NURBS curves are Shape objects, and you can use them as you do splines. You can use the Extrude or Lathe modifiers to generate a 3D surface based on a NURBS
curve. You can use NURBS curves as 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 Constraint and Path Deform paths or as motion trajectories.
You can assign thickness to a NURBS curve so it renders as a cylindrical object. (The thickened curve renders as a polygonal
mesh, not as a NURBS surface.)
A curve and the same curve rendered with thickness
There are two kinds of NURBS curve objects:
Like other Shape objects, NURBS curves can contain multiple sub-objects, which are either dependent or independent.
Creating Curve Sub-Objects
Creating Surface Sub-Objects
Creating and Editing Point Sub-Objects
Common Sub-Object Controls
Editing Point Sub-Objects
Editing Curve CV Sub-Objects
Editing Surface CV Sub-Objects
Editing Curve Sub-Objects
Editing Surface Sub-Objects
Like an object-level NURBS surface
, an object-level NURBS curve is a top-level NURBS model
that can contain NURBS curve, NURBS surface, and NURBS point sub-objects. A NURBS curve remains a Shape object unless you
add a surface sub-object to it; if you do, it converts to a NURBS surface (without changing its name).
Creating Independent Surfaces from NURBS Curve Objects
You can also create NURBS curve sub-objects by attaching or importing other objects such as other NURBS curves or spline shapes.
Attaching and Importing 3ds Max Objects
Display Controls for NURBS Models
Both NURBS curves and NURBS surfaces have a Display area in the Modify panel. These controls affect which portions of the
NURBS geometry are displayed. Next to the Display area is the button that turns on the toolbox for creating sub-objects.
- Point Curve
Point curves are NURBS curves whose points are constrained to lie on the curve.
- CV Curve
CV curves are NURBS curves controlled by control vertices (CVs). The CVs don't lie on the curve. They define a control lattice that encloses the curve. Each CV has a weight that you can adjust to change the curve.