Although NURBS curves are analytically generated, in order to generate and display them they must be approximated by line segments.
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Modify panel > Select a top-level NURBS object. > Curve Approximation rollout
Curve approximation controls are displayed in the creation parameters for curve objects, and on a Curve Approximation rollout for NURBS models (top-level NURBS objects). At the model level, approximation controls affect all curve sub-objects in the model.
Curve approximation is accomplished by segments. One or more line segments, or steps, are used to approximate each segment of the curve. For point curves, a segment of a curve is the portion between one point and the next. For CV curves, the segment is determined by the CV’s parametric knot. The transition from one CV curve segment to another isn’t visible in viewports.
Curve approximation parameters aren't animatable.
Interface
- Steps
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The maximum number of line segments used to approximate each curve segment. If the curve displays or renders with angles, increase this value. This control is unavailable when Adaptive is on. Range=1 to 100.
- Optimize
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Turn on this checkbox to optimize the curve. When on, interpolation uses the specified Steps value unless two segments are collinear, in which case they are converted to a single segment. This control is unavailable when Adaptive is on.
- Adaptive
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(The default.) Segments the curve adaptively, based on its curvature. In other words, the curve is assigned more segments where its curvature is greatest, and fewer segments where its curvature is less.