A Kinematic Model for Collision Response

by Jason Harrison

A Thesis Submitted in Partial Fulfullment of the Requirements for the Degree of Master of Science in the Faculty of Graduate Studies, Department of Computer Science, University of British Columbia. April 1994.


Over the course of several years, an informal poll by Dave Forsey of commercial animators revealed that the single most useful tool to add to a computer animation system would be a way to control the simple act of pressing one object into another. This ability would drastically increase the range and style of animations that could be created within a production environment.

This thesis presents a simple, fast, geometric approach to controlling the nature, extent and timing of the surface deformations arising from the interpenetration of kinematically controlled animated objects.

Rather than using dynamic simulations, which are difficult to configure, code, and control, the algorithm presented here is based upon the idea that collision response is a matter of moving specific points on the surface towards specific goal points at a certain rate. This is an operation similar to manipulating chains of rigid bodies using inverse kinematics. This formulation is easily extendable to free-form surface modeling where generally only one point, or possibly more, is manipulated interactively at a time.

We use a multi-resolution approach to deformations to provide control over the response of the surface using a small number of parameters. Each of the parameters determine how a level in the multi-resolution representation of the surface reacts to the interpenetration. The deformations are calculated in time and space proportional to the number of points used to define the surface.

Click here to obtain a Gnuzipped PostScript version of this thesis (500 K bytes).

Here is a paper written for the Eurographics'94 Workshop on Animation and Simulation (13 K bytes).

This is http://www.cs.ubc.ca/spider/harrison/Thesis/thesis.html.
Maintained by Jason Harrison (harrison@cs.ubc.ca). Last modified: Wed Aug 12 16:34:35 1998.