Geometric characteristics:
The NURBS curve shall exhibit the following geometric characteristics:
- Bezier & non-rational b-spline curves are special cases.
- Local Approximation : If a control point is moved or a weight is altered, it shall influence the curve only in p = 1 knot spans.
- Strong Convex Hull Property: If u ∉ [ui , ui +1 ] , then C (u) lies in the convex bull of Pi - p, . . . , Pi.
- Invariance under affine & perspective transformations.
- The similar differentiability property as with the basic functions.
- If a specific weight is set to zero, then the equivalent control point has no influence at all on the curve.
If wi → + ∞,
then
NURBS surfaces might be analyzed similarly utilizing the bivariate rational basis functions