NURBS Surface objects are the basis of NURBS models. The initial surface you create using the Create panel is a planar segment with points or CVs. It is meant simply as "raw material," an easy way to begin creating a NURBS model. Once you have created the initial surface, you can modify it in the Modify command panel by moving CVs or NURBS points, attaching other objects, creating sub-objects, and so on.
There are two kinds of NURBS surfaces:
You can also create a NURBS surface from a 3DS MAX geometric primitive.
Creating NURBS Surfaces from Geometric Primitives
NURBS surfaces can contain multiple sub-objects, including NURBS points, NURBS curves, and other NURBS surfaces. These sub-objects are either dependent or independent.
Creating and Editing Point Sub-Objects
Editing Point and CV Sub-Objects
You can also create NURBS surface sub-objects by attaching or importing other 3DS MAX objects.
Attaching and Importing 3D Studio MAX Objects
Both NURBS curves and NURBS surfaces have a Display area in their Modify panel. These controls affect which portions of the NURBS geometry 3DS MAX displays. Next to the Display area is the button that turns on the toolbox for creating sub-objects.
Display Controls for NURBS Models
Caution: When you move CV sub-objects, 3DS MAX must calculate the effect over a region of the surface. Although the calculations are optimized, this is a more involved process than simply moving vertices in an editable mesh. Because of this, if you manipulate large numbers of a NURBS surface's CVs -- by transforming, animating, applying modifiers, and so on -- you will notice a drop in interactive performance.