V-Ray for Rhino 1.0
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Table of Contents 01. Installing V-Ray for Rhino1.0 ........................................................................... 004 02. Activating V-Ray for Rhino 1.0 ......................................................................... 005 03. V-Ray for Rhino Toolbar ................................................................................
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Open V-Ray for Rhino Toolbar
04. ? ? ? ? ? V-Ray for Rhino? ? ? ? ...................................................................
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05. V-Ray for Rhino Render Options .....................................................................
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Open V-Ray for Rhino Render Options Load and Save Render Options
06. V-Ray for Rhino Material Editor ......................................................................
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V-Ray Material Editor Diffuse How to add new material How to duplicate a material How to change the name of a material How to remove material Others
016 07. Use Material ................................................................................................. 08. Add Lights ..................................................................................................018 09. The Characteristics of Rectangular Light .............................................................021 Size does matter Shadow changes according to the size Impacts on reflective objects due to Visible and Invisible Rectangular Light Double Sided Option
10. Material: Reflection Material ...........................................................................024 Adding Reflection layer Fresnel Reflections Explained
11. Reflection and Highlight ................................................................................ 026 12. Other characteristics of reflectivity ..................................................................027 Reflection Glossiness Reflection Filter
13. Material: Transparent Material ........................................................................
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Add transparent layer Transparency percentage of material The color of transparent material Fog Settings Explained The Refraction of transparent material The Glossiness of transparent material The shadow of transparent material Double-sided material
14. Material: Transparent Material .......................................................................
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Add Emissive Layer Adjust the Intensity Adjust the Color Texture Editor Setting
15. Material: Texture Mapping ..... ........................................................................ 041
Texture Mapping UI types and adjustment
16. Material: Bump Map ......................................................................................
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Add Bump map
17. Material: Transparency Mapping ......................................................................
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What's Transparency Mapping? The logic of Transparency map Another way of using Transparency map Other uses of transparency
18. Illumination: Environmental Lighting ................................................................
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Let's do a test first Interior or Exterior? Techniques to adjust the Brightness HDR Environment light Bitmap Environment light source Environment light source for semi-open space Issue of irradiant light
19. Render Engine ............................................................................................
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Primary Engine Secondary Engine Primary Engine: Irradiance Map Primary Engine: Quasi Monte-Carlo Secondary Engine: Light Cache
20. Depth of Field .............................................................................................
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What is Depth of Field? How to find out the current setting of focus distance of the camera? Size of Aperture Change Focal Distance
21. Caustic Effect .............................................................................................
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What are Caustics? Brightness
22. Liquid inside of transparent Glass .................................................................... 072 Strange Effects
23. Adjusting the Camera ....................................................................................073 Rotate the camera Adjusting the lens
24. Lighting Dialog Box .......................................................................................
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25. Color Mapping ............................................................................................
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The Function of Color Mapping Types of Color Mapping
26. Adaptive Subdivisions Control ..........................................................................077 Adaptive Subdivisions Sampler Fixed Rate Sampler Adaptive QMC Sampler
27. Resolution of an Image ....................................................................................078 Image size setting File saving set up
28. V-Ray frame Buffer ....................................................................................... Render image window tool box
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Installing V-Ray for Rhino 1.0
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1.Make sure Rhino is not running then install VRayforRhino3_1.0.exe from the CD
2.License Agreement, click next to continue
3. Choose complete setup type, click next
4.Click install to begin installation
5.
6.Installation complete
Installing
V-Ray for Rhino 1.0
Activating V-Ray for Rhino 1.0 1. After finishing the installation, run the Rhino program. Click Render on the tool bar to choose the Current Renderer as V-Ray for
3.If you already have a serial number, you can select the other option, “I have a serial number and I want to activate V-Ray for
5. Activating usually takes several seconds to finish
2.The InstallShield Wizard will ask you to select one of the options. If you haven't purchased V-Ray for Rhino, you can choose “I want to evaluate V-Ray for Rhino, but I do not want to activate at this time
4. Enter your serial number then click next. It will start activating
6.The activation for V-Ray for Rhino is now complete. You will not need to activate it
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V-Ray for Rhino Toolbar Open V-Ray for Rhino Toolbar V - R a y f o r R h i n o ' s To o l b a r w i l l n o t o p e n a u t o m a t i c a l l y. U s e r m u s t o p e n a n d i n s e r t it onto the screen. Use Tools>Toolbar Layout, click File>Open…, under C:\Program Files\Rhinoceros 3.0\Plugins\Vrayforrhino\Misc, find VRayforRhino.tb and insert it
1. From Toolbar Layout window, select Open under File
3. Select VRay for Rhino and close the window
2. Find Vrayforrhino.tb and open it
4. This is what you will see after you insert the toolbar
V-Ray for Rhino toolbar consists of three major tools. They are VRay Materials, VRay Options and Show VRay Frame Buffer. You can also find them from the tab above
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? ? ? ? ? V-Ray for Rhino? ? ? ?
以上HDR以及著色圖片由Dosch
Design公司授權提供給本手冊使用 http://www.doschdesign.com
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V-Ray for Rhino Render Options Open V-Ray for Rhino - - Render Options The V-Ray for Rhino Options controls all parameters for V-Ray. You can open this Render Options from the menu bar above or click directly on the V-Ray Options from the toolbar
Save and load Option settings There are many Options settings in V-Ray for Rhino. Users can save their preferred settings, or save different files according to different scenes, different render quality setting, or different GI engines. Use File>Save to save Options settings. It will be saved as .visopt file format. You can save any Options scheme so that they can be loaded to another scene later. Also, when you save your Rhino file all changes in V-Ray Options setting will also be saved. Use File>Load to load saved .visopt Options files. It will then replace the current setting. Use Restore Defaults to restore all settings in Options.
Open “Cups-Original.3dm”. There are 3 cups and a ground plane in the file. None of the objects have any materials assigned to them and there is no light in the scene. Click the blue render icon and you will get this gray tone image without changing any setting in the V-Ray Options.
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Open V-Ray Options window and pull down the Global Switches, Environment and Indirect Illumination tabs as 1. Global Switches： Uncheck Hidden Lights and Default Lights under the Lighting section. Hidden Lights refers to any lights that are either hidden or on a hidden layer. By unchecking the Hidden Lights box, those hidden lights will be disregarded by V-Ray. To prevent any hidden lights from affecting the final render output, we recommend you uncheck the Hidden Lights. Default Lights are the lights that Rhino uses to illuminate the model within the viewport. Users can not see or edit these lights from the scene. If one uncheck the Default Lights and does not check the GI below, the render will turn out totally black. 2. Indirect Illumination： Check the On under the GI section. That turns the Indirect Illumination on, also called the Global Illumination. We will explain those green dot items more later. 3. Environment： Check the boxes before GI and Background.
These settings controls the appearance and brightness of the Environment, and therefore, the main illumination of the scene. Please adjust those three items then render. You will get the image with Global Illumination. Compare to the image without Global Illumination, you can see the objects don't have dark shadow because the whole environment is now providing the illumination for the scene.
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The image has a blue tone is because the default environment color of V-Ray is set in light blue(RGB 204, 224, 225). Please click the color box under GI to edit the color. Change the Sat from 51 to 5. The color is changed to be almost white(RGB 250, 252, 255). Click OK to accept the changes and then click Render. The image color becomes very close to white like the image on the right.
By default objects which have not been assigned materials receive Rhino’s standard white material. To assign materials to an object and make adjustments, we need to open the Properties tab Two ways to assign materials in V-Ray 1 . Press Ctrl+A to select all the objects in the scene then click the Object under the Properties window to select material. The objects are assigned materials by layers by default. Click Plug-in, there will show three tabs: Browse, Edit and Create.
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2. Click the Browse button, in the choose material window, select Default_VRay_Material, then click apply
3. Now the objects are applied with materials, so the Edit button is selectable. You can click on the Edit button to open the Material Editor to modify the materials
Another way to assign materials is through material editor. Please refer to page 13
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Material Editor in V-Ray for Rhino Material editor can be pulled out from the icon under VRay for Rhino tool box, from Material Editor from V-Ray tab, or by clicking the Edit button in Properties window.
V-Ray Material Editor V-Ray for Rhino's Material Editor has three parts: A . Material Workspace shows all the scene materials. Right clicking on different elements in the workspace will provide added functions within the Material Editor. B . Material Preview, the Update Preview button allows you to preview the adjusted materials. C . Options for material control. This is where parameters for each material is modified.
Click the Update preview button to update the preview image of the selected material. This preview is not updated in real time, therefore, it must be manually updated.
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Diffuse: Color：used to apply color on material. The m box on the right is used to apply a texture map to an object Transparency: used to adjust the color transparency. Black is opaque. White is transparent.
How to add new material: 1. Right click on Scene Material, select Add new material. 2 . Right click on Scene Material, select Import new material to import a saved material file. 3 . In the Properties window, click on Create button to add a new material
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How to duplicate a material Under Material Workplace, right click on the material you wish to duplicate, and select Duplicate. This is another way to add a new material
How to change the name of a material: Right click on the name of the material you wish to change, and select Rename. The name of the material can not have space or numbers in the first digit.
How to remove material: Right click on the name of the material you wish to delete, and select remove. If the material being removed is applied to the objects in the scene, V-Ray will show a pop-up window to ensure that you want to remove it.
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Others: Right click on the material you wish to export, and select export to export this material. The file format is .vismat, the file is 1 KB. This file can be imported or sent to other users later on By Right-Clicking on a Material you can also: 1 . Select Objects by materials: select the objects in the scene with this material 2 . Apply materials to object(s): Apply this material to selected objects in the scene. 3 . Apply materials to layer(s): Apply this material to selected layers. All the objects in the same layer will be applied with this material
Any materials under the Scene Materials can be applied to objects by clicking Browse under Properties.
Purge unused materials: Right click on Scene Materials to select purge unused materials to remove materials which are not applied on the scene objects.
Rhino’s Undo does not affect V-Ray for Rhino Options or Material Changes
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Use Material 01 . Open Cups - GI.3dm
Select all the objects. Under the Properties window, select material,
check plug-in and click Create to add a new material. Material Editor will show a new material named DefaultMaterial under Scene Material. 02 . Rename this new material as Ground
The file has already set GI environment light and background color. Hidden Lights and Default Lights are off. Other options are kept at their default settings.
03 . Select Diffuse to enter color selections .V-Ray's default color is R-127, G127, B127. Change the color to light gray as: R230, G230, B230 then exit 04 . Right click on Ground material. Select Duplicate and rename as Cup-Yellow.
05 .Deselect the ground plane by holding CTRL and clicking on it.
Then go back to Material Editor
and right click on Cup_Yellow and select Apply material to objects
V-R ay auto mati cally update s th e changes of mate ri als to th e obje cts. It is not necessa ry to apply mate ri als again.
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06 . Click on Diffuse and change the color to R255, G191, B0 (yellow) and exit 07 .Render and see if you get the same result like the image on the right.
08 . Duplicate the Cup_Yellow material and rename it as Cup_Green. Repeat 06 and set the value to R127, G255, B178 and exit. 09 . Apply this Cup_Green material to the bottom right cup 10 . Duplicate the Cup_Green and rename it as Cup_Orange. Repeat 06 again and set the value to R255, G94, and B0 this time. 11 . Select the cup on top and apply the Cup_Orange material to it.
13. Create a new material and name it Cup_White. Change the diffuse color to white. Select all of the objects on the layer named 12. Render and see if you can get the same
Inner Cup and apply the material to those
result as the image below.
objects
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Add Lights We didn't add any lights to the scene, however, the render turned out pretty good already. The shadow is kind of smooth because we used GI as the only light source. So we still need to add more lights in order to have more depth to the image 01 . Right click and hold on the Spot Light icon from toolbar above. A secondary toolbar will pop out, select the fourth one from the left (Create Rectangular Light)
02.From Top view, follow the steps below to
03. Start from bottom left and make your
create Rectangular Light in the scene
second left click to the bottom right of the scene.
04. To complete creating the light, make your
05 Select this Rectangular light you just
third left click on the top left of the scene,
created.
approximately the same distance as between first and second spots.
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06.Go to the Front view. Left click and hold
07. Render it and you will get a very bright
right on top of the light and drag it to the top,
image like the one below. That's because the V-
approximately 5X of the height of the cup
Ray's default setting of the Rectangular Light is set to No Decay. Please follow the steps below to adjust it
09. Uncheck the No Decay. This will make the distance between the light and objects being considered while rendering. That means the object further away from the light will recieve less light and become darker. To make the object brighter, you can either increase the intensity of the light or move the light closer to the object 08. Select the Rectangular Light. Under the Properties, click on Object and select Light.
11. Hit Render again and you will get a 10. When we uncheck
much better result like the image below
No Decay, the default setting
of
the
intensity is set to 1. Please change the Multiplier from 1 to 4.
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Please see the images below for comparison of different intensities.
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The Characteristics of the Rectangular Light The Rectangular Light plays a very important role in V-Ray. Despite its ease of use, it also produces a smoother final result. Unlike the Spot Light, Rectangular Light doesn't have the worry about the angle of the light. Rectangular light also allows reflective material to bounce the light around the scene because light is emitted from an area which has many points, as opposed to other lights which only emit light from a single point. Below are some important characteristics about Rectangular Light. Size does matter See images below and you will find the size of the Rectangular Light does affect its intensity.
Shadow changes according to size Larger Rectangular light spreads light to a larger area, so the shadow is not as clear as you will get from a smaller rectangular light. Compare the images below and you will see the differences between two different light sizes. The one on the left is rendered with a smaller light. If you want to have a stronger shadow, we do not recommend creating a small, high intensity light. It is better to use a different light type.
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Impacts on reflective objects due to Visible and Invisible Rectangular Light There is an Invisible option in Rectangular Light. It allows you to determine whether the light will be visible or invisible in the image. See images below. The one on the left has the Invisible option unchecked so the light appeared in the image. When a reflective material is applied to the object, the light will also be in the object’s reflections. The image on the right has the Invisible option checked. Thus, you don't see the light in the image or on the object with reflective material applied to it The default setting for Rectangular Light has the Invisible option unchecked. If you see any unusual dark shadow in your rendered image, please check if your camera is blocked by the Rectangular
1 You can tell the direction of the light from the short line on one side of the Rectangular Light. Rotate the light and you can change the direction of the light. The Double Sided option can turn the light direction from one side to both side of the light. Just like creating two lights with opposite directions. Move the light away from the floor or wall to avoid any black out area. The Double Sided option usually used when rendering a large interior scene. It helps to light the space without using a lot of lights. There will be more discussion about lighting and environments later on. The default has the Double Sided option unchecked. Of course, if you check the Invisible option, you will not see the light in those three images on the next page.
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1. Light direction towards the left side
2. Light direction towards the right side
3. When Double Sided option is checked
Pay attention to the size, location and intensity of the light because it will affect the brightness and shadow clarity of your final result. If the light is placed too far and is not bright enough, you can either increase the intensity or size of the light. On the other hand, you can lower the intensity or reduce the size of the light if you place the light too close. You need to keep adjusting the size, location and the intensity of the rectangular light in order to get a good lighting result. Other kinds of light work the same way. Different shapes, colors and materials of the objects, and different light types will all affect the image, therefore, the quantity, size, and location of the light need to be changed according to different scene. To get a better result, we recommend you change only one value at a time to see how it turns out after rendering until you get the image you want.
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Materials: Reflection This section is about how to add and edit reflective properties of materials. Please click on the red cup in the scene. Click on Edit button under Material selections in propertieis Adding a Reflection layer 1 .Click on the “+” next to Cup_Orange under Scene Materials to pull out all the layers. Right click on Reflection Layer. Select “Add new layer “to add a new reflection layer for this material. There will show Reflection under the material control section, as it shows on the right.
2. To remove a layer, right click on the layer you wish to remove then select remove
3. Click on Update Preview button to see the changes. The red ball becomes composed with blackand-white squares, which is because the default is set to be completely reflective. An object with this material works like a mirror that reflects the other object next to it. This kind of reflection is usually applied to mirror or metal, such as smooth stainless steel.
4. Click on the “m” next to the reflection color to add a reflection map.
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5. Scroll down the box next to Type, and then select Fresnel. Fresnel IOR is to control the angle at which surfaces begin reflecting. Keep the value at the default level of 1.55, then click Apply.
6. Click on the Update Preview again The Material now has reflection quality with the same color on it. Notice the “m” on the right side of the Reflection is now changed to “M”. That means there is a Map applied to that parameter
7.Below image rendered with Fresnel IOR set to 2.5, it has more reflection and looks more like a metal texture now. The cup has some black reflection due to the default setting of the background color is black. Under V-Ray Option, change the 6. Please use the same method and apply
color under Environment>Background to
Fresnel to other colors and render it.
white and see what you will get
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Fresnel Reflections Explained Fresnel Reflection is a naturally occurring phenomenon that states that an object becomes more reflective the greater the angle at which it is seen(think of looking at a window from straight ahead as opposed to an angle). Through manipulating the Index of Refraction(IOR) the reflective characteristics of an object can be changed. A lower IOR means that a larger angle is needed between the observer and the object before the object begins reflecting. A higher IOR means that a smaller angle is need, which in turn causes the object to reflect sooner. To maintain physical correctness of your renderings it is advised to have the IOR of an object correspond to its real IOR. Below are six rendered samples with different Fresnel IOR. The last one is rendered with full reflection to create chrome material.
Reflection and Highlights? Wondering why V-Ray rendering engine doesn't have the highlight option built into it as previous rendering engine Flamingo? The truth is that the highlight is created by reflecting a very bright object or light in the scene. It also called lightsource. Some rendering engines use Highlight to create lightsource if there isn't any lightsource in the scene. But current V-Ray for Rhino version does not support this option. So you must create Rectangular Light or other self lit object as a lightsource for the scene.
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Other characteristics of reflectivity Every object has certain degree of reflection. Some are very strong, and some are weak. But this doesn't mean we have to apply reflection to every single object in the scene because that will increase your rendering time significantlly. Reflection Glossiness You don't always get clear reflection from reflective material. Objects like matte finish metal, wood and some plastic materials do not reflect their environment clearly due to their uneven surfaces. This is because the uneven surfaces create many reflecting angles for light to bounce around. So the reflections are not as sharp if compared to reflections from smoother surfaces. The best way to create this kind of rendering quality is playing around the Reflection Glossiness parameter under Reflection. By Default the Reflection Glossiness is set to 1, which is characteristic of a perfectly smooth surface. The lower the Highlight Glossiness is the more matte the material will be, but along with that goes longer render times. Same goes to the highlight Glossiness. Below are results from combinations of various intensities of Reflection Glossiness and Fresnel IOR. Hope these images will help you create your ideal plastic and metal materials. Fresnel IOR 1.2
1.5
1.8
2.1
2.4
2.7
Reflection Glossiness
1.0
0.9
0.8
0.7
0.6
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5.0
Chrome
Reflection Glossiness
Fresnel IOR 10
Reflection Glossiness
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
1.0
0.9
0.8
Samples of less Reflection Glossiness
0.7
0.6
Reflection Filter There is a white color (default) Filter located to the right of the Reflection. This is used to differentiate plastic and metal materials. When creating a metal reflection, set the Filter color to a brighter color of the diffuse color. When creating a plastic reflection, keep the default setting of white color. Of course you can set it to any color to mimic the filtered lenses.
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Material: Refraction Open file? Cups
- Refraction.3dm? We
are going to introduce how to add and edit transparent
materials. Select the red cup from above. Under Properties>Material, select Edit to edit the cup's material. Add transparent layer 1 . Click on the “+” to the right of the Cup_Red, and then right click on Refraction Layers. Select Add new layer. You will see a new layer (Refraction) added to the right of the window.
Transparency percentage of material 2. If you don't see the transparency from the material preview window, that's because the Diffuse layer transparency is set to black. Use this color to adjust the degree of Transparency. Click on the color and change it to white, which will give you 100% of transparency to the material
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3. Click on the Update Preview again and you will see the transparent but without its original red color. When you set the transparency to 100% white, no matter what you have for diffuse color, it will not show up. It will render like right hand side image below
The color of transparent material When you want to apply color to the material without changing its transparency setting of 100% you will have to do it with Fog Color, which is located to the lower right of the refraction dialog box 4 . Click on Fog Color and change it to the same color as the original Diffuse Color. Click the Update Preview button and you will see the red color show up on the material this time
Image on the left is what you will get. Do the same changes to the other two colors and you will get an image similar to the one on the right.
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Fog Settings Explained The appearence of Fog depends on three parameters; Fog Color, Fog Multiplier, and object size. The Fog Color is a very important factor, and the wrong color can make it hard to achieve your desired effect. It is best to set your color to a very light or desaturated version of the desired effect. The Fog multiplier is completely based on the Fog color and object size. The object’s size is important because Fog is created by calculating how much light penetrates an object, therefore a larger object will absorb more light than a smaller object. This means that a single setting will not necessarily create the same affect from object to object. The image on the left is two spheres with the same material applied to them, but the sphere on the left is 4 times larger. The images below are tests of different multipliers with a desaturated and saturated color. Fresnel IOR：1.55 Refract IOR：1.55 IOR：1.55 Fog Color：R244, G250, B230 Fog Multiplier 0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2.0
Fresnel IOR：1.55 Refract IOR：1.55 IOR：1.55 Fog Color：R175, G250, B0 Fog Multiplier 0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2.0
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The Index of Refraction IOR (Index of Refraction) is used to calculate the amount of light refracted from transparent object. The default IOR value is set to 1.55. Please see the chart for usual objects' IOR value. Material
IOR
Material
Vacuum 真空 Air 空氣 Alcohol 酒精 Crystal 水晶 Diamond 鑽石 Emerald 綠寶石
1.0 1.00029 1.329 2.0 2.417 1.57
Glass Glycerin Ice Ruby Sapphire Water
IOR 玻璃 甘油 冰 紅寶石 藍寶石 水
1.52∼1.8 1.472 1.309 1.77 1.77 1.33
Refer to images below for examples of different IOR settings. Refraction IOR 1.00
1.05
1.10
1.15
1.20
1.25
1.30
1.35
1.40
1.45
1.50
1.55
1.60
1.65
1.70
1.75
1.80
1.85
1.90
1.95
2.00
2.05
2.10
2.15
2.20
2.25
2.30
2.35
2.40
2.45
Please note that the changing the IOR in the refraction layer does not have an affect on the reflections of the object. The reflections are controlled by the fresnel IOR which is mapped in the Reflection layer. The values between the reflection layer and the refraction layer are not linked, although it is recommended that the values be the same
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The Glossiness of transparent materials Similar to reflective objects, transparent objects also have an setting for Glossiness. Refraction Glossiness will allow you to control the sharpness of an objects refractions. The Glossiness of a transparent object usually used to represent different type of glass, for example, frosted glass. Take note that a low refraction glossiness will eventually blur the object to the point that you can no longer see through the material. It also must be noted that render times will increase with lower glossiness settings.
Refraction Glossiness by default is set to 1.00, please refer to the images below for examples of different refraction glossiness settings. Images below have the Refraction IOR set to 1.55. When the setting for Refraction Glossiness remains the same, different Refraction IOR will change the Glossiness of the object.
Refraction Glossiness 1.00
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
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Similar to howthe intensity of the Fog Multiplier affects its transparency, the Refraction Glossiness becomes more pronounced in thicker objects
Refraction Glossiness 1.0
Refraction Glossiness 0.6
Refraction Glossiness 0.6 Gradient Map
Image below shows the influence of Refraction Glossiness material to objects behind it. Objects
The shadow of transparent materials There is an Affect Shadow option to the right hand bottom corner of the Refraction dialog box, by default is unchecked. When checked, the color of the transparent object will affect the color of its shadow. We recommend you have this option checked because it will allow for more realistic shadows. Images below show the difference with and without the Affect Shadows checked.
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Double-sided material Under Options of each material, you will find the Double-sided selection. The default setting is checked. This option is particularly important for transparent material. When this option is unchecked, light that enters the inside of solids will not be rendered and show up black. The reason to have this option is that sometimes you may want to disable this option when render object with translucent material (See next page) in order to get the right texture Unless you want to create some special effects, please have this option checked for the most of the time.。
Translucent material We've talked about changing the Diffuse color to get the degree of transparency we want to create before. White means 100% transparent, black means 100% opaque. You can create translucent materials with colors anywhere between white and black. But now we want to introduce a different translucent material. It is related to special light absorption materials. Open file Translucency.3dm? and render it, you will get image like below on the left. You will see that colors where partitions meet the outside box and at the base of the box are darker. This is because the thickness of the object changes and the light travel distance changes also. So the degree of light absorption varies. To create this kind of material, you have to check the Translucency option under the Refraction. Image on the right is the rendered result for Layer 02.
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Check the Translucent box under Translucency first. Thickness is for control of light pass through the object, the unit for this is unclear. Keep these three settings as default. Other items required to change include 1.Double-Sided must be unchecked so the light can get through the inside of the object. So it won't become too dark. 2. Set IOR to 1 is just fine 3.Give a smaller value to the Refraction Glossiness will help increase the glossiness area. 4. Do not use white color for the Transparency because that will turn the object to completely transparent and become dark after rendered due to absorb too much light. Do not use black color, either. That will not allow light get through the object at all. Pick a color anywhere between Val 80~150 will give you the best result. Many rendering engines use Sub-Surface Scattering (SSS) to create this kind of material. Although most of materials have certain degree of translucency, but this doesn't mean that you have to apply this kind of material to all of them. That will increase the rendering time dramatically. This material is good for creating things like: wax, skin, milk, cheese, plastic and jade which all have a little translucency in it.
Translucency is created by absorbing light to the object's surface so the color of the object will show up a little darker than its original color. If you still think that it's too dark even though the original color is set to the highest Val 255, the best way to fix it is increasing the intensity of your light in the scene.
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Material: Emissive Open File Cups - Emissive .3dm? and we are going to show you how to create a self-illuminated material. Select the green cup on the right. Under Properties>Material, click Edit to open the Material editor dialog box. Add Emissive Layer 1 . Click on the + next to the Cup_Green to pull down the layers. Right click on Emissive Layers and select Add new layer. You will see the new Emissive layer added to the right side.
Open the Emissive menu. By default the color is set to white, intensity to 1 and Transparency color to black. Click on Material Preview and you will see a completely white material ball. Render it and you will get the image like the one on the right
Self-illuminated material can make the object become a lightsource itself. It is not limited to a certain shape like a regular light type. Every part of the object can be illuminated and used as a lightsource. Self-illuminated material are perfect to create objects like: light ball, light tube, light shade, stylish lighting, cold light and lit screen. In order for illuminated objects to emit light GI must be enabled. V-Ray for Rhino 1.0
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Adjust the Intensity By Default the Intensity is set to 1. Below images are rendered with Intensity of 3 (L) and 5 ®.
Adjust the color Click on the color box to change to a different color. Notice that if the setting of the Intensity is too high, the color of the object itself will become close to white. Only the light emitted from the selfilluminated object will carry the correct color. It is not recommended to use self emitting materials as a normal lightsource. Just make it as a decorative object in the scene. Please refer to below image chart for results of various Emissive Intensities. By controlling the degree of Transparency under the Emissive Color, you can still keep the diffuse color of the object. For example, when the Intensity is higher than 2, the diffuse color is washed out and become white. To avoid the self-illuminated object become white, please also refer to the Color Mapping on page 74.
Emissive Color：R200, G161, B82 Emissive Transparency：R100, G100, B100 Intensity
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Diffuse Color：R155, G155, B155 Diffuse Transparency：R0, G0, B0
0.0
0.1
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Texture Editor Setting Aside from using colors for self-illuminated materials, you can also use texture maps as light source. 1 . Click on the “m” to the right of the Color under Emissive control panel 2 . The Texture Editor will then open up. Select Bitmap from Type's pull down menu and you will see the control panel show up to the right.
3.Under Bitmap click on the “m” to the
4. After the bitmap is selected, the “m” now
right of the File and pick a bitmap to use as
becomes “M”. Click the Update button to
the light source
preview the bitmap. Click Apply and you can use this bitmap as the light source
5. Click on Update Preview and you will see the Bitmap is now on the material ball. Render it and you will get the result as the image on the right.
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Please note that if any type of map is being used in Texture Editor, the Color and Intensity under Emissive will no longer function. You can't use these two options to control the brightness of the material any more. You need to click on the “M” and go back to the Texture Editor and adjust the multiplier there. All other control options in the Texture Editor work the same. Click on the “M” and go back to the Texture Editor. Pay special attention to below options as these options are often used for controlling the Bitmap texture map Multiplier: Controls the intensity of the Bitmap. Default set to 1. Increasing this number will intensify the color tone, brightness and color contrast. Blur under Bitmap: Controls the blurriness of the Bitmap. By default this is set to 0.15. Setting this to 0 will not have any blur effect to the Bitmap. Override: Use this parameter to set the gamma value. Repeat: Used to control the U and V tiling of the Bitmap. Increasing the number will cause the bitmap to be repeated withing the mapping coordinates Rotation: Adjust the degree of rotation of the Bitmap.
The intensity of self-illuminated materials (ipod image) is independent of the environment settings. The bitmap will still render with its own intensity setting. Use the same way to create cold light effect. Also showed below are two other examples.
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Material: Texture Mapping Texture Mapping Most of the time we can't just use reflection and refraction to create a material for an object. For example: stone, wood, paintings, packages, and textiles. We must use some texture maps to create these materials. Below are some examples of using texture map for rendering.
Open file Teapot Matte.3dm? Render the scene and you will an image similar to the one on the left with a reflection material applied to it. The Image to the right is the result of applying brushed metal texture map. You can see clear difference between these two images.
01.
Click
on
the
teapot.
Under
Properties>Material, click on Edit to open the Material Editor. Pull down the Diffuse menu from the right and click on the “m” next to the Color to
02. Select Bitmap from Type's pull down menu
open the Texture Editor
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03. Click on the “m” to the right of File
04. Click Update to preview the texture map.
under Bitmap to select a Bitmap file
05. Render it. Since we didn't assign custom
06.Use mapping channels to adjust texture
UVs for the texture map, it will use the object's
UVS. Select the teapot first, switch to
surface UVs to render
Mapping dialog under Properties
07. Make sure Show advanced UI is checked
08. Click on Add to create a new mapping channel
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09. Pull down the projection menu and
10. Click on Show Mapping to display mapping
change it from surface to planar
widget in the window
Surface projection will not show a widget. Render and you will get an image like the one below. Since the Planar projection projects the Bitmap from top down, the texture map is not
11. Under Rotation, make the x value -90, then
yet showing the correct direction. Rotate the
left click on empty place. This will rotate the
mapping widget to change the direction of
mapping widget 90 degree off the x direction
projection.
and projects the Bitmap from front to back
You could also modify the mapping widget with standard commands in the viewport
Image on the left shows the mapping widget rotated 90 degree; on the right is the rendered result.
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Mapping types and adjustment Rhino has several different types of UV projections: Surface, Planar, Box, Spherical, Cylindrical and Capped cylindrical. Rhino sets the default to Surface if there is no other projection assigned to the object and render the object according to its UV directions. When changed to a different projection. the default size of mapping widget is set to the perimeter of the object. Show Mapping is used to display the mapping widget in the scene. Within the working window, the mapping widget can be moved, rotated and scaled. An object can be set up to have multiple mappings. This is done through using multiple mapping channels. Click Add in the mapping properties box to create a new channel. Any maps that are intended to correspond with certain mapping channels must be specifed through the Texture Editor in the Material Editor. Under UV make sure that mapping is changed to Explicit Map Channel and then change the map channel underneath to correspond with the desired channel. Type ofmapping, size and position of Mapping Widget, and project direction will all affect the projection on the object. Of course, those will also affect the final render result. Below are examples using teapot to show different UV settings.
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Box
Spherical
Cylindrical
Click on F10 to show the control point for the Mapping widget. Move those to adjust the size of the widget
Material: Bump map Bump map Although we can use Bitmap for most materials there are some textures like wall surfaces, tile, wood, oil painting, leather and water, which all have the uneven surfaces. We must use bump maps in order to create them. 1. Click on the teapot and open the Material
2. Select Bitmap under the Type pull down
Editor to edit the Bump map of the teapot. In
menu
the Maps section of the Material Editor, check Bump and click on the “m” to open the Texture Editor.
Only images can for bump mapping in V-Ray for Rhino
3. Click on the ”m” to the right of Bitmap,
4. After importing the map, if the Bump map
select the same brushed metal material as
is the same as the Diffuse map, make sure
used in Diffuse for the teapot
the U, V Repeat under UVW Transform have the same value. For example, if Bump map is using U: 2 and V: 2, the Diffuse map should be the same. Otherwise, these two maps will not align correctly. Also, set the Multiplier on the left side with smaller value like 0.1. If set the Value too high will result an unnatural look of material
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Image on the left is the result of using only brushed metal Bitmap. The surface of the teapot looks very smooth. Image on the right is rendered with Bump map added to the teapot and its handle. You can see the Bump texture within the brushed metal and handle.
Earlier we talked about using reflection glossiness to adjust reflecting material's glossiness and create a frosted look. If we add a Bump map to it now will make the object look even better. The image on the left is using only reflection glossiness. The image on the right has Bump map added.
Below are some examples of textures created with Bump map.
Bump maps are created using the grayscale of the Bitmap to set the high and low texture. The bright part of the Bitmap is considered as high part and the dark is low. The Bump map is seen more clearly at the part where the object reflects the most of the light. Using Bump map texture to create bumped texture is only a visual effect, not the true surface of the object. Look at the edge of the object and you will still see the smooth surface. Displacement is the way to actually change the geometry of an object with a bitmap, but currently V-Ray for Rhino 1.0 is not supporting this function.
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Material: Transparency What's Transparency Mapping? Transparency mapping is a method of adjusting the transparency of either maps or certain material properties. This is used mostly for creating product logo, sticker, decals, and numbers. Depending on your needs it may be beneficial to model the actual object in the scene (i.e. if a raised logo show close up), but using transparency maps is a quick, easy, and simple way to acheive the desired effect. Open File Cup - Decals.3dm?and render it. You will get the image on the left. The one on the right is the decal that we will use.
You will get the left image if you apply the texture map directly without transparency map. The black background of the texture map is blocking part of the cup. The image on the right is rendered with transparency map.
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1. Open the Material Editor and select Cup_Red; right click on Diffuse Layers to add a new layer and you will have the dialog window as image on the right. A Diffuse1 control panel is added under the Diffuse
2.Click on the “m” at the right of Transparency to enter the Texture Editor. Load the Bitmap for the transparency texture map. Make sure you uncheck the Tile first to avoid repeating this Bitmap on the object Use Photoshop, PhotoImpact or a similar image editing software to create a black and white image and save as .bmp, .jpg or .png.
3. Use Diffuse1 color to edit the color for
A rendering of the object should be
this Transparency map. Click on the “m” at
s i m i l a r t o t h e i m a g e b e l o w. T h e
the right of Color to add more texture to
Transparency map is covering the entire
this map if needed
cup. That's because there is no mapping applied to this cup yet.
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4. Under Properties>Mapping, add a new channel. Change the projection to Planar and adjust the mapping widget's size and position as image showed below. If the Tile remains checked, it will render as the image on the right
The logic of Transparency maps The idea behind Transparency maps is using a grayscale image to determine which parts of an object will be visable. Black areas will conceal and white areas will allow it to be visable. A tone of gray will change to some degree of transparency. The white area has the color assigned in Diffuse1 and end up showing on the surface of the object after rendered. For the cup example above, after assigning a mask to the Transparency, the red color of the cup is affected by the white area of the mask and no longer showing red. The second layer’s color in the diagram below is used to cover the white area of the first layer.
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Other uses of transparency There are many ways to use transparency. Its not just used as a mask for text. Here are some other examples of different uses. First, we will use a gradient Bitmap as the Diffuse Transparency mask, let the yellow color of Diffuse1 show through the white area at the cup and create two gradient colors on the cup as image on the right. This is the better way then using a gradient Bitmap directly as the Diffuse texture because of its flexibility of changing colors. If you use a bitmap you will have to make another Bitmap for any changes or modifications
The next example is using another grayscale Bitmap as the transparency mask. Although it is not a gradient image it works exactly the same.
The third example is adding another Diffuse2 layer, and assigning a 0 and a 180 degree gradient Bitmap to Diffuse and Diffuse1 in Transparency. Give the Diffuse2 a third color to create this threecolor gradient rendering effect for the cup.
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Another example is to use gradient color in a transparent material. As in our previous examples, use a gradient grayscale Bitmap as the Diffuse Transparency mask. Add a Refraction layer to create the half transparent and half opaque effect.
Our next example is similar to the Third one. The only difference is we are adding a Refraction layer, and changing the Transparency color of Diffuse2 to white. This will make the white area at the middle become transparent. Rendered image as on the right
The example above can not have the transparent quality at the top and bottom of the cup because of the black color in the grayscale gradient Bitmap. The last example here is to use a pre-made gradient Bitmap as the Refraction Transparency map. Set the Diffuse Transparency to white, and then assign the Bitmap to the Refraction map
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Illumination: Environmental Lighting Lighting plays a key role in the rendering process. You simply can't get a good rendering result without a good lighting environment. Light sources are divided into direct and indirect lighting. Direct lighting is using the light command to create Rectangular Light, Omni Light, Spot Light and Linear Light and use directly on the object. Indirect lighting means object receives light from a broader source, like an Environment Light and Radiant light. Let's do a test first Open the file Cup Illumination.3dm there aren’t any lights in the scene. The light source will be from Environment light.
1. So far the cup and ground are using the same Val230 off white color. Render it with the
GI
default setting to 1 and get the result as image shown on the right
2. Increase the GI value to 2 without changing the color, the result is shown on the right
3. Do not change the GI value and change the Brightness to Val127 under the Texture Editor. Render it again and the result is very close to the first image on the top
The reason for doing this test is to let users understand the importance between lighting and material. Should adjustments be made to the material first or the lighting first?
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The answer is easy. Of course the lighting is more important! Lighting must be adjusted first! From the second rendering you can see that there is too much light in the image because of the setting of intensity of GI changed to 2. Here is one more example to understand this. If there is a white ceramic sink or tub in the bathroom, it will look black without any light source in the bathroom. You wouldn’t try to adjust the brightness of the white ceramic under this condition. And also, from the material setting point of view, how can you get even brighter when the color is set to val255? It would be ridiculous even trying to create an Emissive or self-illuminated material on the object at this time. The only way to improve the lighting for dark place is adjusting the brightness! From intensify the Brightness of Environment light and regular light, or even add more lights to the scene are the right ways to improve the illumination. It's not appropriate to adjust the Brightness of the material assigned to the object to improve the illumination. You will be in trouble if you try to improve an image by changing the materials instead of creating proper illumination. In other words, whenever the intensity of the illumination in a scene changes, it will affect the appearance of the material's texture. You would have to adjust the material again if you worked like this. Take another look at the white cup in the previous example \. If you want to change the cup's color to red, under the GI setting of 2, you must pick a real dark red in order to render the color correctly. What if the user wants a lighter red color? Or what will happen if there are more lights added to the scene? Are you going to use some extra walls to block the light? Many questions remain… It is very hard to predict the render result under incorrect illumination. That's because the output does not accurately reflect the inputted settings. Interior or Exterior? When facing the task of illumination, separate it into interior illumination and exterior illumination. For example, place an object on the ground without any wall surrounds it to block the light. This would be exterior illumination. Interior means that the object is blocked or enclosed by space in a way that the environment light does not have a direct effect on the object. The image on the top shows open space illumination and image below that shows the semi-open space illumination. The next image down shows the same semi-open space but adds two openings in the wall. The brightness increased due these openings. The last image shows that different locations for openings will also affect the brightness of the scene
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Techniques to adjust the Brightness Before render the scene, try to finish all of the modeling that is needed. This will simplify adjusting the illumination. The number of objects, object location, material type, color and even size will all affect the illumination in some way, but if the environment light is correctly determined it will make the rest of the process easier. As with digital photography, in order to get the correct colors, you must to get the correct the white balance first. V-Ray's Environment light and lighting brightness are not controlled by a specific lighting unit, so it is impossible to find the regular brightness for white balance setting. You can only try to get the correct setting by rendering the result to evaluate if the illumination is enough in the scene. Open the file Cup - Illumination.3dm again. This is an easy open space example, there is no light added to the scene and the Environment light is currently set to 1. Using the floor color to get the correct white balance reading is better because it takes the most part of the render result. Using the white floor color to evaluate the white balance is the first step. Make sure the color under Material Editor is set between Val180~230, not Val255. If we set it to Val255, it will render extremely bright white without any depth after adding lights to the scene. So it is always a good idea to set the floor color brightness a little bit lower to save some room for more light sources later. 1. Assign the Val 230 color to floor, R191 G19 B19 red
2. Re-assign the R255 G100 B100 red color to the cup
color to cup first.
and render; you will get the result as below.
From the two images above we can see that the colors of the floor and cup are rendered very close to actual colors, which means the Environment lighting is set to correct intensity and brightness for creating good illumination. If the intensity was too strong, it would make the floor and cup appear far to bright and would not mimic the actual material color. You should not adjust the brightness or intensity of the environment light if no other lights will be added to the scene. While adding lights you should preform this test again to maintain the appropriate illumination levels. As long as the illumination is under control, you can safely pick the colors or textures for the object. Default setting is 1 for Environment light. In reality you shouldn't increase this number despite its location of interior or exterior. Please refer to page 56 for “Environment light for semi-open space”.
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HDR Environments Instead of using a color for an environment it is possible to use an image for your environment. VRay supports HDR image based lighting. Open file Cups - GI HDR.3dm 1 . Open V-Ray for Rhino's Render Options. Open the Environment menu and click on the “m” at the right of GI to enter the Texture Editor
2. Choose Bitmap from Type, click on “m” beside File and import an .hdr file.
HDR courtesy of Wouter Wynen http://www.aversis.be 3. Make sure you check the Environment radio button under UVW after the file is selected. Render it and you will get the image on the right. You can see the difference between this image and the image using only color for Environment light source.
4. If you want the objects to reflect the HDR image Environment as well, you can assign the same
HDR
image
to
the
Environment
Background. Make sure the UVW is set to Environment. After the Background HDR is added, the result is the image on the right
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Below are three images rendered with different HDR images as the Environment light sources. You can see the dramatic differences between each image.
Understand that because most HDRs are prepared by a third party, it may take sometime to adjust the intensity to fit your scene and lighting needs. Sometimes you may also need to adjust the HDR's Horizontal angle to better cooperate your own lighting direction. Although an HDR image has better control of its brightness than a normal 24 bit Bitmap, it still can not recreate the light source and brightness in the nature. So normally it's used only for Environment light source. Also, unless the light source is very bright in HDR image, the rendered shadow is lighter and not very clear. You will need to add more light in the scene to get the better shadows in this case.
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Bitmap Environments If you do not have an HDR image, a regular Bitmap can also be used as an Environment light source. However, it is highly recommended that you use HDR images in stead of standard bitmaps. Standard bitmaps will have less brightness control, a less obvious light source, and softer shadows. Standard Images are easier to obtain, and with a bit of time and tweeking they can create a decent environment. The three images on the right are rendered with different Bitmaps.
Compared to HDR
environments, it is not easy to find where the light comes from and the shadow is not very clear.
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Environment for semi-open space We used an open space Environment in our previous example. Now we will try a semi-open interior space to see the differences between the two. Open file GI Environment.3dm In the scene we have an enclosed cube with an opening on the right side. There are some objects placed on the wall next to the opening and there is no light in the box. All objects used a gray color (RGB 190,190,190), the current GI Intensity is 2, and the GI color is light blue. Render it and you will get the almost black image on the right. This result is due to a lack of direct light in the scene and only a small opening allows the Environment light to come in.
Increase the GI Intensity to 4 and render it
Increase the GI to 8 and render again. The
again. The result below is little bit brighter.
result is closer to reasonable illumination.
When we begin to set up the illumination for an interior space, first we need to check how many openings allow light in (this also includes transparent object like a window or door). You must also determine whether you want the lighting in the final result to be from the environment or from direct lighting because this will determine how you set up the environment.
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Even if the Environment is set to the desired setting, you may still encounter problems later when you adjust materials for objects in the scene. When adding additional lights to the scene and adjusting the materials, its unlikely you will get you desired result on your first render.
It is
important, especially for interior scenes, that you determine the views that are going to be rendered. This is because a different view may require different lights or intensities to obtain the desired result. This is illustrated in the two images below. The images are two renderings of the same model and the same lighting set up. The one on the left is an exterior veiw and the one on the right is an interior view.
Irradiant light Please keep the scene that has the GI intensity of 8. It's easy to spot some blotches in those images from previous page. This happens when indirect lighting affects the object. It is more obvious when the indirect lighting gets stronger, and this only happens when Irradiance Map GI engine is used. This is the result of a lack of hemispheric subdivs and samples during the process of transferring lighting data to the image. Open V-Ray for Rhino's Render Options and then pulls down the Irradiance Map menu. Change the Subdivs value from default 50 to 100, and Sample from default 20 to 40. Render again and you will find it takes longer to render but yeilds a better result such as the image on the right. In fact, for most cases, you don't have to increase these values as this high to get a better result if there is proper light and brightness in the scene.
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GI Engines V-Ray has the ability to use different methods for calculating the light within a scene. To do this VRay breaks the calculation into two types of light. The first is the primary bounce, which is the first light bounce coming directly from a light source. The second type is the secondary bounce, which is all of the other light bounces in the scene. With V-Ray you can specify exactly which method of calculation for each of these bounces. Open the Indirect Illumination control panel under Options. There are Primary Engine and Secondary Engine in the panel below.
Primary Engine There are four options for Primary Engine: Irradiance Map, Photon Map, Quasi Monte-Carlo and Light Cache. Default is set to Irradiance Map。
Secondary Engine There are three options for Secondary Engine: Photon Map, Quasi Monte-Carlo and Light Cache. Default is set to Quasi Monte-Carlo or you can select None to not use this Engine. When switching between the different engines, the settings available will also change according to the assigned engine.
Primary Engine: Irradiance Map Open file Cups - Irrdiance Map.3dm?and open the Irradiance Map's control panel under Options. There is a very important setting option here related to image quality: Min Rate and Max Rate. Default for Min Rate and Max Rate are -3 and 0 respectively. They are currently -8 and -7 in the file. Render it and you will get image to the right. Notice that the calculation speed is very fast, but the quality of the shadow and cups is poor.
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Min Rate: controls the minimum sampling for each pixel. 0 value means 1 pixel as 1 sample. Value of -1 means 2 pixels as 1 sample. Value of -2 means 4 pixels as 1 sample and so on. Smaller values means fewer samples being taken from the object, so the render qualities of shadow, reflection and refraction are not very good. Max Rate: controls the maximum sampling for each pixel. 0= 1 pixel uses 1 sample. 1= 1 pixel uses 4 samples. 2= 1 pixel uses 8 samples and so on. Smaller values means fewer total samples used to calculate the light. A larger value will result in better quality but longer render time. Default settings of -3 and 0 represents four passes of render job. From -3, -2, -1 to 0. So you can see the Prepass 1 of 4 to Prepass 4 of 4 from the render progress dialog box. According to definitions above, having the same number of prepasses does not mean the same render quality. If you render with Irradiance Map as Primary Engine, you can give a smaller set of numbers for Min and Max Rate to produce faster previews of the lighting and material settings in a scene. For example: -6 and -5 or -4 to -3. Although the quality may not be good enough for a final image, it is ok for a preview. After the scene is finalized, then you can render with higher value to get the best final quality image. The image on the left is showing Irradiance Map's fouth Prepass calculation of Min Rate: -3 and Max Rate: 0.The Image on the right is the final result.
The image on the left is showing the second Prepass of -4 and -3. Image on the right is the final result.
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The image on the left is showing the second Prepass of -3 and -2. Image on the right is the final result.
The image on the left is showing -3 to 0. Image on the right is showing -3 to 1. Although the one on the right has the better final result, the difference is very little.
If an image has a sufficient min/max rate (-3,0) yet still produces blochiness then the subdivisions and the samples can be increased.
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When Min Rate and Max Rate are too low, “leaking light” tends to happens even if the objects are joined together. See image on the left for example. This is due to lack of Samples when calculating the Prepass. Of course, this only happens when using Irradiance Map for the primary engine. The image on the left is rendered with Min Rate and Max Rate of -4 and -3. You can see light comes through the corner clearly. Increase the value to -3 and 0 and you will see an improvement as seen in the image on the right.
Primary Engine: Quasi Monte-Carlo When using QMC as the Primary Engine, the render result will not have any blotchiness or leaking light as seen when using Irradiance Map. There is no need for a Prepass either. While the QMC engine will also create image which is very realistic, it does take a long time to render. The image on the left is rendered with Irradiance Mapping and the image on the right is rendered with QMC. Although the one on the right looks dusty, but compare to the perfect pure color image on the left, the QMC is more realistic.
Depending on your settings you may get very sandy looking image with QMC as Primary Engine. To solve this problem, you can either increase the Subdivisions from default 8 to a higher value under QMC's control panel V-Ray for Rhino 1.0
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Secondary Engine: Light Cache Light Cache is used to calculate the light distribution in the scene. Its calculation method is very similar to Photon Mapping, but the total opposite. Photon Map starts with a straight path from the light source and collects light energy along way. Light Cache starts from the camera instead. Some good points about using Light Cache include: it doesn't have many setting options to deal with, it renders quickly and calculates light correctly. On the downside, the user has to decide the amount of subdivs. This value is related to the resolution of the image. The image on the left is rendered with combination of Irradiance Map and QMC. The image on the right is rendered with combination of Irradiance Map and Light Cache.
Subdivions are the most important factor for Light Cache. Subdivisions are used to decide how many light paths are traced from the camera to calculate the light distribution. The actual number of samples is the square of the number of Subdivisions. With the default setting of 1000 for example, the actual number of paths will be 1,000,000. When the image resolution is higher, this number must set it higher as well. A lower number could result in an incorrect solution for the image. The best way to determine what the idea amount of subdivions is, is to set a higher number first and render. Look at the progress window and monitor the progress of subdivisions and calculate the number according to the percentage. Say the subdivisions number is 1000 for example, when the subdivisions is half way through its calculation, the rendering window's black dots are almost gone, that means you only need to set the number between 500~600 and you will get the correct render result. If the process is done but you still have a lot of black dots in the window, that means the number of subdivisions is not enough and result will be off. The image below is showing Light Cache calculation that still has a lot of black dots in the image.
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Another setting you should pay attention to is the sample size. This is used to define the distance between each path. Smaller numbers will give you more detail and a clearer image, but use more memory to render. Larger number will give you smoother image, but could lose details. Please view the images below from top to bottom. Both Primary and Secondary bounces are using Light Cache. The images on the left are using 0.02 as the Sample Size. The images on the right are using 0.03 as the Sample Size. The images below only show difference between Sample Sizes.
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Depth of Field What is Depth of Field? We must use photography to explain Depth of Field. When taking a photo with a camera, the two most important things are focus and exposure. If it's not properly focused, the image will become blurry. Incorrect exposure will also affect the result. Depth of Field is related to focus. Open V-Ray for Rhino's Render Options. Pull down Camera control menu and you will see Depth of Field below. By Default it is off, check it if you want to have the depth of Field in the final rendering. The most important control item is Override Focal Dist. Adding Depth of Field to the image is to make it more realistic.
How to find out the current setting of focus distance of the camera? 1 Open file Cups - Depth of Field.3dm? as menu on the right, in perspective view, right click on Viewport Title and select Show Camera. See image below, the narrow point in the scene is the lens of the camera, the point on the opposite side is the Target.
2. Use Polyline tool to draw a straight line, open snap point mode, left click on the camera point and move the mouse over to Target point. Look at the distance window below and that's the number to use for the Override Focal Dist. In this case, 62.3724 is the number to use. Render it and you will get the rendering with Depth of Field effect. By default the focal distance is determined by the camera, but if you want to change the focal distance without changing the camera the you can use this function.
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Hit the Tab key when the cursor is locked to the Target point, and then move the mouse. You will find the direction from camera to Target point is locked. Move the cursor and the number for the distance will change accordingly. Move the cursor to desire focus location and memorize the number below. Use this number for the Override Focal Dist. and it becomes the new focus distance. Hit the Tap key again to unlock the direction The image on the left is rendered without Depth of Field and image on the right is rendered with it's Aperture set to 1.0 The Depth of Field has already show up in the image and the focus point is at the green cup.
Size of Aperture V-Ray does not use f-stops to control the amount of light as normal cameras do. A smaller number has less of an effect on Depth of Field. A larger number will make the object very blurry and takes longer time to render, especially when calculating the edge of object for Depth of Field. So we recommend you start with smaller number and move your way up if you need stronger effect.
Change Focal Distance Go back to Camera's control panel, set the Aperture to 1.0, then input 47 for the Override Focal Dist. and make it closer to the red cup's opening edge. Render it and will get the image on the left, Green and orange cup becomes blurry. The image on the right is rendered with Override Focal Dist, changed to 72, approximately at the front edge of the orange cup. So now the yellow and green cups become blurry.
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Below are some images showing more example of Depth of Field.
The glass cups are products of Nachtmann from Germany。 V-Ray for Rhino 1.0
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Caustics What are Caustics? Caustics are a lighting phenomena created by some materials, for example, metal, jewelry, glass or liquid which rebound light around the object. It is more obvious when the light is stronger
Open file Cups - Caustics.3dm and open V-Ray for Rhino's Render Options. Pull down the Caustic control panel at the bottom. Check the on button to enable Caustics.
After you start rendering, the process window will show the lighting information. As the caustic effect in the scene first. It won't take much time to render if the Caustic Subdivs and light setting are using default setting
Photons The image on the left is rendered without caustics. The image on the right is rendered with caustics enabled. All of the settings are using the default setting. Due to the rebound of light, the cups look brighter at the right.
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Go to the Caustics control panel. Change the Max Photons setting from 50 to 300. Render and the result should look like the image on the right. Compare this with the image on the last page you will find the Caustic effect is greater this time and smoother Usually it's easier to spot the Caustic effect in a darker scene. If the scene is brighter, you can try increase the Multiplier to offset the difference.
If you want better control of the quality of the caustics, you can change the light settings. With the light selected, go the light properties window and increase the caustic subdivions from 1000 to 2000. Be aware that this will increase the prepare time for render Caustic effect. The image on the right is rendered with Caustic Subdivs set to 3000, you can see the better quality of Caustic effect in this case.
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Liquid inside a transparent glass Strange image This requires some skills, and mainly comes from a problem with the model. Open file Cup - Liquid.3dm The liquid and the glass are coplanar, which causes a problem with reading the materials of the model. Render it and you will get image as below
Use Scale or Scale2D to increase the size of liquid and that will solve the problem
If you scaled the liquid down, which would be more physically correct, the image would not look realistic.
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Adjusting Camera Rotate the camera Hold both Alt and Shift, then right click the mouse to rotate the camera. This will make the image more dynamic.。
Adjusting the lens Right click on the Perspective window title, select the Viewport Properties from below. See image below, you can input desire lens length here. A smaller number for wide angle lens or a larger number for telescope lens. If you don't want to have any significant deformation of the objects, try to avoid using wide angle lens. A normal product can get the best perspective by using Rhino's default 50mm lens. Use 22~35mm lens for an interior shot.
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Light and Shadow The quality of Shadow Unless shadows are disabled in global settings, all objects will cast shadows. The quality of shadow is controlled by subdivions under light properties dialog box. Select the rectangular light and under Sampling>Subdivs change the default number of 8 to 32. The higher number will cost more time to render, but will produce smooth shadows. The image on the left is rendered with Subdivs set to 8; the image on the right is set to 32.
Radius for Shadow edge When using Point light, Spotlight and Direction light for light source, the shadow edge will be very sharp. To soften it, adjust the Radius in the Shadow dialog box. Using Directional Light here for example, Image on the left is rendered with Radius set to 0. Image on the right is rendered with Radius increased to 0.05
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Lighting Parameters All of the light types' detailed here are supported by V-Ray. Each of the types has some unique parameters, but there are a several parameters that are consistent between all of the light types. Point Light and Spotlight require that the user set the Decay type: Linear, Inverse and Inverse Square. The last two will decay dramatically, so when using Inverse or Inverse Square, you must increase the multiplier. That means that point lights and spotlights are greatly affected by the distantance from the object, so it will require more adjustments with these lights. The Intensity of Directional Light will not Decay at all in any distance, it usually used outside to mimic the sunlight. Rectangular Light
Directional Light
Point Light
Spotlight
For interior, use Directional Light to create strong sunlight come in from outside.
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Color Mapping The function of Color Mapping Color Mapping is a function to replace color from the rendered image. Sometimes the screen can't show extremely bright color correctly. Use Color Mapping to fix this problem when it happens. Types of Color Mapping Open the Color Mapping panel under Options, V-Ray default is set to the Linear Multiply option. Linear Multiply is using an object's brightness to create color. So Brightness over Val255 will be discarded. Objects under strong light usually get washed out to white color, like the image on the left. Exponential uses color intensity to control brightness and prevents this wash out situation, but the objects' color will become light, like image on the right.
HSV Exponential and Exponential are very similar, but HVS will keep the tone and intensity of the color, like the image on the bottom left. Intensity Exponential can maintain the RGB ratio, and will only affect the color intensity, like the image on the bottom right
Note that under very strong light conditions, these three index color control will cause the scene to be rendered darker. If under an average brightness scene, the render image will lose some depth due to the colors evening out, especially in off white scene, you can get a totally different effect.
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Antialiasing V-Ray’s default image sampler is Adaptive Subdivision. See image below on the left. These thin lines were rendered with the default settings and had some broken lines in towards the back of the plane. Adaptive Subdivisions Sampler Open the image Sampler under Options, the V-Ray default is Adaptive Subdivisions with a min rate of -1 and a max rate of 2. For this example, set the Min rate directly to 0 will fix those broken lines, as image on the right. Under most circumstances, use default Sampler for Adaptive Subdivision can get a pretty goof result already.
Fixed Rate Sampler This sampler uses a standard rate of subdivisions for computing antialiasing. This is generally will take longer to compute because in areas that do not need a detailed sampling(i.e. a smooth, flat plane) will get the same amount of sampling as a very detailed portion(i.e. a mesh screen). This sampler can produce very predictable and consistent renders. Adaptive QMC Sampler Adaptive QMC is a better sampler for detailed scenes with blurry effects. For example, scenes with tiny seams, thin lines, reflection or refraction glossiness, Depth of field, and texture on material map. Using Adaptive QMC for above situations can get a better quality image. By default, min Subdivisions is set to 1. This is the minimum number of samples assign to each pixel. In most cases, you don't have to increase its value. Max Subdivs is the maximum number of samples assign to each pixel, and default it is set to 4. For better image quality you should increase this value. Of course higher number will result in longer rendering time. Those who want to have high quality image should switch to Adaptive QMC Sampler when calculating images.
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Output Image Resolution V-Ray can override the sizes set up by Rhino. Open V-Ray for Rhino's Render Options. Open the Output control menu and check the box to Override Rhino to have V-Ray define the image size. There are several size presets in V-Ray to choose from. Users can also provide a custom the size. The unit used is pixels. The Image Aspect below is the height-width ratio for current size. Click on the “L” to lock in this ratio. When one of the height or width has changed, V-Ray will calculate the other value automatically according to this ratio. Saving Output Check the Save File button under the Render Output and then click on the “…” to set up the file path, and type the file name. When V-Ray finishes rendering, the file will be saved accordingly. Please note that next rendering will override the previous one with the exact same path, type and name.
The Pixel Aspect option is used to control the aspect ratio of the pixel. Please see the two images below
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V-Ray frame buffer Tools The V-Ray frame buffer has some useful tools. Please see discussions below for each tool
Switch back and forth between different color channels to display the image, which is also
Click on this icon and
including Alpha Channel and grayscale to display
mouse is pointed to first during the last portion of the
the image in black and white.
V-Ray will render where the
rendering process. This is very helpful if you want to see the final result of particular part of the image. If the result is not what you want, hit ESC to end
Save the image.
rendering process right the way Clear the image.
This icon opens the color and brightness control
click this icon to open the information dialog box.
dialog box. Click on both X
Right click on the rendering window to display pixel
and X to update the color
information. Right-clicking within the rendering
adjustment and brightness
window can also open this dialog box; release the mouse to close this box
Click on this icon to open the frame stamp bar. Click on the far left icon to show the frame stamp at the bottom of the rendering window. By default the contains the V-Ray version and render time. This information will be saved with the file.
Mouse operation Ctrl+left key: Zoom in Ctrl+right key: Zoom out Double click on left key: back to original size Middle wheel: move zoomed in image
Keyboard Operation
+ / -: Zoom in and out * : go back to original size Arrow keys: move zoomed in image
Right key: show pixel information V-Ray for Rhino 1.0
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Final Thoughts The last few tips Here we offer some tips and experiments from other users and hope to save some time and increase the image quality 01 Under Render Options>System, try to adjust the render division. In some cases a smaller value will render faster, in others large values will. As you do some test renders change the value and see if it renders faster or slower.
02 . Use RenderWindow command to render a small part of the entire image for testing render settings. Make sure you don't click on something else with mouse while rendering. It will terminate the process. 03 .Before you determine the best lighting for the scene, hide all objects except the floor and render a big area of that floor. This will give you the brightness of the scene easier and faster. 04 . All Subdivs will affect the quality of the image. Try using smaller values before you render the final image. 05 . Use the minimum amount of lights in the scene to save rendering time 06 . Raise those objects that sit on the floor a little bit to have better shadow quality and to avoid overlapping geometry. 07 . Use Depth of Field to increase the realism of the image. 08 . Add more memory to your machine. 09 . Use image editing software to improve the final image 10 . Use your spare time to render If you think V-Ray for Rhino is awesome, please recommend it to your friends. everyone enjoys playing with it!
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Finally, hope
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