull the Projection Scale Aperture handles all the way around the object until they meet. This is equivalent to entering 360 in the box. Image Center This value represents the center of the projected UVs. Changing this value translates the center accordingly. Rotation Angle This value changes the angle at which UVs are rotated in the 2D window. Drag the slider or enter a value to rotate the image.

Create UVs > Spherical Mapping | 101

Image Scale This value represents the width (U) or the height (V) of the 2D map relative to the 2D center point.

Create UVs > Automatic Mapping Projects UV texture coordinates onto the selected object from multiple angles simultaneously. An Automatic Mapping Projection Manipulator is displayed around the selected object to facilitate more accurate UV projection.

Related topics ■


Create UVs > Automatic Mapping > Planes Selects the number of planes for the Automatic Mapping projection. You can choose a projection mapping based on shapes with 3, 4, 5, 6, 8 or 12 planes. The more planes used, the less distortion occurs and the more UV shells created in the UV Texture Editor. The number of planes that appear on the Automatic Mapping Projection manipulator directly relates to the number of planes set in this option.

Optimize for: Sets the optimization type for the automatic projection. Less distortion Projects all planes equally. While this method provides the best projection for any face, you may end up with more shells. It is particularly useful if you have a symmetrical model and you want the shells of the projection to be symmetrical. Fewer pieces Projects each plane until the projection encounters a projection angle that is not ideal. This can result in larger shells, and fewer of them. This is the default.


NOTE In some cases, setting the Optimize for setting to Less Distortion can produce a slightly different UV layout when you open the same file on another operating system. If this happens you can either: ■

Set Optimize for to Fewer pieces.

■

Keep the Less Distortion setting but delete history on the object (Edit > Delete by Type > History). This action assigns UVs directly to the surface.

Insert projection before deformers The Insert projection before deformers option is relevant when the polygonal object has a deformation applied to it. If the option is turned off and the deformation is animated, the texture placement is affected by the change in vertex positions. This leads to “swimming” textures. Turning this option on applies the texture placement to the polygonal object before the deformation is applied to it. Basically, the texture placement dependency graph node is inserted before the deformer dependency graph nodes and the texture “sticks” to the geometry even after the deformation.

Load projection Lets you specify a custom polygon object to be the projection object for automatic mapping. You must initially create the polygon object in object space (X, Y, Z). The Load Projection object must exist in the current scene. The projection object can form a cage around the object or be comprised of separate faces that intersect each other at its center. The faces of the projection object must have UV texture coordinates. It is recommended that you use separated faces. You can separate the faces for a polygon primitive using the Mesh > Extractfeature. NURBS and subdivision surfaces are not valid surface types for use with Load Projection. The maximum number of polygon faces that can be specified for a projection object is 31. You can translate any face from the Load Projection object along its normal with no affect on the resulting projection. However, scaling or rotating any face from the Load Projection object affects the resulting orientation and scale of the final UV projection. Changing the UV texture coordinates on the projection object also affects the resulting UV projection mapping that occurs. The Automatic Mapping projection manipulator updates to reflect the change in orientation whenever this occurs. Projection object Identifies the currently loaded projection object in the scene. You specify the projection object by typing the name of the projection object in this field. Alternatively, the name of the projection object will appear in this field when the desired object in the scene is selected and the Load Selected button is selected.

Create UVs > Automatic Mapping | 103

Load selected Loads polygon faces that are currently selected in the scene as the specified projection object. The specified faces are used to update the automatic projection manipulator. While the maximum number of polygon faces that can be specified for a projection object is 31, the recommended range is between 3 and 8. Project both directions When Project both directions is off (default), Load projection projects UVs on polygon objects whose normals point in roughly the same direction as the projecting plane of the Load Projection object. When Project both directions is turned on, the alignment of normals on both sides of the projection faces determines which objects will receive a projection from a particular projection plane. That is, the normals are projected outwards from both sides of the Load Projection object and the surfaces whose normals align are evaluated accordingly.

Shell layout Sets where the laid out UV shells will lie in UV texture space. Overlap Overlaps the resulting projection within the 0 to 1 UV texture space in the UV Texture Editor. Overlap is useful when the UV texture shells need to share the same texture. When the Load Projection option is turned on, Overlap becomes the default layout. Along U Positions the shells along the U axis. Into Square Positions the shells within the 0 to 1 texture space. This is the default. Tile Separates the resulting UV projections so they reside in a separate 0 to 1 UV space. Tile is useful when you anticipate additional editing or manipulation for the UV projections and need them to remain separated.

Scale mode Sets how the UV shells will be scaled within UV texture space. None Performs no scaling.


Uniform Scales the shells to fit the 0 to 1 texture space without changing the aspect ratio. This is the default. Stretch to Square Stretches the shells to fit the 0 to 1 texture space. The shells may become distorted.

Shell stacking Determines how the UV shells get stacked in relation to each other when laid out in the UV Texture Editor. Bounding Box Creates a rectangular bounding box around each UV shell, then stacks the shells based on the borders of the bounding boxes. The UV shells will have more space between them when this option is set. Shape Stacks the UV shells based on the boundaries of each individual shell. The UV shells can be more tightly arranged to fit into any available spaces when this option is set.

Spacing presets Maya puts a bounding box around each piece and lays out the shells so that the bounding boxes are very close together. If the shells end up positioned exactly next to each other, two UVs on different shells can share the same pixel and when painting with the 3D Paint Tool, overscanning can also cause the paint to spill onto the adjacent shell.

Create UVs > Automatic Mapping | 105

To avoid this situation, ensure that there is at least a pixel between the bounding boxes by selecting a spacing preset from this menu. Select a preset that corresponds to your texture map size. If you don’t know the size, select a smaller map, which will result in a larger spacing between adjacent shells in UV space. (The smaller your map in pixels, the bigger the UV spacing must be between bounding boxes.) Select Custom to set the size of the space as a percentage of the map size (in the Percentage Space box). Percentage space If you select Custom beside Spacing Presets, enter the size of the space between bounding boxes as a percentage of the map size. Create new UV set Turn this option on to create a new UV set and place the newly created UVs in that set. Type the name of the UV set in the UV Set Name box.

Create UVs > Create UVs Based On Camera Creates UV texture coordinates for the selected object based on the current camera view as a planar projection. That is, the camera view becomes the plane of projection.

Create UVs > Create UVs Based On Camera > Create new UV set Turn this option on to create a new UV set and place the newly created UVs in that set. Type the name of the UV set in the UV Set Name box.

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UV sets on page 11


Create UVs > Best Plane Texturing Tool Assigns UVs to the faces you select based on a plane computed from vertices you specify. NOTE It is important that you either select all faces before invoking the tool, or set the selection mask explicitly to Polygon. Otherwise selection problems can occur. Use the Best Plane Texturing Tool on on shape at a time. You can still use vertices from a different shape to define the plane.

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Create UVs > Assign Shader to Each Projection When Assign Shader to Each Projection is turned on, a shader with a checkerboard texture is assigned to the selected mesh as you project UV texture coordinates. This aids in determining the alignment of the UVs by providing a known visual reference. The default setting is off.

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Create UVs > Create Empty UV Set Creates a new, empty UV set on the current object. You can then create the UVs in the set using one of the mapping/projection methods. This feature is also available for use from the Polygons menu in the UV Texture Editor.

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UV sets on page 11

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Create UVs > Best Plane Texturing Tool | 107

Create UVs > Create Empty UV Set > Create UV Set name Type a name for the new UV set in the text field. UV Set Sharing You can choose to share this UV set (every instance has the UV set), Per Instance Shared (all selected instances share the new UV set), or Per Instance Unshared (all selected instances get a unique UV set).

Create UVs > Copy UVs to UV Set Creates a new UV set based on an existing UV layout or transfers a UV layout from one set to another. This feature is also available for use from the Polygons menu in the UV Texture Editor.

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UV sets on page 11

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Create UVs > Set Current UV Set Lets you specify which UV set you want to use for a particular polygon mesh. You specify which set you want by typing the name of the UV set in the text field that appears. This feature is also available for use from the Polygons menu in the UV Texture Editor.

Create UVs > Set Current UV Set... UV set name Type the name of the UV set you want to switch to in this text field.

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UV sets on page 11

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Create UVs > Rename Current UV Set Lets you rename the currently selected UV set. This feature is also available for use from the Polygons menu in the UV Texture Editor.

Create UVs > Rename Current UV Set... New UV set name Type the name of the UV set you want to switch to in this text field.

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Create UVs > Delete Current UV Set Deletes the currently selected UV set. This feature is also available for use from the Polygons menu in the UV Texture Editor.

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Create UVs > UV Set Editor The UV Set Editor lets you create and edit UV sets for multiple polygon meshes simultaneously. For more information see UV Set Editor on page 160.

Create UVs > Per Instance Sharing You can select shared instances, share instances, or make the selected instance curent.

Create UVs > Rename Current UV Set | 109

Edit UVs Edit UVs > Normalize Scales the UVs of the selected faces to within the 0 to 1 range of the UV texture space.

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Move, rotate, and scale UVs on page 35

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Edit UVs > Unitize on page 111

Edit UVs > Normalize > Use the following options as required to Normalize the UV texture coordinates.

Collectively Select Collectively to normalize the UVs for all selected faces collectively. That means the texture coordinates for all selected faces are “collectively” fit to the 0 to 1 texture space. This is the default.

Each face separately Select Each face separately to normalize the UVs for each selected face separately. That means the texture coordinates for each selected face are fit to a boundary of 0 to 1.


Preserve aspect ratio Turn this option on to scale the UVs uniformly along U and V. Turn this option off (the default setting) to stretch the texture to fit by scaling U and V non-uniformly. When you normalize texture coordinates, you scale the UVs of the selected faces. If Preserve Aspect Ratio is on, the scaling is guaranteed to be uniform on both the U and V axes. If turned off, the scaling will be different for the U and V axes.

Edit UVs > Unitize Repositions the UVs of the selected faces on the boundary of the 0 to 1 UV texture space as they appear in the UV Texture Editor.

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Layout UV shells on page 58

Edit UVs > Unitize > Create new UV set Turn this option on to automatically create a new UV set on the object to hold the unitized UVs. Enter a name for the new UV set in the UV Set name box.

Edit UVs > Flip Flips the positions of the selected UV shells either horizontally or vertically.

Edit UVs > Unitize | 111

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Edit UVs > Flip >

Direction Set the direction to flip the UVs of the selected shells: Horizontal or Vertical. The default is Horizontal. Coordinate Set Global as required to flip the UV shells in global UV space in the 0 to 1 texture space axis. Select Local to flip the UVs within the bounding box of the selected shells. The default is Local.


Edit UVs > Rotate Rotates the positions of the selected UVs.

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Edit UVs > Rotate | 113

Edit UVs > Rotate > Rotation angle The angle by which the UVs are rotated. The UVs rotate about their average center.

Edit UVs > Grid Repositions any currently selected UV to its nearest grid intersection in UV texture space.

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Edit UVs > Grid > Map size presets Sets the Grid U and Grid V options to common square texture sizes. Change the Grid U and Grid V sliders or enter values to use a different or non-square size. Grid U The number of grid lines horizontally (in the U dimension of texture space). Grid V The number of grid lines vertically (in the V dimension of texture space).

Move UVs to The options available are: Pixel border Snaps UVs to the nearest grid intersection. Pixel center Snaps UVs to the nearest midpoint between grid lines.

Edit UVs > Align Repositions any selected UVs so they are aligned to a particular U or V value based on the options setting.


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Edit UVs > Align > Align selected UVs to Sets whether the selected UVs are aligned to the left (minimum U), right (maximum U), bottom (minimum V), or top (maximum V).

Edit UVs > Warp Image Modifies a texture image by comparing two UV sets on a single polygonal mesh and produces a new bitmap image. To use this feature you must specify a source image, as well as a source and destination UV set for the model from which the UVs will be referenced for the image manipulation. Warp Image produces a new target image as the result.

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Copy UVs and color attributes between polygons on page 80

Edit UVs > Warp Image > These are the descriptions for the options in the Warp Image Options window. Source image name Specifies the name and file path of the image that is input for warp modifications. New image name Specifies the name and file path of the final image that is output from the warp calculations.

Background mode Background mode determines how colors are interpolated at the texture edges. When warping an image, occasionally some of the pixels along texture edges are missed. As a result, areas of the polygon mesh may not be properly covered as the background color shows through. The Background mode and Background color options helps manage this situation by allowing you to

Edit UVs > Warp Image | 115

specify a color to apply to the background. You can specify a fixed color that contrasts with the original source image so you can easily determine the locations of the pixel gaps or attempt to hide the gap using a color that is determined from the texture map. Automatic Extrapolates colors from the pixels on the related texture map to automatically minimize colors showing through. The results depend on the texture map. Fixed color Uses the color specified in the Background Color setting. Background color Specifies the color used for the Background mode. This can also be useful if you want to import the file texture into an image editing software application, and want a special key (color) to select the background for processing. File format Specifies the image file format for the new image that is created as a result of the Warp Image modifications. File formats include PIX, ALS, IFF, TIFF, CINEON, EPS, GIF, JPG, YUV, RLA, SGI, TGA, and BMP. Source UV set Specifies the polygon UV set that is referenced for warp modification. Destination UV set Specifies the polygon UV set that is used as a target when determining where to modify the final warped image. X resolution Specifies the X-axis resolution for the resulting warped image in pixels. The default X resolution is 256. Y resolution Specifies the Y-axis resolution for the resulting warped image in pixels. The default Y resolution is 256. Overwrite existing file When Overwrite Existing File is turned on (default), the target image overwrites a file of the same name if it exists in that location. When Overwrite Existing File is turned off and a file exists of the same name as specified in the New Image Name option, the Warp Image operation will quit without producing an image. Bilinear filtering When Bilinear Filtering is turned on (default), the target image is anti-aliased by averaging the colors of adjacent pixels. When Bilinear Filtering is used the resulting new image may be softer with less contrast as a result of the anti-aliasing that occurs. When Bilinear Filtering is off, a point sampling method for anti-aliasing is used that produces a sharper image with more contrast. Additional post-processing of the image may be necessary. Include alpha Specifies whether the alpha channel is incorporated into the Warp Image calculations. When the option is turned off the Alpha channel information is discarded.


Tiled When the Tiled option is turned on (default) the source image is repeated in U and V directions. For example, the UVs that extend beyond the UV range wrap to the other side. When Tiled is turned off, pixels that reside outside of the 0 to 1 UV range are ignored by the Warp Image feature. NOTE Tiling a warped image has implications if the wrapped UVs overlap with other UVs as a result. The Warp Image feature will have trouble determining where the pixel should be assigned in the areas of overlap and unpredictable results will occur in the final image. For that reason, UVs should be laid out so they do not tile. If they must tile, they should tile without overlapping.

Edit UVs > Map UV Border Repositions border UVs on a selected UV shell to a square or circle within the 0 to 1 range of the UV texture space. You can move the UVs on the border of a UV shell out to the edges of the 0 to 1 texture space (square), or to a circle inscribed within the 0 to 1 range. You can optionally scale the edges proportionally as you move the border UVs. Map UV Border is useful for untangling borders before you use Relax UVs to untangle interior UVs.

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Edit UVs > Straighten UV Border on page 120

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Edit UVs > Map UV Border > Border target shape Select the shape type that you want to map the UV border to (Square or Circle). Square The Square option maps the border UVs along the axes of the 0 to +1 texture range so the UV shell borders appear in a square shape. Square makes best use of texture space but can result in faces having zero or very little texture space around the UV border.

Edit UVs > Map UV Border | 117

Circle The Circle option maps the border UVs about a circle that is inscribed within the 0 to +1 region. Circle uses texture space less efficiently because of the unused corner regions.

Automatic Turn on Automatic to map the UV border automatically in a shape that approximates the best use the texture space while maintaining the world-space relationships between edges. Preserve original shape Determines how closely the border mapping will match the selected Border Target Shape. Use the slider or enter a value between 0 and 1 to control the blend of the existing UV border with the specified Border Target Shape. A value of 0 produces a UV border mapping that is closest to the specified target shape (Square or Circle). A value of 1 produces a border that closely represents the world-space relationships between edges, but can result in concave areas along the border—these will produce overlapping interior UVs once relaxed.


NOTE Map UV Border may not be able to find a unique border with non-manifold geometry. If you have a piece of non-manifold geometry, any particular UV may be in more than one border/shell, so it does not uniquely determine a flat piece of mesh to relax. Map UV Border will find a boundary and map it, but you can't control which one it will get. To work around this you can cut the UVs along the non-manifold edges to make sure that they're “flat”, or use Cleanup to eliminate the non-manifold areas first.

Edit UVs > Map UV Border | 119

Edit UVs > Straighten UV Border Untangles the border of the currently selected UV shell, such as an edge that loops around itself. Straighten UV Border provides more control than the Map UV Border operation in these circumstances.

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Edit UVs > Map UV Border on page 117

Edit UVs > Straighten UV Border > Curvature Pushes the selected border area outward or inward by the specified amount. A value of zero forces the edge to be straight. Each Curvature unit is .01 on the UV coordinate scale. Maya curves the border outward or inward depending on whether the value is positive or negative. However, you cannot tell in advance whether to use positive or negative. With the polyStraightenUVBorder node opened in the Channel Box or Attribute Editor, try positive and negative values and check the results in the UV Texture Editor. Preserve length ratio Controls the size of UV texture edges when straightened. Set to one, Maya preserves the original edge lengths. Set to zero, Maya averages the lengths. Values between zero and one change the length proportionally. Blend original shape Affects the shape of the straightened border by blending it with the original border shape. You can use this setting to constrain the effect of the above two settings. Set to one, Maya keeps the original shape and overrides the other settings. Set to zero, Maya does not consider the original shape when straightening. Values between zero and one proportionally blend the original shape with the curvature created by the other settings.

Fill gaps in selection The Fill gaps in selection options helps you straighten UVs that are missing from your selection because they are difficult to select. UV gap tolerance The UV Gap Tolerance setting is the threshold of when Maya selects and straightens the unselected UVs. For example, if there are three unselected UVs in the middle of two selected UVs, UV Gap Tolerance must be 3 or higher in order for Maya to select and straighten the middle UVs. The following illustration shows an example.


Edit UVs > Relax Automatically untangles and evens out the spacing between UV texture coordinates. You can choose to pin the border UVs so they remain in the same position while relaxing other UVs, or pin the selected or unselected UVs while relaxing any other UVs.

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Edit UVs > Relax > Pinning Use the following options to relax only selected portions of the UV shell. Pin UV border Turn this option on to maintain the position of the border UVs. This is the default.

Edit UVs > Relax | 121

Pin UVs Selet which UVs to pin. Pin selected UVs Turn this option on to maintain the position of selected UVs. For example, if you want more texture space for an area on a face with very dense UVs, you could select these UVs, scale them up, pin them, then relax the rest of the UVs to eliminate any overlapping you may have introduced during the scale. Pin unselected UVs Turn this option on to maintain the position of the unselected UVs. This option is useful for relaxing only the selected UVs.

Edge weights Select how the UV relax operation affects edges. Uniform Attempts to make all of the edges the same length. This is the default.


World space Attempts to retain the original world-space angles (subject to the restrictions of the pinned border). Maximum iterations Enter the number of relaxation iterations that will be performed on the UVs—ideal UV relaxation is subjective and iterative.

Edit UVs > Unfold The Unfold feature lets you unwrap the UV mesh for a polygonal object while trying to ensure that the UVs do not overlap. Unfolding UVs helps to minimize the distortion of texture maps on organic polygon meshes by optimizing the position of the UV coordinates so they more closely reflect the original polygon mesh. For example, if the initial shape of the UVs results in a distorted texture pattern on the surface mesh, you can use the Unfold feature to minimize the distortion because it attempts to maintain the UV’s relationship relative to the original surface mesh.

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Unfold a UV mesh on page 65

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UV unfolding workflow tips on page 70

Edit UVs > Unfold > These are descriptions for the options in the Unfold Options window. Weight solver towards A bias setting that determines the weighting between two unfold solver types: local and global. When Weight Solver towards is set to 0 (default) a local solver is used for the unfolding calculations. When the Weight solver towards is set to 1 a global solver is used for the unfolding calculations. When the Weight solver towards is set anywhere between 0 and 1, the unfolding results are based on the combined solver calculations. A Weight Solver towards setting of 0 is recommended for the majority of unfolding operations and provides the quickest results. Some polygon configurations can cause the Unfold feature to produce an undesired tapering effect on the unwrapped result. For example, the tapered

Edit UVs > Unfold | 123

shape from the thigh towards the ankle on a character’s pant leg may result in a more exaggerated tapering as a result of how the local solver works when it unfolds the UVs. When this occurs, the results can usually be improved by performing additional unfold operations with the Weight solver towards setting set to a value above 0 so that the global solver is taken into account. The unfold operation will take substantially longer, but the tapering effect will be reduced. Once the scale is more uniform, you can carefully pin UVs to control areas that were previously at different scales to ensure they don’t revert back. Once the UVs are pinned, you can perform subsequent unfold operations with the Weight solver towards setting at 0. For an example of how this works see Solver weighting example on page 126.

Optimize to original Specifies which polygon comparison method is used for the unfolding operation. This setting is only available when the Weight solver towards setting is greater than 0 and can be biased towards two comparison methods: Face area Compares polygons by comparing the area of individual UVs to the original faces of the polygon mesh. Edge length Uses a method that compares the length of the edges of the UVs to the face edges of the original polygons. When the Face area/Edge length bias setting is set to 0.5 (the default) both methods of comparison have equal weighting in determining the final result. In general, this is a good starting point for the majority of unfold calculations. Polygon meshes with high areas of curvature can have better unfold results when the bias is set towards Face area. This setting minimizes the buckling of the texture map in the areas of curvature. However, if the bias setting is set fully towards Face area, a shearing effect on the texture can occur as a result of the calculations attempting to work within the constraints specified by the Face area bias.

Pinning Use the following options to unfold only selected portions of the UV shell. Pin UV border Maintains the position of the UVs along the poly shell’s border edge during the unfold operation. Use this option when you want the shell’s border edge to be unaffected by the unfold operation.

Pin UVs Lets you perform the Unfold operation but pin specific UV combinations. Pin selected UVs Maintains the position of only the selected UVs during the unfold operation.


By default, Unfold repositions all of the selected UVs during the unfold operation and the unselected UVs remain pinned. This option reverses that default behavior. This option can be useful when specific UVs are already in a desired pattern when unfolded and you need some of the UVs to remain unaffected by subsequent unfold operations. Pin unselected UVs Maintains the position of only the unselected UVs during the unfold operation. This is the default setting. When this option is on, Unfold repositions all of the selected UVs during the unfold operation and the unselected UVs remain pinned.

Unfold constraint Specifies how the unfolding of the UVs will be constrained as they are unfolded. None The UVs will unfold freely in any direction during the unfold operation. Vertical The UVs will be constrained in the vertical direction as they appear in the UV Texture Editor. Horizontal The UVs will be constrained in the horizontal direction as they appear in the UV Texture Editor. Maximum iterations Specifies the maximum number of repeated calculations allowed for the unfold solver when calculating the final unfolded result if the Stopping threshold value has not been reached. When this maximum occurs, the unfold calculations will stop. TIP You can stop the unfold calculations at any time by pressing Esc. If the calculations appear to stop prematurely, it simply means that the Stopping threshold has been reached. The default is 5000. Setting the Maximum iterations higher than 5000 causes the Unfold feature to calculate further towards the Stopping threshold and lengthens the time for the unfold calculation. If the Weight solver towards setting is any value above 0, you may wish to initially set Maximum iterations to a smaller value such as 50 for your initial unfold iteration. Stopping threshold Specifies a mathematical threshold to stop the unfold calculations. The value is based on an internally computed relative percentage of overall improvement when comparing the angles, distances, and areas between the original polygon mesh and the unfolded result. The unfold calculations will progress until this percentage threshold is reached or until the maximum number of iterations specified by the Maximum iterations setting is reached.


Setting the value smaller than 0.001 will result in longer times when unfolding. If time is not of concern, you can also set the Stopping threshold to 0 and allow the Unfold feature to calculate the best result. Rescale Resizes each final unfolded UV shell to match the Scale Factor once the unfold calculations are complete. It accomplishes this by first determining the surface area of the polygon mesh in object space (XYZ), comparing it to the unfolded UV meshes' surface area, and then scaling the UV mesh by that value. This option is useful when multiple shells are unfolded and you require them to have a similar scale between them. Scale factor A ratio value that determines the amount of Rescale. A Scale Factor greater than 1 results in the UV mesh being scaled larger, whereas a Scale factor less than 1 results in the UV mesh being scaled smaller. For example, if a polygon mesh had a unit size of 1 in the scene view, a Scale factor setting of 0.02 would result in the corresponding UV mesh having a unit size of 0.02 in the UV Texture Editor. Keep history When Keep History is turned on, the Unfold feature automatically recalculates the UV texture coordinate positions for the shell whenever the polygon model’s mesh is changed. This provides an effect where the texture appears to be distorted inwards or outwards along the surface when the mesh is deformed. Turning Keep History on can result in long computation times when the polygon object is animated thereby affecting interactive performance. It should be turned on only when you specifically want this special effect to occur and are aware of the impact on interactive performance in your scene as a result. The default setting is off.

Solver weighting example The following example demonstrates how changing the Weight solver towards option in combination with pinning and aligning UVs helps to control the unfolded UV layout and the texture mapping that results. ■

A barrel shaped polygonal object is texture-mapped with a checker texture. Using the Unfold feature and performing an initial unfold with the Weight solver towards option set to 0 (the default) initially produces a tapered UV layout in the UV Texture Editor. The resulting texture map is skewed and distorted on the object.


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A second unfold operation is performed with the Weight solver towards option at 0.6. This unfolds the UVs in a more global manner and reduces the tapering that previously occurred. The UV layout is more predictable, but there is some overlap of UVs in the lower left corner of the UV mesh resulting in overlap on the texture.


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Repositioning and pinning the corners of the UV mesh and performing another unfold with the Weight solver towards set to 0 further relaxes the UVs and removes the overlapping region.

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The top and bottom rows of UVs are aligned and a final unfold operation is performed with the Weight solver towards option set to 0 with the borders pinned.


Edit UVs > Layout Repositions the UV shells for selected objects so their arrangement is improved. The desired workflow is generally to lay out UV shells so they are not overlapping.

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World space, object space, and local space

Edit UVs > Layout > The default settings give the best results in most situations.

Layout Objects Select the manner in which you want to layout the UV shells.

Edit UVs > Layout | 129

Per object (overlapping) When multiple objects are selected in the scene this option specifies to lay out the UV shells for each object individually within the UV Texture Editor. Single object or multiple objects (non-overlapping) Specifies the multiple UVs to be positioned in the UV Texture Editor as if it were one single object.

Prescale Scales the area of the UV Shell proportional to either the surface area of the selected objects in object space or world space before laying out the UVs. Prescale is usually combined with Uniform Scale mode to scale UVs from multiple objects into a single UV region. Prescale is only available when Layout Objects is set to Single or Multiple Objects (non-overlapping). None No prescaling occurs. Object Automatically scales the UV shell to accommodate the selected objects’ surface areas in object space. For example, the UV Shells for a scene consisting of 5 spheres of radius 1 will appear equal in size using the Object setting regardless of their individual scaling. Scaling only affects the objects’ size in world space.

World Automatically scales the UV shell to accommodate the selected objects’ surface areas in world space. For example, the UV shells for a scene consisting of 5 spheres of radius 1, will appear according to their individual scale sizes.


Separate shells Specifies how you want to cut and separate overlapping UV shells. Off Does not separate overlapping UV shells. Only the Scale option has an effect. Folds Separates only shells where the surface normals of overlapping shells point in opposite directions. This method is faster, especially for larger models. However, you may be left with overlapping UVs. All intersecting Separates all shells where the UVs overlap. This is the default. Flip reversed Flips UV shells that have normals pointing in opposite UV winding order.

TIP If your model is symmetrical (for example, a character’s face), you can save texture space by turning this option off and superimposing the UV shells so they occupy the same texture space.

Shell Layout Specifies where the UV shells will lie in UV texture space. None Does not lay out UV shells after they have been cut. Some shells may lie on top of others.


Along U Positions the UV shells along the U axis. Into Region Positions the UV shells to lie within the 0 to 1 texture space. This is the default setting.

Scale mode Select how you want the UV shells scaled within the UV texture space. None Performs no scaling. Uniform Scales the shells to fit the 0 to 1 texture space without changing the aspect ratio. This is the default. Stretch to region Stretches the UV shells to fit within the 0 to 1 texture space. The UV shells may become distorted as a result.

Shell stacking Determines how the UV shells get stacked in relation to each other when laid out in the UV Texture Editor. Bounding box Creates a rectangular bounding box around each UV shell, then stacks the shells based on the borders of the bounding boxes. The UV shells will have more space between them when this option is set. Shape Stacks the UV shells based on the boundaries of each individual shell. The UV shells can be more tightly arranged to fit into any available spaces when this option is set.

Rotate Allows the UV texture shells to be rotated in order to better fit the UV texture space. None Specifies that the UV shells will not be rotated. 90 degrees Specifies that some UV shells can be rotated by 90 degrees to maximize the space within the 0 to 1 UV texture space.


Free Rotates the UV shells so they are oriented vertically in the UV Texture Editor based on their longest axis. This aids the Layout feature in packing the shells more densely, thereby maximizing UV texture space. Spacing presets Layout UVs creates a bounding box around each UV shell and then lays out the UVs so that the individual bounding boxes are positioned close together. Sometimes when the borders of two UV shells are positioned very close to each other, the two UV shells may end up sharing the same pixels on a texture map. When this situation occurs, a portion of one texture may bleed onto another or may wrap incorrectly on the surface, resulting in visual artifacts. When painting a texture, overscanning can also cause the paint to spill onto the adjacent piece.

To avoid this situation, you’ll want to specify a spacing preset to ensure that there is at least one pixel separating the individual UV bounding boxes. Select a preset that corresponds to your texture map size. If you don’t know the size, select a smaller map, which will result in a larger spacing between adjacent shells in the UV space. (The smaller the map in pixels, the bigger the UV spacing must be between bounding boxes.) Select Custom to set the size of the space as a percentage of the map size (in the Percentage space box) and enter a distance value that is appropriate for your texture map. Percentage space When the Spacing presets is set to Custom you can specify a distance measurement to specify the space between bounding boxes as a percentage of the map size. Region Preset A set of common settings for Scale U, Scale V, Offset U and Offset V. The following table outlines the presets. Label

Scale U

Scale V

Offset U

Offset V

Bottom Half

1.0

0.5

0.0

0.0

Top Half

1.0

0.5

0.0

0.5

Left Half

0.5

1.0

0.0

0.0


Label

Scale U

Scale V

Offset U

Offset V

Right Half

0.5

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Scale U Lets you set the scale of the UV mapping in the U direction. You can use the Offset in conjunction with the Scale to define the area on your model upon which your texture is laid out. Scale V Lets you set the scale of the UV mapping in the V direction. You can use the Offset in conjunction with the Scale to define the area on your model upon which your texture is laid out. Offset U Lets you set the UV mapping so that each UV is a specific distance in the U direction from its default position at the lower left corner of the UV layout region. You can use the Offset in conjunction with the Scale to define the area on your model upon which your texture is laid out. Offset V Lets you set the UV mapping so that each UV is a specific distance in the V direction from its default position at the lower left corner of the UV layout region. You can use the Offset in conjunction with the Scale to define the area on your model upon which your texture is laid out.

Edit UVs > Cut UV Edges Splits UVs along the selected edges creating new texture borders as a result. This feature is also available from the toolbar of the UV Texture Editor.


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Edit UVs > Merge UVs on page 136

Edit UVs > Split UVs Separates UVs from each other along the edges connected to the selected UV points, creating borders. This feature is also available from the toolbar of the UV Texture Editor.

Edit UVs > Sew UV Edges Attaches UVs along the selected borders, but does not move them together in the UV Texture Editor view. This feature is also available from the toolbar of the UV Texture Editor.

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Edit UVs > Move and Sew UV Edges on page 135

Edit UVs > Move and Sew UV Edges Move and Sew UV Edges combines separate UV shells along their selected border edges by moving one selected UV shell (the smaller one) to the other selected UV shell (the larger one) and merging the selected edges together so that one UV shell results. Move and Sew UV Edges is useful for quickly joining together separate UV shells produced by Automatic Mapping or the Layout

Edit UVs > Split UVs | 135

UVs features. This feature is also available from the toolbar of the UV Texture Editor.

There are two options for moving and sewing UV shells: manually or automatic. The default Move and Sew UV Edges behavior is to manually select the edges you want to join and then execute the feature. When the Limit shell size option is turned on, smaller shells are moved and sewn automatically to the larger ones based on the Number of faces setting value.

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Edit UVs > Merge UVs on page 136

Edit UVs > Move and Sew UV Edges > Limit shell size When this option is off, Move and Sew UVs only moves and sews the selected edges. When this option is on, Move and Sew UVs automatically moves and sews together any selected shells below the size set in Number of Faces. Number of faces When Limit shell size is on, this setting specifies the maximum number of faces in each shell. Larger numbers result in fewer shells. After performing a Move and Sew operation, you can select the history node (polyMapSewMove) in the Channel Box and adjust the Number of Faces until you achieve the results you want.

Edit UVs > Merge UVs Use Merge UVs to merge together separate UV shells. Merge UVs has a similar effect to Sew UVs. However, Merge UVs is better suited to merging shells when the polygon has non-manifold geometry. For example, when you have three UV shells that all share an edge because the geometry is nonmanifold, Merge UVs can combine two of the UV shells without affecting the other. If you used Sew UVs in this example, all shells would be combined because they all share an edge.


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Edit UVs > Cut UV Edges on page 134

Edit UVs > Merge UVs > Threshold Set the Threshold value to set the maximum distance within which selected UVs will be merged. Any UVs in the selection that exceed this distance will not be merged.

Edit UVs > Delete UVs Removes the UVs from the selected face(s) on a mesh. If you want to map textures onto the areas of the surface mesh where the UVs have been deleted, you will need to re-map or re-project the UVs using the UV projection mapping features.

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Delete UVs on page 43

Edit UVs > UV Texture Editor Displays the UV Texture Editor. For more information see UV Texture Editor reference on page 139.

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UV Texture Editor UV Texture Editor reference The UV Texture Editor (Window > UV Texture Editor or Edit UVs > UV Texture Editor) lets you view and interactively edit UV texture coordinates for polygons and subdivision surfaces. You can select, move, scale, and generally modify the UV topology for a surface very much like you work with other modeling tools within Maya. You can also view the image associated with the assigned texture map as a backdrop within the UV Texture Editor and modify the UV layout to match as required. Items in the UV Texture Editor can be selected from either the menu bar or from the graphical toolbar. For more information on the UV Texture Editor options see: ■


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Delete UVs on page 43

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Move tool (in UV texture editor) on page 163

UV Texture Editor menu bar These are descriptions of the menu items in the UV Texture Editor.

Polygons menu Polygons > Copy UVs Copies the selected UVs for a selected face to the clipboard so they can be copied (pasted) to another face. See Mesh > Clipboard Actions > Copy Attributes.

Polygons > Paste UVs Pastes UVs that were previously copied to the selected face. See Mesh > Clipboard Actions > Paste Attributes.

Polygons > Create Empty UV Set Creates a new, empty UV set on the current object. You can then create the UVs in the set using one of the mapping/projection methods. See Create UVs > Create Empty UV Set on page 107.

Polygons > Copy UVs to UV Set Use the items in this submenu to create a UV set based on an existing UV layout or transfer a UV layout from one set to another. See Create UVs > Copy UVs to UV Set on page 108.

140 | Chapter 6 UVs windows and editors reference

Polygons > Set Current UV Set Lets you select a specific UV set. See Create UVs > Set Current UV Set on page 108.

Polygons > Rename Current UV Set Lets you rename the currently selected UV set. See Create UVs > Rename Current UV Set on page 109.

Polygons > Delete Current UV Set Deletes the currently selected UV set. See Create UVs > Delete Current UV Set on page 109.

Polygons > Normalize Scales the UVs of the selected faces to within the 0 to 1 texture space. See Edit UVs > Normalize on page 110.

Polygons > Unitize Places the UVs of the selected faces on the boundary of the 0 to 1 texture space. See Edit UVs > Unitize on page 111.

Polygons > Flip Flips the positions of the selected UVs. See Edit UVs > Flip on page 111. This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Polygons > Rotate Rotates the positions of the selected UVs by a specified number of degrees. See Edit UVs > Rotate on page 113. This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Polygons > Cycle UVs Rotates the U and V values of the selected polygon.

UV Texture Editor menu bar | 141

This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Polygons > Best Plane Texturing Tool Assigns UVs to the faces you select based on a plane computed from vertices you specify. See Create UVs > Best Plane Texturing Tool on page 107.

Polygons > Grid Moves every selected UV to its nearest grid intersection in texture space. See Edit UVs > Grid on page 114. This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Polygons > Align Aligns the positions of the selected UVs. See Edit UVs > Align on page 114. This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Polygons > Warp Image Modifies a texture image by comparing two UV sets on a single polygonal mesh and produces a new bitmap image. See Edit UVs > Warp Image on page 115.

Polygons > Map UV Border Moves UV borders to the edges of 0 to +1 texture space. See Edit UVs > Map UV Border on page 117.

Polygons > Straighten UV Border Untangles the border of a UV texture shell, such as an edge that loops around itself. See Edit UVs > Straighten UV Border on page 120.

Polygons > Relax Spreads out all UVs to make them easier to work with. See Edit UVs > Relax on page 121.


This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Polygons > Unfold Lets you unwrap the UV mesh for a polygonal object while the feature attempts to ensure that the UVs do not overlap. See Edit UVs > Unfold on page 123.

Polygons > Layout Attempts to rearrange the UV shells into a cleaner layout, based on the settings in the Layout UVs option box. See Edit UVs > Layout on page 129. This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Polygons > Cut UV Edges Separates UVs along the selected edges, creating borders. See Edit UVs > Cut UV Edges on page 134.

Polygons > Split UVs Separates UVs from each other along the edges connected to the selected UV points, creating borders. Shortcut for the texture editor’s Edit UVs > Split UVs. This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Polygons > Sew UV Edges Attaches UVs along the selected borders, but does not move them together in the texture editor view. See Edit UVs > Sew UV Edges on page 135. This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Polygons > Move and Sew UV Edges Attaches UVs along the selected borders, and moves them together in the texture editor view. See Edit UVs > Move and Sew UV Edges on page 135. This item is also found on the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.


Polygons > Merge UVs Merges together separate UV shells. See Edit UVs > Merge UVs on page 136.

Polygons > Delete UVs Removes the selected UVs from the mesh. You will need to re-map or re-project the UVs in order to map textures onto the affected areas. See Edit UVs > Delete UVs on page 137.

Polygons > UV Snapshot Saves an image file of the current UV layout. You can then paint on this image in a painting program or use this image as a background reference layer for texture work in an image editor such as Adobe® Photoshop®. See Save an image of the UV layout on page 48. An option window appears with the following controls: File Name You can save the file anywhere inside or outside of your project. Maya automatically assigns the file extension based on the image format you select. Size X, Size Y Sets the dimensions of the exported image. Use the same dimensions you want for the file texture you are about to create. If you are not sure, use the default size; you can scale the exported image later in your paint program. Keep Aspect Ratio The aspect ratio is the ratio of Size X to Size Y. With it turned on, you can change one size slider and Maya automatically adjusts the other size value to keep the same ratio. If you need to change the aspect ratio, turn off this option temporarily and adjust one of the sizes. Color Value Sets the color of the UV patches in the exported image. The background of the snapshot is black; therefore, the Color Value should be white or another contrasting color. You can click the box to open the Color Chooser. Anti-alias Lines Controls whether lines in the output image have anti-aliasing. Image Format Use an image format that your paint program can read. If you require an alpha channel while painting, use TIFF or a similar format. UV Range Normal (0 to 1) specifies the range between 0 and 1. When this option is set (default), only the UVs appearing in the 0 to 1 area are included in the 2D image that gets output. (This was the option previous to Maya version 7.)


Entire Range specifies that a 2D image will be output that covers all displayed UVs regardless of their position within UV space. That is, if the UVs lie outside the 0 to 1 range, they will still be included in the UV snapshot image. User Specified allows you to customize the UV range that will be output by specifying minimum and maximum values for U and V. This is useful when you need to output an image of a specific UV shell or a specific region within the UV Texture Editor.

Subdivs menu The items in this menu are used for editing UVs on subdivision surfaces.

Subdivs > Cut UV Edges Separates UVs along the selected edges, creating borders. See Edit UVs > Cut UV Edges on page 134.

Subdivs > Layout Tries to move the UVs into a cleaner layout. See Edit UVs > Layout on page 129.

Subdivs > Move and Sew UV Edges Attaches UVs along the selected borders, and moves them together in the texture editor view. See Edit UVs > Move and Sew UV Edges on page 135.

Subdivs > UV Snapshot Saves an image file of the current UV layout. For more information see Polygons > UV Snapshot on page 144.

View menu View > View Contained Faces A UV selection filter that displays only the UV faces associated with the currently selected UVs in the UV Texture Editor.

View > View Connected Faces A UV selection filter that displays the UV faces associated with the currently selected UVs as well as the UV faces immediately connected to those UV faces.


View > View Faces of Selected Images A UV selection filter that displays the UV faces associated with the currently selected texture image in the UV Texture Editor (Textures > filename).

View > Isolate Select submenu Lets you show only a subset of all UVs, with the ability to add to and subtract from the isolated subset. See Display a subset of UVs on page 33

View > Grid Shows or hides the texture coordinate grid. Choose View > Grid > the grid options. See Use the UV Texture Editor grid on page 47

to set

Length and Width Controls the overall size of the grid, measured in UV coordinates. The Length and Width is set to 1 (one) by default, because you typically want UVs to fit within the 0 to 1 range and this setting clearly shows the 0 to 1 range. Grid Lines Every Sets the spacing between grid lines. Grid lines appear in increments based on the decimal value you specify. This setting affects where UVs snap if you use the Snap to Grid feature. Subdivisions Sets the number of lines between each grid line. By default, subdivision lines do not show; you must turn on Subdivision Lines for them to appear. Display Axes, Grid Lines, Subdivision Lines, Grid Numbers Displays or hides items within the grid.

View > Toolbar Shows or hides the texture editor toolbar. See the toolbar section below.

View > Frame All Pans and zooms the texture editor view to show the entire UV set.

View > Frame Selection Pans and zooms the texture editor to show the selected UVs.


Select menu The items in this menu are also available on a marking menu when you are working in the UV Texture Editor. Press ctrl + the right mouse button to access them.

Select > Select Contained Faces Selects the faces contained by the current selection of UVs, edges, or vertices.

Select > Select Connected Faces Selects all faces that share the currently selected UVs, edges, or vertices.

Select > Select Shell Selects the entire UV shell containing the current selection.

Select > Select Shell Border Selects the UVs along the border of the UV shell containing the current selection.

Select > Select Shortest Edge Path Tool Selects the shortest path of edges between two or more selection points (vertices or UVs). The Select Shortest Edge Path Tool determines the most direct path between any two selection points and selects the edges in between. The Select Shortest Edge Path Tool is particularly well suited to selecting a long and possibly winding path of edges on a mesh when you need to subsequently perform a Cut UV Edges operation.

Select > Convert Selection to Faces, Edges, Vertices, UVs Selects the component type connected to the current selection. For example, if you have faces selected and choose Convert to UVs, Maya will select all UVs connected to the selected faces.

Tool menu The items in this menu are also available from the toolbar.


Tool > UV Lattice Tool Manipulates the layout of UVs as a group by letting you create a lattice around the UVs for deformation purposes.

Lattice Settings Columns Specifies the number of columns for the current lattice manipulator. The minimum number of columns is 3 and maximum number is 8. Rows Specifies the number of rows for the current lattice manipulator. The minimum number of rows is 3 and the maximum number is 8. Falloff Specifies the lattice manipulator's level of influence or falloff value. Use Bounding Rectangle When on, the current lattice manipulator cannot extend past the outer edge or boundary of the target geometry.

Snap Settings The lattice snap settings are relative to each UV affected by the lattice. Pixel Snap (Image > Pixel Snap) needs to be on in the UV Texture Editor for the UV Lattice Tool Snap Settings to have any effect.

Placement Select where control points snap to. Snap Corner When on, the UV lattice deformer’s control points snap to the corners of each UV. Snap Center When on, the UV lattice deformer’s control points snap to the centers of each UV.


Tool > UV Smudge Tool Moves the position of selected UVs and their neighboring UVs to a diminishing extent that is user defined.

Smudge Settings Effect Type Select the way the UVs follow the brush tool. Fixed Moves the selected UVs in the direction of the UV Smudge Tool brush’s movements. UVs appear to follow or move with the brush. This setting moves UVs similar to the way the Soft Modification Tool moves vertices. Smudge Drags or smudges UVs in the direction of the UV Smudge Tool brush’s movements.

Falloff Type Select the way that the UV movement falls off as the brush moves. Exponential Moves UVs based on the distance they are from the UV Smudge Tool brush. A UV moves exponentially more the closer it is to the brush. Linear Moves UVs based on the distance they are from the UV Smudge Tool brush. A UV moves linearly more the closer it is to the brush. Constant Moves all UVs the same amount in the direction of the UV Smudge Tool brush’s movements. Smudge Size Sets the size of the UV Smudge Tool brush. In the UV Texture Editor’s view, you can also press b + drag to resize the Smudge Tool brush.


Pressure Sets the magnitude of the smudge and specifies how much the UV Smudge Tool brush affects the selected UVs. This is only available when the selected Effect Type is Smudge. Middle Mouse Initiates When on, middle-drag to smudge the layout of your UVs. When off, drag to smudge the layout of your UVs.

Tool > Move UV Shell Tool Lets you select and reposition a UV shell in the 2D view of the UV Texture Editor by selecting a single UV on the shell. You can automatically prevent the repositioned UV shell from overlapping other UV shells. See also UV Texture Editor toolbar on page 154. Prevent Overlap The Prevent Overlap setting restricts a UV shell from being accidentally moved to a position where it would overlap existing UV shells in the UV Texture Editor view. It is on by default. For example, if you select and move a UV shell and reposition it to an area that is already occupied by an existing UV shell, the selected shell will do one of the following: ■

Snap back to its previous location (when the overlap is large).

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Snap to the closest location possible based on the direction you dragged the UV shell (when the overlap is small). Shell Spacing Specifies the distance the repositioned UV shell will be separated from other existing UV shells as a percentage of the map size when Prevent overlap is turned on. Placement iterations Specifies the number of times the tool checks between the start and end positions when translating one or more UV shells in order to optimally achieve the Shell Spacing distance without snapping back to the original location. A higher number produces the closest result possible, but takes longer to complete the move. The number of selected UV shells also affects the time to complete the move. The default setting is 16.

Tool > Smooth UV Tool Let’s you interactively unfold or relax UVs. To use this tool, you must first select a set of UVs. Then, you can adjust the unfold or relax of the UVs by the respective control to the right. For more information, see Relax and untangle UVs on page 63 or Unfold a UV mesh on page 65.


Pin Borders When on, the border UVs of the selected UV set will not move when the Unfold or Relax controls are moved. Space Allows you to adjust whether you Unfold or Relax the UVs in UV space or World space.

Image menu For more information on using the features in this menu see Display a texture behind the UVs on page 42.

Image > Display Image Shows or hides the texture image. This item can also be found in the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Image > Dim Image Reduces the brightness of the currently displayed background image. Dimming the background image lets you more easily view and select components in the UV Texture Editor’s view. Selecting the item toggles it on or off depending on its current state.

Image > Display Unfiltered Turns off pixel blurring to show exact pixel boundaries. This item can also be found in the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Image > Shade UVs Shades active UV shells in a semitransparent way. Using Shade UVs you can: ■

Display areas where UVs and UV shells overlap within the 2D view of the UV Texture Editor. Regions where UVs and UV shells overlap are shaded with more opacity when compared to the default shading. See also Display overlapping UVs on page 54.

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Displays the UV winding order for UV shells as they appear within the 2D view of the UV Texture Editor. UV shells that are front facing (that is have a clockwise winding order), are shaded blue. UV shells that are back facing


(that is have a counterclockwise winding order), are shaded red. See also Display UV winding order on page 55. Front facing color Specifies the shaded color for UV shells with a clockwise winding order. The default color is blue. Front facing alpha Specifies the transparency value for the front-facing shaded UV shells. A value of 0 is fully transparent while a value of 1 is fully opaque. The default is 0.25. Back facing color Specifies the shaded color for UV shells with a counterclockwise winding order. The default color is red. Back facing alpha Specifies the transparency value for the back-facing shaded UV shells. A value of 0 is fully transparent while a value of 1 is fully opaque. The default is 0.25.

Image > Display RGB Channels, Display Alpha Channel Switch between displaying the texture image and its alpha (transparency) channel. These items can also be found in the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Image > Pixel Snap Determines whether or not to automatically snap UVs to pixels. Snapping is to pixel corners or centers. This item can also be found in the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Placement Select where Pixels snap to. Snap Corner When on, the selected UVs snap to the corners of other UVs. Snap to Center When on, the selected UVs snap to the centers of other UVs.

Image > Image Range Use these settings to change how much of the texture appears in the texture editor. Minimum U/V and Maximum U/V You can explicitly set the size of the image by setting these options, or you can select one of the presets.


Presets Select one of the preset image ranges and click Apply. None The texture space is defined by the Minimum and Maximum U and V values. Grid Size The texture fills the extent of the grid (defined in the Grid Options window). Unit Size The texture fills the 0 to 1 (or unit) texture space.

Image > Use Image Ratio Switches between showing square texture space and texture space with the same ratio of width to height as the image. This item can also be found in the UV Texture Editor toolbar for quick access. See UV Texture Editor toolbar on page 154.

Image > UV Texture Editor Baking Bakes the texture and stores it in memory. See also UV Texture Editor toolbar on page 154. Baked Texture Resolution The resolution used when baking the texture.

Image > Create PSD Network Creates an Adobe® Photoshop® texture you can use as a texture map. When this feature is used, a PSD layer of the UVs can be explicitly created to aid painting of the texture. For more information, see Use PSD Networks as textures in Maya and Create a PSD file with layer sets from within Maya in the Shading guide.

Image > Update PSD Networks When you modify a PSD file in Adobe® Photoshop® that is connected to a Maya PSD node, you can update (refresh) the image in Maya to show the modifications immediately. All PSD networks in the scene are updated. See Update PSD Networks in the Shading guide.

Textures menu Select which image texture to show in the UV Texture Editor. Select an image from the drop-down list that appears. If no texture images are assigned the list appears empty.


UV Sets menu Select the UV set you want to edit in the UV Texture Editor by selecting the name of the UV set from the drop-down list that appears. See UV sets on page 11.

UV Texture Editor toolbar

These are descriptions of the items in the UV Texture Editor toolbar. The UV Texture Editor toolbar lets you readily access many of the frequently used items that exist within the UV Texture Editor menus. For the features that have options, you can right-click a button to display its options.

UV Tool buttons UV Lattice Tool

Manipulates the layout of UVs as a group by letting you create a lattice around the UVs for deformation purposes. Shortcut for Tool > UV Lattice Tool in the UV Texture Editor menu.

Move UV Shell Tool

Lets you select and reposition a UV shell by selecting a single UV on the shell. You can automatically prevent the repositioned UV shell from overlapping other UV shells in the 2D view. Shortcut for Tool > Move UV Shell Tool in the UV Texture Editor menu.

UV Smudge Tool

Moves the position of selected UVs and their neighboring UVs to a diminishing extent that is user defined. Shortcut for Tool > UV Smudge Tool in the UV Texture Editor menu.


Select Shortest Edge Path Tool

Lets you select a path of edges between two vertices on a surface mesh. The Select Shortest Edge Path Tool determines the most direct path between any two selection points and selects the polygon edges in between.

Interactive Unfold/Relax Tool

Let’s you control the amount of unfold or relax applied to a selection of UVs by dragging the mouse across the screen.

UV orientation buttons These items let you edit the orientation and rotation of UVs. Flip U

Flips the positions of the selected UVs in the U direction. Shortcut for Edit UVs > Flip.

Flip V

Flips the positions of the selected UVs in the V direction. Shortcut for Edit UVs > Flip.

Rotate UVs counterclockwise

Rotates the positions of the selected UVs by 45 degrees in a counterclockwise direction. Shortcut for Edit UVs > Rotate.

Rotate UVs clockwise

Rotates the positions of the selected UVs by 45 degrees in a clockwise direction. Shortcut for Edit UVs > Rotate.

Cut and sew UV buttons These items let you cut and sew UV shells. Cut UVs along selection

Separates UVs along the selected edges, creating borders. Shortcut for Edit UVs > Cut UV Edges.

Split UVs

Separates UVs from each other along the edges connected to the selected UV points, creating borders. Shortcut for Edit UVs > Split UVs.

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Sew UVs

Attaches UVs along the selected borders, but does not move them together in the texture editor view. Shortcut for Edit UVs > Sew UV Edges.

Move and Sew UVs

Attaches UVs along the selected borders, and moves them together in the texture editor view. Shortcut for Edit UVs > Move and Sew UV Edges.

UV layout buttons Layout

Attempts to arrange the UVs into a cleaner layout, based on the settings in the Layout UVs option box. Shortcut for Edit UVs > Layout.

Grid UVs

Moves every selected UV to its nearest grid intersection in texture space. Shortcut for Edit UVs > Grid. To change the grid, right-click the View Grid button on the toolbar.

Unfold

Unwraps the selected UV mesh while attempting to ensure that the UVs do not overlap. Shortcut for Edit UVs > Unfold.

Relax

Spreads out the selected UV mesh to make it easier to work with. Shortcut for Edit UVs > Relax.

UV alignment buttons Align Min U

Aligns the positions of the selected UVs to the minimum U value. Shortcut for Edit UVs > Align.

Align Max U

Aligns the positions of the selected UVs to the maximum U value. Shortcut for Edit UVs > Align.


Align Min V

Aligns the positions of the selected UVs to the minimum V value. Shortcut for Edit UVs > Align.

Align Max V

Aligns the positions of the selected UVs to the maximum V value. Shortcut for Edit UVs > Align.

Isolate selection buttons These items let you work on a subset of UV faces while hiding the rest. Toggle Isolate Select Mode

Switches between showing all UVs and only the isolated UVs. Shortcut for View > Isolate Select > View Set.

Add selected to isolation

Adds the selected UVs to the isolated subset. When you click the Toggle isolation button the selected UVs will be visible. Shortcut for View > Isolate Select > Add Selected.

Remove selected from isolation

Removes the selected UVs from the isolated subset. Shortcut for View > Isolate Select > Remove Selected.

Remove all

Clears the isolated subset. You can then select a new set of UVs and click Toggle isolation to isolate them. Shortcut for View > Isolate Select > Remove All.

Image and texture buttons These items let you control the display of images and textures in the UV Texture Editor. Display Image

Shows or hides the texture image. Shortcut for Image > Display Image.


Toggle Filtered Image

Switches the background image between hardware texture filtering and sharply defined pixels. Shortcut for Image > Display Unfiltered.

Dim Image

Reduces the brightness of the currently displayed background image. Shortcut for Image > Dim Image.

View Grid

Shows or hides the grid. Shortcut for View > Grid.

Pixel Snap

Chooses whether to automatically snap UVs to pixel boundaries. Shortcut for Image > Pixel Snap.

Shade UVs

Shades selected UV shells in a semi-transparent fashion so you can determine areas of overlap or UV winding order.

Toggle Texture Borders

Toggles the display of texture borders on UV shells. Texture borders appear with a thick line.

Display RGB Channels

Displays the RGB (color) channels of the selected texture image. Shortcut for Image > Display RGB Channels.

Display Alpha Channel

Displays the Alpha (transparency) channel of the selected texture image. Shortcut for Image > Display Alpha Channels.

UV texturing buttons UV Texture Editor Baking

Bakes the texture and stores it in memory. See Image > Dim Image on page 151. Shortcut for Image > UV Texture Editor Baking.


Update PSD Networks

Refreshes the PSD textures currently in use for the scene. When you modify a PSD file (in Photoshop) that is connected to a Maya PSD node (in Maya), you can update (refresh) the image in Maya to show the modifications immediately. See Image > Update PSD Networks.

Force editor texture rebake

Rebakes the texture. If you turn on Image > UV Texture Editor Baking, you must rebake the texture (using Force Editor Texture Rebake) after making changes to the texture (File node and place2dTexture node attributes) in order to see the effect of those changes.

Use Image Ratio

Switches between showing square texture space and texture space with the same ratio of width to height as the image. Shortcut for Image > Use Image Ratio.

UV edit buttons U coordinate, V coordinate

Shows the coordinates of the selected UVs. Edit the text boxes and press Enter to move the points.

Refresh UV values

The UV coordinates in the text boxes on the toolbar do not update automatically as you move the selected UV point. Click the refresh button to update the values in the text boxes.

UV Transformation Entry

Changes the UV coordinate entry mode between absolute and relative values. Also provides entry of UV rotation values.


Copy

Copies the selected UV points or faces (depending on the Copy/paste faces or UVs button) to the clipboard.

Paste

Pastes UV points or faces (depending on the Copy/paste faces or UVs button) from the clipboard.

Paste U to selected UVs

Pastes only the U values on the clipboard onto the selected UV points.

Paste V to selected UVs

Pastes only the V values on the clipboard onto the selected UV points.

Copy/paste faces or UVs

Switches the Copy and Paste buttons on the toolbar between working on UVs and UV faces.

Cycle UVs

Rotates the U and V values of the selected polygon.

UV Set Editor Create UVs > UV Set Editor The UV Set Editor lets you create and edit UV sets for multiple polygon meshes simultaneously. The UV Set Editor lists only the UV sets for the currently selected polygon meshes. You must first select the polygon meshes in order to edit the UV sets. New Creates a new, empty UV set on the currently selected objects. You can then create the UVs in the set using one of the mapping/projection methods. This feature is the same as Create UVs > Create Empty UV Set. Rename Lets you rename the currently selected UV set.


Delete Deletes the currently selected UV set. This feature is the same as Create UVs > Delete Current UV Set. Copy Creates a new UV set based on an existing UV layout or transfers a UV layout from one set to another. This feature is the same as Copy UVs to UV Set. Propagate Assigns the selected UV set from the UV Set Editor list to the selected objects in the scene. The selected UV set becomes the active UV set for those objects. Unmapped Selects unmapped faces on any selected objects in the scene. This aids in visually determining any areas where texture maps do not appear or appear incorrectly.

UV Set Editor | 161

162

UVs tool reference

7

Move tool (in UV texture editor) The Move tool has different options when you work in the UV texture editor panel. Retain Component Spacing When this option is off, if you snap to a point (with grid snapping, point snapping, or pixel snapping), all selected UVs snap to the same point, bunching them up. When this option is on, if you snap to a point, the selected UVs keep their positions relative to each other.

163

164

Index A Add selected to isolation (UV tool button) 157 Adobe Photoshop texture, using as texture map 153 align UVs 114 tool buttons 156 alpha channel adjust for UV shells 151 display 152 include (Warp image option) 116 artwork, mapping onto character 4 aspect ratio, preserve when normalizing UVs 111 assign shader to projection 28 attaching UV shells 52 automatic UV mapping 22 options 102 projection manipulator 23 separating, merging, attaching UV shells 52 user-defined projection 25

B backdrop image, arranging UVs to 42 Background color (Warp image option) 116 background image, dimming 151 Background mode (Warp image option) 115 baking per-instance UV sets 91 UV texture 153 Best plane (Planar Mapping option) 97 Best Plane Texturing Tool 107 Bilinear Filtering (Warp image option) 116 borders (see UV borders) 122 boundaries (see UV borders) 63

Bounding box (Planar Mapping option) 97

C camera view, use as planar projection 106 circle mapping UV border to 118 mapping UVs to 60 Clipboard Actions Mesh menu 80 Collectively (Normalize UVs option) 110 colors adding for UV shells 151 copying between polygons 80 UV sets for 13 components UVs, selecting 32 confirming UV placement 28 Constrain UVs (Unfold option) 125 converting UV selection 33 Copy (UV tool button) 160 Copy UVs to UV Set 84, 108 Copy/paste faces or UVs (UV tool button) 160 Create Empty UV Set 83, 107 Create PSD Network (UV Texture Editor) 153 Create UVs Based On Camera 106 creating per-instance UV sets 90 Cut UV Edges 134 Cut UV Edges (Edit UVs menu) 134 Cut UVs along selection (UV tool button) 155 Cycle UVs (UV tool button) 160 Cylindrical Mapping 99 cylindrical UV mapping 19 options 99

165 | Index

D decal sheet, UV mapping 4 Delete Current UV Set 84, 109 Delete UVs 43, 137 deleting UVs 137 Dim Image (UV tool button) 158 Display Alpha Channel (UV tool button) 158 Display Image (UV tool button) 157 Display RGB Channels (UV tool button) 158 displaying UVs 31 distortion of texture maps, minimize with Unfold 65

Flip UVs 111 flipping reversed UV shells (Layout option) 131 selected UV shells 111 UV faces 36 UV shells 79 UV tool buttons 155

G grid in UV Texture Editor 47 reposition UVs to 114 UV tool button 156 Grid UVs 114

E

H

edge path, selecting shortest 147 edges (see UV borders) 122 Edit NURBS UV mode 93 examples brick wall with spray paint on top 12 mapping artwork on games character 4 UVs needing editing 4 warp image applications 45 weight solver while unfolding UVs 126

history, keep (Unfold option)

F faces selecting 147 selecting from UV components 33 showing those inside selected UVs or edges 35 falloff UV Smudge tool 149 file format Warp image option 116

166 | Index

126

I Image menu UV Texture Editor 151 Image Range (UV Texture Editor) 152 image ratio change in UV Texture Editor 153 images assigned, viewing UVs with 34 background, dimming 151 creating by comparing UV sets 115 keeping width/height ratio (Planar Mapping option) 98 minimizing distortion with Unfold 65 tile (Warp image option) 117 using to arrange UVs 42 warping 45 Interactive Unfold/Relax Tool (UV Texture Editor) tool button 155 isolating UVs 33

L lattice tool for UVs 49 options 148 layered texture, UV sets 13 Layout UVs 129 layout of UVs (see UV layout) 129 light baking 11 lighting information in UV sets 11 limitations per-instance UV sets 93

M manipulator projection, for automatic mapping 23 Map UV Border 61, 117 mapping UVs 6 to a square or circle 60 marking menus UV Texture Editor 10 Merge UVs 136 Merge UVs (Edit UVs menu) 136 merging UV shells 52 meshes (see surface meshes) 29 Move and Sew UV Edges 135 Move and Sew UVs (UV tool button) 156 Move UV Shell Tool (UV Texture Editor) 150 tool button 154 moving UVs 35 multi-texturing with multiple UV layouts 11

N New Image Name (Warp Image option) 115 non-manifold geometry merging polygons 136 Normalize 110

normalize UVs 110 NURBS surfaces assigning textures 2 editing UV texture coordinates

93

O objects, defining for UV projection orientation of UVs, buttons 155 overlapping UV shells 6 UVs 5 UVs, viewing 54 Overwrite existing file (Warp image option) 116

26

P Paste (UV tool buttons) 160 Per Instance Shared 87 Per Instance Unshared 87 per-instance UV sets 87 baking 91 creating 90 example 88 limitations 93 Percentage Space (Automatic mapping option) 106 perspective view displaying with UV Texture Editor 9 Photoshop texture, using as texture map 153 pinning UVs on border 63 Relax option 121 Unfold option 124 Pixel Snap (UV tool button) 158 pixels blurring, turning off 151 snap UVs to 152 switching between blended and sharp-edged 42 Planar Mapping 97 planar UV mapping 15 planes creating from vertices for projection 107

Index | 167

defining for projected UV mapping 25 mapping UVs 15 polygon meshes techniques for UV mapping 3 transfer UVs between 29 unfold 65 unfold and relax example 73 unfold setup 66 polygons assigning textures 2 copying UVs, colors, shaders between 80 surface meshes, creating UVs 3 tasks in UV Texture Editor 10 Polygons menu (UV Texture Editor) 140 Delete UVs 44 Unfold 65 pre-lighting surfaces 11 projecting UVs assign shader 107 automatically from multiple planes 22 criteria for user-defined objects 26 cylindrical 19 defining planes 25 from specified plane 107 insert before deformers (Automatic mapping option) 103 insert before deformers (Cylindrical mapping option) 99 insert before deformers (Image Mapping option) 98 planar (one plane) 15 spherical 21 use camera view 106 projection manipulator Best plane option 97 Bounding box option 97 manually adjusting 98

R rectangle place around UVs (lattice) 148 Refresh UV values (UV tool button) 159

168 | Index

Relax UVs 63 Relax (Edit UVs menu) 121 description 63 untangling UVs first 117 UV tool button 156 Rename Current UV Set 84, 109 resolution warp image options 116 reversing UV shell 79 UV wounds 79 RGB channels, display 152 Rotate UVs 113 UVs diescreetly 37 Rotate UVs (UV tool buttons) 155 rotating UV shells 79 UV shells for best fit (Layout option) 132 UVs, description 35 UVs, tool buttons 113

S Scale mode automatic mapping option 104 scaling UVs 35 scene view selecting UVs 32 Select menu (UV Texture Editor) 33, 147 Select Shortest Edge Path Tool (UV Texture Editor) 147 tool button 155 selection converting to faces, edges, vertices, UVs 147 UVs, UV components, UV shells 32 semitransparent display of UVs 54 separating UV shells 52 Set Current UV Set 108 Sew UV Edges 135 UV tool button 156

Shade UVs 54 description 54 using¶ 55 UV tool button 158 UV winding order 55 shaders assign to projection 107 copying between polygons 80 shading storing information in UV sets 11 sharing UV sets 87 Shell stacking (Automatic mapping option) 105 shells (see UV shells) 6 shortest edge path, selecting 147 smudge tool (UVs) 51 settings 149 snap UVs to grid 47 snapping UVs 38 Source image name (Warp Image option) 115 spacing between UV shells 7 Spacing presets Automatic Mapping option 105 Layout option 133 Spherical Mapping 100 spherical UV mapping 21 options 100 Split UVs 135 Split UVs (Edit UVs menu) 135 tool button 155 square mapping UV border to 117 mapping UVs to 60 stacking UV shells (Layout option) 132 Straighten UV Border 63, 120 straightening border UVs 62 options 120 subdivision surfaces assigning textures 2 editing 145 exporting image of UVs 48 tasks in UV Texture Editor 10

Subdivs menu (UV Texture Editor) 145 UV Snapshot 48 subset of UVs, displaying 33 surface meshes creating UVs for 2 NURBs 2 polygons 2 subdivision surfaces 2 techniques for UV mapping 3 surfaces pre-lighting 11

T texture coordinates (see UVs) 1 texture image modify using UV sets 115 texture maps 1 distorted 5 for surface types 2 minimize distortion with Unfold 65 placement on 3D surfaces 1 use Adobe Photoshop texture 153 texture space, UV 1 textures assigning to a UV set 85 flipping 36 repeating with UV range 6 thicken borders 41 Textures menu (UV Texture Editor) 153 Tiled (Warp image option) 117 Toggle Filtered Image (UV tool button) 158 Toggle Isolate Select Mode (UV tool button) 157 Toggle Texture Borders button (UV Texture Editor button) 41 tool buttons, UV Texture Editor 154 Tool menu UV Texture Editor 147 transparency UV sets for 13

U U coordinate (UV tool button)

159

Index | 169

Unfold UVs 123 Unfold UVs 65 unfolding 65 description 65 polygon UV texture mesh 70 preparing 68 tips 70 tool button 156 UV mesh 123 Unitize UVs 111 unitizing UVs 111 untangling UVs at borders 117 before mapping 60 interior 63 unwrapping UV meshes with minimal distortion 65 Update PSD Networks (UV tool button) 159 Use Image Ratio (UV tool button) 159 user-defined UV mapping 25 criteria for projection objects 26 UV borders creating by splitting along selected UVs 135 creating by splitting UV edges 134 moving and sewing together 135 pinning to untangle interior 63 pinning UVs on (Relax option) 121 pinning UVs on (Unfold option) 124 positioning 117 selecting 147 sewing 135 straightening 62 straightening, options 120 unitizing 111 untangling 60 weighting 122 UV components selecting 32 UV Lattice Tool 49 description 148

170 | Index

tool button 154 UV layout modify 49 options 129 UV shells 58 UV tool button 156 UV mapping automatic (for best placement) 22 cylindrical 19 definition 2 planar 15 production workflow 4 spherical 21 user-defined 25 UV meshes 4 reassembling 5 transfer UVs between 29 unfold and relax example 73 unfold setup 66 unfolding 65 unwrapping 123 unwrapping with minimal distortion 65 UV sets 11 assigning textures to 85 compare to produce image 115 comparing to create warp image 45 copying UVs to another 86 creating 83 deleting 84 deleting current 109 duplicating 84 empty, creating 107 for a layered texture 13 for color and transparency 13 menu (UV Texture Editor) 154 overview 11 per-instance 87 polygon mesh, specifying for 108 renaming 84 renaming current 109 sharing 87 source and destination, warp image options 116 storing shading and lighting information 11

switching between 84 UV shells 6 automatic mapping 23 avoid overlapping 6 changing orientation 79 components, selecting 32 exporting image of 48 flipping 111 flipping reversed (Layout option) 131 laying out automatically 58 layout options 104 merge together 136 moving 36, 150 positioning UVs on border 117 rearrange layout 129 scaling options (automatic mapping) 104 scaling, stretching, flipping, arranging 58 selecting 147 selecting from UV components 33 selecting UVs 32 separating (Layout option) 131 separating, merging and attaching 52 shading 151 spacing between 7 spacing presets option 105 stacking options 105 straightening border UVs 62 untangling border UVs 60 untangling interior UVs 63 UV Smudge Tool 51 description 149 tool button 154 UV Snapshot 48 description 48 options 144 Subdivs menu 48 UV Texture Editor 8 adjust size of image 152 Align UV buttons 156 baking 153 Baking (UV tool button) 158 changing UV shell orientation 79

copying UVs from one UV set to another 86 Create PSD Network 153 displaying a subset of UVs 33 displaying with perspective view 9 dollying and tracking 41 editing UV texture coordinates (NURBS) 93 grid 6, 47 Image menu 151 marking menus 10 menu items 140 overview 8 Polygons menu 140 Select menu 33, 147 selecting UVs 32 separate menus for UV tasks 10 Shade UVs 55 smudge UV layout 51 Subdivs menu 145 switching between UV sets 84 Textures menu 153 thicken texture borders 41 tool buttons 154 Tool menu 147 toolbar options 154 using image to arrange UVs 42 UV Lattice Tool 49 UV Sets menu 154 UV snapshot of subdivision surfaces 48 View menu 145 viewing items 10 viewing overlapping UVs 54 viewing UVs 31 Warp Image 45 UV tool buttons, UV Texture Editor 154 UV Transformation Entry (UV tool button) 159 UVs 1 aligning 114 aligning to grid 114 aligning, buttons 156 arranging 6 arranging using an image backdrop 42

Index | 171

automatic mapping 22 best placement 22 confirming placement 28 constrain (Unfold option) 125 converting selection 33 copying between polygons 80 copying to new UV set 108 creating 3 definition 1 deleting 43 discrete rotate and scale 37 displaying 2D texture coordinates with 3D scene view 9 displaying a subset 33 displaying if texture image assigned 34 distorted projection 5 editing for NURBS surfaces 93 evaluating 4 image of shell layout 48 lattice, placing around 148 layout of shells 58 mapping techniques 3 mapping tips 6 menu reference 97 moving, rotating, scaling 35 multiple layouts 11 normalizing 110 orientation, changing 155 overlapped, viewing 54 overlapped, why not desirable 5 overlapping shells 6 overview 1 pin (Unfold option) 124 positioning on border of UV shell 117 repeating texture 6 rotating 113 selecting components 32 separating, merging and attaching shells 52 sets, creating 83 sewing along edges 135 smudge layout 51

172 | Index

snapping 38 snapping example 38 snapping to grid 47 snapping to pixels 152 splitting along edges 134 splitting along selected path 135 straightening borders 62 tasks in UV Texture Editor 10 tips 4 transferring between meshes 29 unitizing 111 untangling at borders 60 untangling interior 63 viewing in UV Texture Editor 31 winding order 55 zooming in or out to see 41

V V coordinate (UV tool button) 159 vertices, create projection plane from 107 View Grid (UV tool button) 158 View menu (UV Texture Editor) 145 viewing UVs 31

W warp image 45 applications 45 description 45 options 115 Warp Image UVs 45, 115 weight solver Unfold UVs 123 workflow example 126 winding order of UVs 55

Z zooming to show all UVs

41

MappingUVs

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