INTERACTIVE USER GUIDE

Parametric Surfacing for the Restoration of Intended Design

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Guide History

Date Revision Aug 2009 First Release May 2010 Updates for Geomagic Studio 12

About Geomagic Inc.

Geomagic, Inc. is a worldwide software and services company headquartered in Research Triangle Park, 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.

Contact Information

Geomagic, Inc. P.O. Box 12219 Research Triangle Park, NC 27709 USA Phone: +1 (800) 251-551 or +1 (919) 474-0122 Fax: +1 (919) 474-0216

Web Sites Geomagic, Inc. http://www.geomagic.com Technical Support http://support.geomagic.com Training http://training.geomagic.com

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Table of Contents

1 GUIDE DESCRIPTION 5

1.1 Introduction 5

2 RESTORATION OF INTENDED DESIGN 6

2.1 Procedure 6

2.1.1 Point Phase and Polygon Phase 6 2.1.2 Parametric Surfaces Phase 11

1 GUIDE DESCRIPTION

This Guide leads an advanced beginner through a fundamental workflow of Geomagic Studio 12 -- that of discovering the design intent of an imperfect part, or of a near-perfect part that is scanned imperfectly, and generating a CAD object with perfect geometry.

The Guide requires Geomagic Studio 12 with the Capture, Wrap, Shape, and Parametric Surfaces module licenses.

This plumb bob will be surfaced with a set of geometrically perfect planes and cones.

1.1 Introduction

“Restoration of intended design” means that surfaces are replaced with geometrically perfect CAD faces. For example, planar surfaces are replaced with perfectly planar CAD faces, and cone-like surfaces are replaced with perfectly conical CAD faces.

This workflow starts with two reasonably clean point objects, one that represents the front (or “forward”) section of the bob, and one that represents the back (or “aft”) portion of the bob. The process continues with conversion of the Point objects to Polygon objects, consolidation of the two objects into one, further refinement of the single polygon object, and detection of basic geometric shapes so they can be rendered as perfectly geometrical CAD faces.

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 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 a solution involving the Point, Polygon, and Parametric Surfaces Phases.

• CAD Phase: the state of an object when it is ready to be exported to a CAD package.

2 RESTORATION OF INTENDED DESIGN

The instructions in this document use example fi les available from the Geomagic web site. To obtain the examples, download the data fi les 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. However, each step also mentions a specific file name that provides a new starting point. For example, the result of steps applied to BobPointPhase.wrp in Step 1 can be checked by opening BobAfterManualReg.wrp.

2.1 Procedure

2.1.1 Point Phase and Polygon Phase

This procedure starts with two clean point objects contained in a single .wrp fi le. The two objects are wrapped to form polygon objects. A remnant of the scanning fixture is removed, then the two halves are registered and combined to form a single polygon object. Voids in the mesh are filled, and an undesirable feature is removed. Areas of high curvature are delineated, thus separating regions that are near-perfect planes and cones. The near-perfect shapes are rendered with perfect geometry and a CAD object is generated from the set of perfect planes and cones.

Step 1. Use Application Button > Open to open BobPointPhase.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.)

This object contains two clean scans: the forward and aft portions of a plumb bob.

Step 2. Highlight Bob1 in the Model Manager.

From the Points tab, click on the Wrap icon. Accept the defaults, but do not check Keep Original Data, and press OK.

Step 3. Repeat Step 2 for Bob2.

The result is that both portions of the plumb bob are converted to Polygon objects. Notice that the Model Manager now contains Polygon objects instead of Point objects. (The objects moved from the “Point Phase” to the “Polygon Phase”.)

Step 4. Notice that Bob1 contains extra data (part of the fixture to which it was clamped during data capture). This is a common condition. In this case, set the selection tool to behave like the Lasso Tool by choosing it from the right-hand menu.

Also, pick Select Through from the right-hand menu or press Ctrl+G (which causes sets of triangles to be selected “all the way through”, not just the visible or front triangles). Highlight the extra data and press the Delete key.

Step 5. The next goal is to join each portion of the bob into a single object. Select both Bob1 and Bob2 in the Model Manager so that both are highlighted simultaneously.

Navigate to the Alignment tab and click on Manual Registration. In the Mode group, select the 1-Point Registration radio button.

In the Fixed list, click Bob1. In the Floating list, click Bob2.

The plan is to click one point on Bob1 (the Fixed) and one point on Bob2 (the Floating) and pull them to a single point in space. The two halves will look like a single, registered object.

Rotate both objects such that

they have similar orientations.

Click a point on the Fixed object.

Click a point on the Floating

object that lies at the same

position as the one clicked

on the Fixed object.

Immediately, the lower panel displays the Fixed and Floating objects after they are registered at to the point that was clicked.

Click on Register to improve the alignment. Click OK. Notice that Bob1 and Bob2 have been grouped into Group 1 in the Model Manager.

Step 6. Open BobAfterManualReg.wrp.

The registered halves of the object are positioned in space to look like a single object. The next step is to convert the registered halves into a single polygon object. Highlight Group1 in the Model Manager, navigate to the Polygons tab, and click on Merge. Check the Global Registration checkbox, which “fine-tunes” the registration done with Manual Registration. Click OK.

The previous command created an object named Merged. Right-click on the name in the Model Manager and select Rename. Type in PlumbBob and press Enter.

Click

Step 7. There are still two holes in the polygon mesh. Click Fill All to construct a polygon mesh where holes exist.

Select the Flat Fill type, click Apply and then click OK.

Step 8. For the purposes of this Guide, the threaded hole at the end of the plumb bob does not have to be reproduced. In fact, objects often have structures that users prefer to ignore. This step demonstrates a technique for removing a hole and replacing it with a plane.

Orient the bob as in the illustration at right, and select the Custom Region Tool from the right-hand menu (or use the shortcut Ctrl+U). Click a series of points around the hole like in the illustration, and press the Space bar to automatically complete the circle when it is close to completion.

When the loop becomes complete, everything inside the loop becomes selected, including all polygons inside the hole.

Press Delete. The selected polygons disappear.

The next step is to fill in the opening. Click Fill All to construct a polygon mesh where holes exist. Select the Flat Fill type, click Apply and then click OK.

Step 9. Before moving on to Parametric Surfacing, it’s always wise to use the Mesh Doctor. It optimizes the polygon mesh to avoid problems ahead. Under the Polygons tab, click on Mesh Doctor. Accept the defaults, click Apply to fix any outstanding errors, and then click OK. Next is the Parametric Surfacing Phase for surfacing according to the probable design intent. For example, shapes that approximate planes will be turned into perfect planes, and surfaces that approximate cones will be turned into perfect cones.

2.1.1 Parametric Surfaces Phase Step 10. Open BobParametricSurfaces.wrp and select the Parametric Surfaces tab. Click the Start Parametric Surfacing icon on the left side of the ribbon toolbar.

Step 11. Click on Detect Regions. Accept the defaults and press Compute. The goal is to generate a red separator band on areas of relatively high curvature, and thus “segment” the object into a set of relatively flat areas.

Tip: With the default settings, one of the contours failed to be recognized, so set Curvature Sensitivity up to 75. This object has an element that is small but distinct, namely the beveled shoulder, so set Minimum Area to the lowest setting (0.26). Click Compute again.

The result of the Detect Regions command can often be improved by hand. In this case, a planar region was accidentally recognized as two adjoining planes.

In the Editing group, press the Merge Regions icon. Click in one of the planes, drag across the extra red separator, and release the mouse button. The two regions become one. Note: If you wish to merge other sections, the Merge Regions icon must be pressed each time.

Any other problems can be fixed by using any of the Selection Tools from the right-hand menu. For instance, the beveled edge should be defined as one region instead of six separate ones. Hold down the CTRL key and use the Paintbrush Tool to remove some of the separators like in the picture below. If you delete too much, use CTRL+Z to undo or redraw them with the Paintbrush Tool.

Repeat that technique to join all the beveled regions into a single beveled region like in the third picture above.

Under Contours portion of the dialog, click Extract. The regions have now been defined. Click OK. Notice that the Regions have changed colors indicating the classification of the region. This will be explained in later steps.

Step 13. Open BobAfterDetectRegions.wrp. Click on Edit Contours. For this model, the contours do not need to be edited, but for good practice, check the box for Curvature Map, and take a closer look at the contour lines. Make sure that they follow the curvature appropriately. Click the Check Problems button to check for any possible contour issues. If there are no problems, click OK.

Step 14. Notice the colors of the regions. These indicate a type of surface classification (i.e. plane, cylinder, freeform, etc.). Light green is the color for planes. Notice that AutoClassify sometimes mis-judges the shape of a region. In the picture below, Studio thinks that the salmon colored region is a freeform because of the rough underlying data.

Click on the mis-classified region like in the picture below and go to Classify Regions>Plane. The region will now be light green like the rest of the planes on the PlumbBob.

Repeat this action for the beveled edge, which should be a light blue cone like the nose region.

Every region is now correctly assigned a basic geometric shape, so the next step is to calculate a perfect geometric surface for each geometric shape.

Step15. Press CTRL+A to highlight all of the primary regions. Click Fit Surfaces and then click Apply to apply surfaces to each of the regions. Blue surfaces indicate that the surface fit well. Orange (warnings) and red (errors) surfaces indicate problems fitting the regions.

All of the regions except the nose fit as expected. Notice the orange color of the nose surface.

Expand Diagnostics in the dialog and check Error Labels. The warning is High Boundary Deviation. At this point, we can choose to accept the proposed warning surface by clicking Accept (in which case it will turn blue), or we can edit the profile of the surface. In this case we are going to edit the profile.

Click OK. A message will appear indicating that warnings remain and that Repair Surfaces can be used for further instruction. Click OK.

Click on Repair Surfaces. Expand the High Boundary Deviation warning message under Problems and Click on the name of the surface. A color deviation plot will appear. Click the What’s Wrong button. A popup will appear indicating what the problem is with the surface and proposes how to fix it. In this case, we will accept the proposed surface by clicking Accept. Click OK.

Tip: Now that the primary regions are fitted with surfaces, this is the ideal time to use Parametric Exchange for the transfer of surfaces directly to one of four CAD packages (Inventor, SolidWorks, CATIA, or Pro/Engineer). The beauty of Parametric Exchange is the real-time, parametric transfer of surfaces to a CAD package without the necessity to finish the steps in this Guide! Download the Parametric Exchange User Guide for a guide to using this tool.

Step 16. Now it is time to fit the connections in between the primary regions. Highlight the straight connections that go around the model. Go to Classify Connections>Constant Radius to make them blue. Set the rest of the connections as Freeform (yellow).

Press CTRL+A to highlight all connections and click on Fit Connections. Click Apply.

An error such as Intersecting Trim Curves may appear. Click OK.

In this case, the connection lines need to be adjusted so that they aren’t intersecting. Click on Repair Surfaces. Click on the name of the connection with the error under Problems and click on Fix.

Expand Edit Boundaries and zoom into the problem areas. Manually click and drag the boundary lines so that they are not criss-crossing like in the picture below. Click Apply and then Done. The error no longer exists under Problems. Click OK.

Step 17. Perfected surfaces have been generated, so it’s time to render perfected CAD faces. Click on Trim and Stitch. This is the step that converts generated surfaces into CAD faces. Select the type of CAD object that you would like to create (see below for explainations).

A Stitched Object is a water-tight representation of CAD faces that represent the object.

Untrimmed Primaries is a set of primary surfaces, with-out connection surfaces --suitable for export to a CAD package for the creation of custom connections.

Trimmed Primaries is a set of primary surfaces without the connectors, also suit-able for export to a CAD package for further work.

For the purposes of this Guide, select the Stitched Object radio button, and press the Apply button. Click OK. This

creates a stitched CAD object in the Model Manager.

Step 16. Open BobCADPhase.wrp

Note that PlumBob – Stitched Model exists in the Model

Manager. To export it to a CAD package for further work,

highlight it in the Model Manager, right-click and pick

Save…, then set Save As Type to .IGES or .STEP.