Geomagic系列教程 曲面的建立

Studio TutorialSurface Creation - FenderObjective:Learn how to create a NURBS surface on a polygonal model and perform some basic editing to reorganize the patch layout.Files:\…\Geomagic Studio 6\TutorialData\rear_fender.wrp1. Open rear_fender.wrp.This is scan data of a car fender containing about 80,000polygons.2.Change to the Front View. Use Ctrl+D to fit the view to screen.3.Before creating patch boundaries, it is recommended that the user first defineentities called Contour Lines, which can be specified manually or detectedautomatically by the software based on the model’s curvature. Contour Lines areused to guide the construction of surface patches and allow for easy editing andorganization of the patch layout.4. Select Detect Curvature from the Patches menu. This function will automaticallyhighlight Contour Lines on the model based on surface curvature.5. Toggle on the Auto Estimate checkbox. This will allow the software to estimate howcomplex the curvature is on this model and display the necessary number of contourlines.6. Leave the Curvature Level set to the default of 0.3 and toggle on the SimplifyContour Lines checkbox. Click Apply.7.The orange line that appears among the black lines represents the line of highestcurvature on the model. This orange contour line is used to guide the softwareduring the next step, which is the automatic construction of rectangular surfacepatches.8. Click OK to exit the command. We will now manually select some of the black linesto turn them into additional contour lines, which will also help organize the patch layout when we get to the Construct Patches command in a few more steps.9. Select Promote/Constrain from the Patches menu. Start by left-clicking the blackentities shown below to promote them to orange contour lines. You model should resemble the image at right when complete. If you accidentally promote a line you did not want, hold down Ctrl and click on the line to demote it.10.Contour Lines are most effective when they form closed loops or start and end at theedge of the polygon model, as shown in the example at right, below. They helporganize the patch layout and result in a higher quality surface. A set of Contour Lines like the one shown below at left do not adequately define the features of the model or create closed loops and are therefore not very useful.Bad set of Contour Lines Good Set of Contour Lines11. Click OK to dismiss the dialog. You should now have a model divided into fivepanels, or regions bordered by contour lines. This will cause the software toconstruct boundaries within these panels.12. Select Construct Patches from the Patches menu. Again toggle on the AutoEstimate checkbox. This allows the software to determine approximately how many surface patches are needed to cover the surface of the polygon model.13. Toggle on Optimize Vertex Degree and click Apply. This function will automaticallyplace approximately 90 four-sided surface patches on the polygonalsurface…something no other software can do! And you can tell the software to place any number of patches on the surface, from 1 to 10,000!14.Notice the well-ordered nature of the patch layout. This is the benefit of usingcontour lines to define panels before using Construct Patches. At this point, the usercould complete the NURBS surfacing in two more easy steps. However, we will use this model to practice some basic editing of the patch layout first.15. Select Shuffle Panels from the Patches menu. Since our contour lines form closedregions, we can easily reshuffle them to create a more organized patch layout.16.Click anywhere on the large panel indicated below. When highlighted in white, clickthe four corners shown. Small red circles will appear after clicking each corner.¾ Quick Tip: It is best to zoom in and click just inside the panel when selecting the corners. This helps guarantee you have selected the right one17.After all four corners are picked, the model will appear as shown above. Thenumbers in red and green indicate the number of patches along each edge of the panel. When the numbers are green that means the number on the opposing side is the same, or balanced. When the numbers are red, they are different, orunbalanced. In order to shuffle this panel, opposing numbers must match. When both pairs of numbers match, the panel is balanced and can be automaticallyreorganized as an array, or grid, of patches.18. Change the Mode to Add 2 Paths. Click 2 times near the edge shown below tomake each side have 12 paths and balance the panel. You should have 4 paths on the short sides and 12 on the long sides of this panel.¾ Quick Tip:If you select the wrong path or corner, hit Ctrl+Z to undo the last pick.19.After adding the paths, both number pairs are balanced and colored green. Thismeans it is ready to be reshuffled. First, change the Type to Grid, if it is not already, which best describes this panel type. Then click Execute. The panel is reorganized in an orderly, grid-like fashion, as seen below. Note that with Auto Distributetoggled on, the vertices are also evenly distributed along each side when you click Execute.20. Click Next to shuffle another panel. Click on the long, skinny panel shown below andrepeat the process of defining corners, adding paths and distributing vertices toachieve the layout shown (2x2, 12x12). This time however, change the Type toStrip, since the Strip type is better suited for narrow, curving panels. Click Execute when the panel is balanced. It should appear as below.21.When satisfied with the layout, click Next to accept the changes and move to thenext panel.22.Continue making changes to the three smaller panels shown below until you havethe patch layout shown.23.When finished, click OK to exit the dialog.24.To straighten out a contour line that may be crooked, we can use tools like FitContour Line, which allow selective editing of contour lines.From the Patchesmenu, select Fit Contour Line.25.Select one of the contour lines, such as the one in the image below. Whenhighlighted, change the number of Control Points to 2. Hit Enter on your keyboard and a preview of the new fitting will be shown. Now click Execute to straighten the line. Results should appear as below, at right.26. Click OK to exit the command.27.You can also move individual vertices around manually. From the Patches menu,select Edit Patches.28.In the dialog, use the default setting, which is Move Vertices, and beginexperimenting with moving some of the control point vertices around by left-clicking one of the green points and dragging it to a new position. Notice that points always project onto the polygon surface. It is impossible to pull them off.29.Continue moving a few points around to get a feel for how easy it is to moveindividual vertices. This is one of the most useful editing tools in Shape Phase.30. Click OK when satisfied that you understand the function.31.It is easy to make changes to a well-ordered patch layout. We can, for example,quickly add or remove rows of patches in order to achieve our desired surfacequality.32. From the Patches menu, select Zip Patch Layers. Click on the line indicated below.A row of patches will become highlighted in white. Click Execute and that row ofpatches is removed, or “zipped”.33.Switch to the Unzip option. Click on the line indicated below. That row of patcheswill become highlighted in white. Click Execute. The selected row of patches is subdivided, or “unzipped”.34. Select OK to exit the dialog. This technique can be very useful if you require higheraccuracy on a particular portion of the model. Simply add one or two new rows of patches to achieve greater definition of the geometry.35. Click the Relax Contour Lines icon on the toolbar. This will help straighten out theContour Lines.36. Click the Relax Boundaries Linear icon, also on the toolbar. This helps evenlyspace the boundaries.37. Select Construct Grids from the Grids menu. Set the Resolution to 20 and clickOK. This operation places a U-V grid network inside each patch. The control points for our NURBS surface will follow these grids.¾ Quick Tip: The range for number of grids is 8-100. The higher the number, the more accurate the surface will be. Conversely, a lower number will tend to yielda smoother surface. A grid count between 20 and 50 is usually optimal. Thisvalue will not affect the file size of the final IGES file.38. Select Fit Surfaces from the NURBS menu. Set the Control Points value to 12 andthe Tension value to 0.25. Click OK. This operation automatically fits a C1continuous NURBS surface onto the grid network. Our surface is complete!39.To export an IGES or STEP surface, simply go to FileÆSave As and specify IGESor STEP as the type to save as.NOTE: IGES and STEP export are not possible with Evaluation versions ofGeomagic Studio. Contact your local Raindrop Geomagic representative if you wish to obtain the fully functional version, which allows the user to save in a wide variety of formats.End of Tutorial。