NURBS curves are Shape objects. The Extrude and Lathe modifiers can generate a 3D surface based on a NURBS curve. A NURBS curve can be the path or the shape of a Loft. (Lofts created using NURBS curves are loft objects, not NURBS objects.) You can also use NURBS curves as Path Controller paths or motion trajectories.
You can give a NURBS curve a thickness so it renders as a cylindrical object.
There are two kinds of NURBS curves:
Like other Shape objects, NURBS curves can contain multiple sub-objects. NURBS curve sub-objects are either NURBS curves or NURBS points. These sub-objects are either dependent or independent.
Creating and Editing Point Sub-Objects
Editing Point and CV Sub-Objects
Note: A NURBS model can include NURBS curve sub-objects. You create and edit these the same way you create object-level NURBS curves. The only difference is that NURBS curve sub-objects can’t have a renderable width.
You can turn a curve object into a surface either by using modifiers, or by using the Edit Stack button.
Creating Independent Surfaces from Curve Objects
You can also create NURBS curve sub-objects by attaching or importing other 3DS MAX objects such as other NURBS curves or spline shapes.
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