Computer Graphics

University of California - Berkeley

Interactive Deformation Using Modal Analysis with Constraints


Modal analysis provides a powerful tool for efficiently simulating the behavior of deformable objects. This paper shows how manipulation, collision, and other constraints may be implemented easily within a modal framework. Results are presented for several example simulations. These results demonstrate that for many applications the errors introduced by linearization are acceptable, and that the resulting simulations are fast and stable even for complex objects and stiff materials.


Kris K. Hauser, Chen Shen, and James F. O'Brien. "Interactive Deformation Using Modal Analysis with Constraints". In Graphics Interface, pages 247–256. CIPS, Canadian Human-Computer Commnication Society, June 2003.

Supplemental Material


Playstation2 interaction video. The user interacts with a "dough-like person", poking, prodding, pulling, and shaking it. Captured in real time on the Playstation2.


A rubber dodo medley!


Three rubber dodos fall from the sky.


A rubber dodo is blasted in the stomach by a hurtling bouncy ball.


A brain is smashed to left field by a (invisible) batter.


Two balls bounce and collide.


Four balls bounce on a sheet.


A ball rolls across a sheet.


A stretchy pendulum made of elastic spheres knocks a gelatinous cube.


A rubbery Stanford bunny hops along.

Source Code

The source code for this project (modified for public release) is available here. Note that there are a few bugs as well as a mysterious speed loss from our internally used program. The reasons for this are not yet found, but we will be sure to try our best to fix these problems as soon as possible. Version 0.5, May 18 2003.