Modifying a knot of B-spline curves
The modification of a knot of a B-spline curve of order k generates a family of B-spline curves. We show that an envelope of this family is a B-spline curve defined by the same control polygon, and its order is k - m, where m is the multiplicity of the modified knot. Moreover, their arbitrary order derivatives differ only in a multiplier. (C) 2003 Elsevier Science B.V. All rights reserved.
b-spline curve envelope knot modification