Deformable Characters


Many real objects (especially living ones such as humans) are flexible, not rigid.  Such deformable objects exhibit complex motion that is tedious (or impossible) to animate by hand.  This project explores the physical simulation of deformable objects for computer animation.  In particular, we are interested in the animation of characters such as humans and animals.  Our goal is to create efficient and user-friendly methods of simulating deformable characters, and to provide the animator with tools for controlling the pose and shape of the character, within an elastic simulation paradigm.



Physically Based Rigging for Deformable Characters
Steve Capell, Matthew Burkhart, Brian Curless Tom Duchamp, Zoran Popović
Proceedings of the 2005 ACM SIGGRAPH / Eurographics Symposium on Computer Animation
(won the 2005 Best Paper Award Honorable Mention)
paper (PDF, 4MB)
video: large (DivX, 640x480, 64MB), small (DivX, 320x240, 30MB)
An extended version of this paper was published in Graphical Models, vol. 69, p. 71-87, 2007. If you would like an electronic copy for non-commercial research and educational use only, please email Steve Capell (see the Grail people page).

Interactive Character Animation Using Dynamic Elastic Simulation
Steve Capell
Ph.D. Dissertation, University of Washington, Department of Computer Science and Engineering, 2004
dissertation (PDF, 24MB)

Interactive Skeleton-Driven Dynamic Deformations
Steve Capell, Seth Green, Brian Curless Tom Duchamp, Zoran Popović
Proceedings of ACM SIGGRAPH 2002
paper (PDF, 1.7MB)
video: Quicktime (68MB), DivX (33MB)
talk slides (Slithy, 40MB)

A Multiresolution Framework for Dynamic Deformations
Steve Capell, Seth Green, Brian Curless Tom Duchamp, Zoran Popović
Proceedings of the 2002 ACM SIGGRAPH Symposium on Computer Animation
paper (PDF, 0.7MB)
talk slides (PowerPoint, 50MB)

Additional Video Clips

Click on the images below to view Quicktime movies (about 1-5 megabytes each).

A chain-like object described by volumetric MacCracken-Joy subdivision with sharp surface creases.  Cyan spheres represent position constraints.
A cucumber-like object with spatially varying material properties.  The left side is firm but the right side is very flexible.  The user shakes the object by grabbing it in the middle.
The chain-like object being thrown about in a virtual room.
A duck, also modeled directly using volumetric MacCracken-Joy subdivision.
A soda can.
The soda can can be made very soft at runtime.
A goopy blob can be made to leap in the air by abruptly changing the global modulus of rigidity.
A dragon is adaptively simulated.  The simulation begins with only coarse basis functions (represented as red spheres).  The user applies a position constraint to open the mouth of the dragon.  In areas of high deformation, finer basis functions are introduced (shown in green and blue).
A cow being animated via an underlying skeleton.  Only the skeletal motion is specified by the animator.  The secondary motion of the flesh is simulated in real time.
Another view of the cow animation.  Notice how the horns are rigid but the ears are more flexible.  The stomach also sways back and forth realistically.
Position constraints can be imposed along with skeletal constraints.

This research is supported by: