Character Animation using Hierarchical B-Splines

The challenge of building and animating computer generated human and animal figures is complicated by the need to smoothly and realistically control the deformation of the surface around the articulations of the underlying skeleton. This paper reviews approaches to surface modelling for character animation and describes a geometric (as apposed to physically-based) approach to character modelling using an extension to the hierarchical B-spline. This techinique provides differential attachment of the surface to the skeleton and allows multi-resolution control of surface deformation during animation. The attachment mechanism is simple, easy to use, inexpensive, extensible and can drastically reduce the effort required to animate a surface. The techniques introduced are illustrated using examples of human and animal forms.