Interpolated NURBS surfaces
As described in Creating NURBS curves, NURBS curves can be created by interpolation points or control points. Similarly, a NURBS surface can be created by interpolation points. An interpolated surface is a NURBS surface that passes through a two-dimensional array of 3D interpolation points. Regular NURBS surfaces are defined by their control points, which may not lie on the surface and can be difficult to use for reshaping the surface (it is difficult to know how much the control point should be moved in order to reshape the surface by a specific distance). Because interpolation points lie on the surface, it is much easier to modify these points with the Reshape tool or the Object Info palette, and have the surface pass through the points.
An interpolated surface can be created, or an existing untrimmed NURBS surface can be converted to an interpolated surface, for easier reshaping.
When an interpolated surface is used in another operation, such as a Boolean operation or trimming, the surface becomes a control point surface.
Creating an interpolated surface
|
Command |
Path |
|
Create Interpolated Surface |
Model > 3D Power Pack |
A new interpolated NURBS surface can be created with the Create Interpolated Surface command.
To create an interpolated surface:
Select the command.
Click to define the start of the interpolation point row, and then click again to define the end of the row. Click a third time to define the column of interpolation points.
The Create Interpolated Surface dialog box opens.
Specify the number of interpolation points and degree of flexibility to create for both the U and V direction.
Click to show/hide the parameters.Click to show/hide the parameters.
|
Parameter |
Description |
|
U Direction |
|
|
Number of Points |
Specifies the number of interpolation points (up to 1000) to create in the U direction; this number must be greater than the U degree number |
|
Degree |
Indicates the flexibility of the surface in the U direction, from 1 to 28; a larger number results in a more variable surface |
|
V Direction |
|
|
Number of Points |
Specifies the number of interpolation points (up to 1000) to create in the V direction; this number must be greater than the V degree number |
|
Degree |
Indicates the flexibility of the surface in the V direction, from 1 to 28; a larger number results in a more variable surface |
Select Show Vertices from the Object Info palette to display the interpolation points. Use the Reshape tool to reshape the interpolated NURBS surface.
