Creating and Modifying NURBS Surfaces

November 13, 2003 | Comments

Tutorial provided by Nemetschek North America
November 13, 2003

In this tutorial, you’ll create the body of a telephone handset to learn the basics of creating and modifying NURBS surfaces.



Setting Up the Modeling Units

This tutorial works in inches. To set up the units for modeling distances in inches:

1. Select Page > Units.

2. In the Units dialog box, select Inches from the Unit Name list. All distances entered for designs will now be in inches.

Creating a Block

3. Click the Rectangle tool  nurbs02[1]  from the 2D Tools palette and draw a 6”x1.5” rectangle.

4. Extrude the rectangle. With the rectangle selected, click Model > Extrude. In the Create Extrude dialog box, enter 1.5” for the Extrusion value. Click OK to create an extrude object.

Creating NURBS Surfaces

5. Convert the extrude object to NURBS surfaces using the Model > Convert to NURBS command, which creates a group of NURBS surfaces.

6. Select Organize > Ungroup to get six individual surfaces for the six faces of the extrusion. Deselect all the surfaces.

7. Change the view to front view by selecting View > Standard Views > Front. Draw a marquee box around the top surface to select it.



8. Change the view to right isometric by selecting View > Standard Views > Right Isometric. Make sure that the top surface is still selected.

9. Open the Object Info palette. At this point, the NURBS surface properties are as follows:


Reshaping the NURBS Surface

10. In the Object Info palette, change U Degree to 2 and V Degree to 2. The number of vertices of the selected NURBS surface should now be 9.

11. In either Edit U or Edit V, click on the arrow(s) until the vertex at the center of the top surface is selected.



12. From the Move pulldown list, select Vertex Only.

13. The Z value for the selected vertex is 1.5”. Change the Z value from 1.5” to 3”. The surface becomes dome shaped.



14. Change to front view by selecting View > Standard Views > Front. Deselect the top surface and draw a marquee box around the bottom surface to select it.

15. Reshape the bottom surface as described in steps 1 – 4. Change the Z value for the vertex at the middle of the bottom surface from 0 to 1.5”.

Creating the Solid

16. Select all the surfaces and add them together by selecting Model > Add Solids.



Smoothing the Edges

17. Click the Fillet Edge tool  nurbs8a[1]  from the 3D Tools palette. Open the Fillet Edge Preferences dialog box by clicking on the Preferences button in the Mode bar.


18. Enter 0.5” in the Radius field, and then click OK.

19. Press the Shift key and select the four vertical edges. Perform the blend by pressing Enter (Win) or Return (Mac) or click the check mark button on the Mode bar.



20. Open the Fillet Edge Preferences dialog box by clicking the Preferences button in the Mode bar. Select the Select Tangent Entities checkbox. Enter 0.4” in the Radius field, and then click OK.

21. Press the Shift key and select the tangential sequence of edges at the top and at the bottom. Press Enter (Win) or Return (Mac) or click the check mark button on the Mode bar to blend the selected edges.



22. To render the model, use the Light tool nurbs13[1]  from the 3D Tools palette to insert a light source, and then select View > Rendering > OpenGL.




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