This paper proposes a methodology to modify the shape of a NURBS curve by m
oving the nose points of each curve segment. To perform the modification, t
he algorithms of evaluating control point movements and weight changes are
first introduced, In weight changes, the derived equation for modifying a c
urve segment is viewed as an equilibrium force system, acting on the target
nose point and yielding the required nose point displacement, which provid
es the foundation for the algorithm to attain the required curve modificati
on. To raise the precision and efficiency of curve modification, a method o
f constraining the joining points and the nose points is proposed. In addit
ion, a method is presented to reach an optimal solution to curve modificati
on, and is verified in the implementation. (C) 1998 Elsevier Science Ltd. A
ll rights reserved.