We are going to create a NURBS surface to simulate a circular terrain:
1. Start a new drawing.
2. Create a circle with 40 units radius.
3. A layer, called Surface, with color at choice, should be created and
activated.
4. With the PLANESURF command and the
Object
option, a planar round surface
is created.
5. Applying the CONVTONURBS command, this surface is transformed into a
NURBS surface.
6. To display control points, apply the CVSHOW command and select the surface.
There are only four control points at the corners of the bounding rectangle.
7. The CVREBUILD command allows you to increase control points and degree.
Define six control vertices in each direction.
8. Now it is easy to model the surface. With
Polar
or
Ortho
turned on, move
control points up or down. To pick control points, it is better to use the
2D
wireframe
visual style.
9. Save the drawing with the name A3D_12_03final.DWG.