Physics-based Character Skinning using Multi-Domain Subspace Deformations

ACM SIGGRAPH / Eurographics Symposium on Computer Animation (SCA) 2011

Theodore Kim
University of California, Santa Barbara
and University of Saskatchewan
Doug L. James
Cornell University

We propose a domain-decomposition method to simulate articulated deformable characters entirely within a subspace framework. The method supports quasistatic and dynamic deformations, nonlinear kinematics and materials, and can achieve interactive time-stepping rates. To avoid artificial rigidity, or "locking," associated with coupling low-rank domain models together with hard constraints, we employ penalty-based coupling forces. The multi-domain subspace integrator can simulate deformations efficiently, and exploits efficient subspace-only evaluation of constraint forces between rotated domains using the so-called Fast Sandwich Transform (FST). Examples are presented for articulated characters with quasistatic and dynamic deformations, and interactive performance with hundreds of fully coupled modes. Using our method, we have observed speedups of between three and four orders of magnitude over full-rank, unreduced simulations.

Paper download [PDF, 10.2 MB]
Video download [MOV, 74.6 MB]
Individual video clips, including several not in the main video, are also available. Many of the clips are longer than the segments shown in the main video, and display additional deformations and dynamics.

Code Available:

Cubica is a toolkit for efficient finite element simulations of deformable bodies containing both geometric and material non-linearities. Its main feature is its use of subspace methods, also known as dimensional model reduction or reduced-order methods, which can accelerate simulations by several orders of magnitude.

This work was supported in part by the National Science Foundation (CAREER-0430528, EMTCompBio-0621999), the National Institutes of Health (NIBIB/NIH R01EB006615), NSERC (Many-core Physically Based Simulations), the Alfred P. Sloan Foundation, and donations from Intel, Pixar, and Autodesk.