Dynamics for Animation of Characters with Deformable Surfaces

Abstract

The animation of human and human-like characters is one of the major problems in computer animation (Badler 1982). The key aspect of this problem is achieving realistic motion with a minimal amount of effort on the part of the animator. The control of a dynamic animation by means of joint torque and force functions has been described by Wilhelms and Barsky (1985). Their solution to the dynamics problem uses a Gibbs-Appell formulation, according to which the time to set up the equations grows at least as the cube of the number of links. After that, the solution time is at least quadratic, due to the fact that a square matrix having several rows for each link is employed. Formulating the problem using such a matrix is not essential for animating tree-like figures, however. The fact that the only dynamic interactions which occur between links are those between parents and their children means that the solution can be carried out more efficiently.