INTERACTIVE USER GUIDE
Exact Surfacing for the Precise Reproduction of Surfaces
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Revision
Aug 2009 May 2010
First Release Updates for Geomagic Studio 12
About Geomagic Inc. Geomagic, Inc. is a worldwide software and services company headquartered in Research Triangle P ark, North Carolina (U.S.A.), with subsidiaries in Europe and Asia and distributors worldwide. Geomagic is the market leader in digital shape sampling and processing (DSSP) with a vision of mass customization, technology innovation, and business performance. Geomagic software enables customers to accelerate product development cycles and ensure quality at every step. More than 5,000 professionals use Geomagic software and services across diverse industries including automotive, aerospace, medical, and consumer products.
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Table of Contents
1
GUIDE DESCRIPTION
5
1.1
Introduction
5
2
PRECISE REPRODUCTION OF SURFACES
8
2.1
Point Phase
8
2.2
Polygon Phase
12
2.2.1 2.2.1.1 2.2.1.2 2.2.2
2.3 2.3.1 1.1.2 1.1.3
Optional Output Steps Saving the Polygon Object for use by Other Apps Exporting a Profile from a Polygon Object Choosing the Next Phase
Exact Surfaces Phase Emphasis on Curved Regions Legacy Workflow AutoSurface
13 13 13 14 15 15 18 21
1
GUIDE DESCRIPTION This Guide leads an advanced beginner through two fundamental workflows that yield precise reproduction of a scanned part. The goal is to highlight the differences and expected results of each workflow, enabling you to choose the best workflow for a real-life project. The Guide requires Geomagic Studio 12 with the Geomagic Capture, Geomagic Wrap, and Geomagic Exact Surfaces module licenses.
1.1 Introduction The fundamental workflows: • Precise reproduction of underlying data with emphasis on curved regions (data capture, cleanup, conversion to a polygon object, refinement of the polygon object, surfacing with the “Detect Contours” method in the Exact Surfaces Phase, and exporting to CAD). An advantage of this technique is that the resulting CAD object has distinct faces for t he curved regions, thus allowing curved regions to be further engineered in the external system if necessary. See section 2.3.1, “Exact Surfaces Phase with Emphasis on Curved Regions.” ( Preferred Workflow ) • Precise reproduction of underlying data (“legacy workflow”) (data capture, cleanup, conversion to a polygon object, refinement of the polygon object, and surfacing with the “Detect Curvature” method in the Exact Surfaces Phase). This is a legacy workflow that customers find useful in certain situations —“Precise reproduction of underlying data with emphasis on curved regions” is typically preferred over this workflow. S ee section 2.3.2, “Exact Surfaces Phase Legacy Workflow”.
In Geomagic Studio, an object always exists in one of several Phases: • Point Phase: the state of an object when it is a collection of scanned points. • Polygon Phase: the state of an object when its appearance is approximated by drawing a blue triangular surface between every three data points. • Surface Phase (either Exact Surfaces Phase or Parametric Surfaces Phase): the state of an object when a reproducible surface is being applied over its underlying polygon mesh.. This Guide describes the Exact Surfaces Phase. • CAD Phase: the state of an object when it is ready for t rimming or for Boolean operations to be performed.
2
PRECISE REPRODUCTION OF SURFACES The instructions in this document use example files available from the Geomagic web site. To obtain the examples, download the data files from the web page on which you found this Guide to a directory of your choice. Double-click it to extract the example files that are referenced in this Guide, then start Geomagic Studio 12. It is possible to open the first file, follow the instructions carefully, and complete a workflow without opening another file. But each section also mentions a specific file name that provides a new starting point. For example, the result o f steps applied to HandlePointPhase.wrp in Step 1 can be checked by opening HandlePolygonPhase.wrp.
2.1 Point Phase The Point Phase procedure explains how to register and merge two point objects into a single object, and represent that object as a polygon object. The typical way to begin is to obtain one or more Point objects, either by c reating them with a scanner plugin or by opening an existing Point object file. These steps are common to both workflows described in this document.
Step 1. Use Application Button > Open to open HandlePointPhase.wrp in Geomagic Studio 12. This object contains two scans: Underside and Topside. (Note: The Application Button is the Swirl icon in the top-left corner of Studio.)
Step 2. Select the Underside scan in the Model Manager and press F2 to hide all other objects. Use one of the selection tools from the right-hand menu to highlight the points (in red) that belonged to the tabletop. Press the Delete key to delete these points.
Step 3. Select the Underside and Topside scans in t he Model Manager. These objects contain extraneous data points. From the Points tab, click Reduce Noise. Select “Prismatic Shapes (aggressive)” as the Noise Reduction type. To perform the reduction, click Apply and then OK.
Step 4. Navigate to the Alignment tab, highlight both objects in the Model Manager, and click on Manual Registration to achieve a rough registration of the two halves. Pick “Topside” as the Fixed object, and “Underside” as the Floating object. Use n-Point Registration and pick at least three points on the Fixed and the same three points on the Floating, then press Register and OK. The parts become aligned.
Step 5. Stay on the Alignment tab and click on Global Registration to “fine-tune” the alignment between the two halves . After you press Apply and OK, the halves are well registered but remain as separate objects (as shown to the right). At this stage, the o bject appears to be a smooth surface —increasing the magnification on the object still reveals the points.
Step 6. Select Group 1 in the Model Manager, navigate to t he Points tab, and click on Combine Point Objects to create a single point object that represents the whole door handle. When prompted, name the single object “Whole Handle.” Click Apply and OK. Step 7. Click on the Uniform Sample icon from the Points tab to create an evenly dense point cloud. Accept the default settings, then press Apply and OK. Step 8. Create a polygon object by clicking on the Wrap icon. Set the Max Triangles to 220,000, and set Noise Reduction to Medium. (This noise reduction supplements the reduction performed earlier.) Move the Sampling slider bar all the way to the right to Quality. To minimize the amount of data in the Model Manager, uncheck “Keep Original Data.” Click OK.
The Point Phase is now complete. The object has become a Polygon object.
2.2
Polygon Phase
The steps in the Polygon Phase walk you through cleaning up the polygon object in preparation for moving to the Surface Phase or for exporting specialized outputs.
Step 1. Open HandlePolygonPhase.wrp, and Navigate to the Polygons tab and click on the Fill Single icon in the Fill Holes box. For best results, start by filling the largest hole individually by clicking the Flat fill type (see picture to right) and clicking on its border. Press the ESC key or click again on the Fill Single icon to exit the Fill Single mode.
Step 2. All remaining holes, even tiny and unnoticeable ones, can be filled simultaneously by pressing Fill All with Curvature-Based filling type. Step 3. Use Mesh Doctor to “clean up” the polygon model further. Press Apply to run the command. and select the rough area on the door Step 4. Still in Mesh Doctor, click the Defeature icon handle (like in the picture below). Click Apply to delete the selected triangles and fill the resulting hole. Press CTRL+C to clear the selection.
Step 5. Within Mesh Doctor, click on Make Manifold sides.
to force all triangles to be connected on all
The object is now a highly refined Polygon object that is ready to be t aken to one of the Surface Phases (Exact Surfaces Phase or Parametric Surfaces Phase) or to be exported using one of the optional output steps.
2.2.1 Optional Output Steps Most of the time, the workflow will continue on to one of t he Surface Phases. However, you can choose to export the as-is polygon object as a .stl or .obj file or you can choose to export a section from t he polygon object.
2.2.1.1 Saving the Polygon Object for use by Other Apps Many external software packages accept a .stl or .obj representation of a polygon object. To create one now, right-click on the WholeHandle polygon object in the Model Manager and select Save. Save the object as a .stl or .obj.
2.2.1.2 Exporting a Profile from a Polygon Object A two-dimensional section of the Polygon object can also be exported now so that a 3D solid can be reconstructed in an external CAD system. This is a common “side usage” of Geomagic Studio.
Step 1. Navigate to the Curves tab and click Create by Section. Pressing Apply and OK generates a Curves object in the Model Manager. Step 2. Right-click on the curves object in the Model Manager and save it with a file type of .obj or .igs.
2.2.2 Choosing the Next Phase Once the Polygon Phase has been completed, the next step is to move to either the Exact Surfaces Phase or Parametric Surfacing Phase. This Guide describes two paths through the Exact Surfaces Phase.
Step 1. Open ExactSurfacesPhase.wrp and select the Exact Surfaces tab. Click the Start Exact Surfacing icon on the left side of the ribbon toolbar.
Producing a “good” surface during Exact Surfacing Phase requires creating an object with a good patch structure with regularly shaped patches (i.e., rectangular shaped without severe or multiple-curvature changes) that fill spaces efficiently.
The basic steps for Exact Surfaces Phase are illustrated in the flowchart on the next page. The first column depicts steps to produce a precise reproduction of an object with the emphasis on curved regions. The second set of steps places no emphasis on curved regions. • For the “Exact Surfaces Phase with Emphasis on Curved Regions,” start at section 2.3.1. • For the “Exact Surfaces Phase Legacy Workflow,” start at section 2.3.2. • For using AutoSurface to automatically work through either of the above two workflows, start at section 2.3.3. Note: AutoSurface may not be suitable for all models, so it is a good idea to understand the full Exact Surfaces Workflow.
2.3 Exact Surfaces Phase 2.3.1 Exact Surfaces Phase with Emphasis on Curved Regions The steps in this section produce a precise reproduction of the original object with emphasis on the precision of the curvy parts.
Step 1. Click on Contours > Detect Contours.
Press the Compute button. The red separator bands represent the software’s estimate of the location of curved regions. Use the Paintbrush Selection tool to add (with LMB) and remove (with CTRL+LMB) the separators so that they appear as pictured in the third figure below —the goal being to put red separator bands where you would expect to see seams on an upholstered chair. Check the Detect Extension Contours checkbox, set the Sensitivity to the highest, and press the Extract button to generate yellow contour lines. Click OK to exit the command.
At this point, yellow contour lines are present on the centerlines of the estimated curved regions.
Step 2. Now we want to edit the contour lines so that they lie on the center of the curved areas. Click on Edit Contours. Click Subdivide and then Accept. The Operation icons will become active. Check the box for Curvature Map to see a visualization of the curved regions. Use the Draw operation to click and drag the subdivision points (if needed) to the center of the rounded areas. Click the Check Problems button to check for any bad intersections. Use the arrow buttons below to scroll through any problems that are flagged. Note: It is very important to remove all problems before moving on! When the problems have been resolved, click OK to exit.
Step 3. Now that yellow contour lines appear on the centerlines of estimated curved regions, the “estimated” locations of c urved regions need to be converted into “actual” locations of curved regions. Click on Subdivide/Extend Contours to lay “contour patches” on the curved regions. Select the Extension radio button. Click Extend and OK. Contoured patches define where the surface will be reproduced with the greatest precision.
Step 4. Click on Shuffle Panels. Use the Fill Empty Panels button to fill the spaces between the contour patches. Press OK.
Dealing with Bad Patches The command in Step 3 sometimes generates tangled patch lines, but you might not know until a warning is issued in Step 4. Therefore, it is good practice to examine the object when Fill Empty Panels is complete. If bad patch lines are found, use the Move Vertices mode of Repair Patches. Simply left-click and drag green vertices until the patch lines ar e untangled.
Before After
Step 5. Click on Construct Grids. Press Apply. If the resulting grids are tangled and highlighted red, reduce the Resolution to about 17 and try again. Press OK. The grids serve as a “bed” for the NURBS surface that will be generated in the next step.
Before Construct Grids (left) and after (right)
Step 6. Click on Fit Surfaces. Accept the default settings, then press Apply and OK. The olive green NURBS surface has now been applied to the model, and can be exported as .igs or .stp. Step 7. Click on Convert > To CAD Phase. Click Yes on the popup message that appears.
Step 8. Save the gold-colored CAD object as .igs or .stp for further processing by an external system, such as a CAD package. The “Exact Surfaces Phase with emphasis on curved regions” objective is complete.
2.3.2 Exact Surfaces Phase with Legacy Workflow The steps in this section produce a precise reproduction of the original object with no particular emphasis on curved regions.
Step 1. With HandleExactSurfacesPhase.wrp, select the Exact Surfaces tab. Click the Start Exact Surfacing icon on the left side of the ribbon toolbar. Step 2. Click on Detect > Detect Curvature. Under Granularity, Set the Target to 500 curvature lines and Curvature Level to 0.25. Click Apply and OK. The resulting black lines represent candidates for promotion to orange panel demarcation lines in the next step.
to achieve an optimal set of orange Step 3. In the Contours group, click on Shuffle Curvature Lines panel demarcation lines. “Optimal” orange lines resemble the seams on a furniture slip -cover. The art of shuffling curvature lines is to convert certain black lines to orange so that the resulting set of orange lines resembles the seams on a slip-cover. In other words, the orange lines to outline the curved areas. • In Promote/Demote Lines mode, promote some black lines to orange by clicking them with the LMB (and Ctrl+LMB to make orange lines black, or “demote”). • In Flip Path mode, change the direction of existing black lines so they become more likely candidates for promotion to orange.
When complete, press OK.
Before Shuffle Curvature Lines (left) and after (right)
Step 4. Click on Construct Patches. Select the Specify Patch count radio button. Specify the Target Patch Count to 100. Click Apply and OK. Step 5. Use Shuffle Panels to make the patches more orderly.
Before Shuffle Panels (left) and after (right) The figures below are close-ups of a panel during the Shuffle Panels command. Figure A is of the panel after clicking it to activate it for subsequent actions. Figure B is of the panel after clicking the left end in Add/Del 2 Paths mode. Note that each pair of opposing sides now has an equal number of “path” lines (even though they are tangled). Figure C is of the panel after setting the Type to “Grid” and pressing Execute.
The goal is to make all panels more orderly by this technique.
Step 6. Click on Construct Grids and enter in a Resolution of 20. The grids serve as a “bed” for t he NURBS surface that will be generated in the next step. Click Apply and then OK.
Before Construct Grids (left) and after (right)
Step 7. Click on Fit Surfaces. Select the Adaptive fitting radio button. Click Apply and then OK. This olive green model can be exported as .igs or .stp. Step 8. Optionally, click on Convert > To CAD Object. Click Yes on the popup message that appears.
Step 9. Save the CAD object as .igs or .stp for further processing by an external system. This object is an accurate reproduction of the scanned data. The Exact Surfaces Phase Legacy Workflow is complete.
2.3.3 Exact Surfaces Phase with AutoSurface The steps in this section produce a precise reproduction of the original object automatically with one of two workflows (emphasis on contours or curves).
Step 1. Open With HandleExactSurfacesPhase.wrp, select the Exact Surfaces tab. Click the Start Exact Surfacing icon on the left side of the ribbon toolbar. Click on AutoSurface.
Step 2. Select the Mechanical radio button and leave all the other settings as default. Notice that Interactive mode is checked. Click Apply. It will run through 8 phases of surfacing. Step 3. Interactive mode allows the user to stop and fix some problems manually before continuing at certain stages. An error like below may occur.
Click Yes. Use the Arrow Keys under Walkthrough to click through the problems. Fix any patch problems using the tools under Action. Click Update to check to see if a problem has been fixed. Tip: Avoid sharp or wide angles when editing the patches. Think of it as trying to make the patches as rectangular/square as possible.
When no problems remain, click Done to continue AutoSurface. The command will complete surfacing to create a NURBS model. Click OK to exit. This olive green model can be exported as .igs or .stp.
Step 4. Optionally, click on Convert > To CAD Object. Click Yes on the popup message that appears.
Step 5. Save the CAD object as .igs or .stp for further processing by an external system. This object is an accurate reproduction of the scanned data.
