The shape of a NURBS is controlled by its points, sometimes also called control points or control vertices (CVs). The points define segments and the segments are joined at knots.
In a linear curve, the segments are straight lines between the control points and the control points and knots overlap exactly.
In a cubic curve, the segments are interpolated between control points and the knots lie on the curve.
| A |
Points control the shape |
| B |
Segments interpolate between points. |
| C |
Knots are where the segments join. |
In a surface, the segments form knot curves in two directions (knot curves are sometimes called isoparams or isoparms). The knot curves intersect at the knots, forming four-sided patches.
