Graphics Programs Reference
In-Depth Information
•
Control Vertices Count
: In this option, we control the number of control
vertices in U and V directions.
•
Degree
: In this option, we control the surface degree in U and V direc-
tions.
•
Options
: Deleting original geometry does not maintain the original sur-
face when sorting the command. If the original surface is trimmed (
Retrim
previously trimmed surface
), this option maintains the trim on the new
surface.
Exercise 12.3
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 ac-
tivated.
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 sur-
face. There are only four control points at the corners of the bounding
rectangle.
7. The
CVREBUILD
command allows you to increase control points and de-
gree. Define six control vertices in each direction.
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