Robust quasistatic finite elements and flesh simulation

  • Authors:
  • Joseph Teran;Eftychios Sifakis;Geoffrey Irving;Ronald Fedkiw

  • Affiliations:
  • Stanford University;Stanford University, Intel Corporation;Stanford University, Pixar Animation Studios;Stanford University, Industrial Light+Magic

  • Venue:
  • Proceedings of the 2005 ACM SIGGRAPH/Eurographics symposium on Computer animation
  • Year:
  • 2005

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Abstract

Quasistatic and implicit time integration schemes are typically employed to alleviate the stringent time step restrictions imposed by their explicit counterparts. However, both quasistatic and implicit methods are subject to hidden time step restrictions associated with both the prevention of element inversion and the effects of discontinuous contact forces. Furthermore, although fast iterative solvers typically require a symmetric positive definite global stiffness matrix, a number of factors can lead to indefiniteness such as large jumps in boundary conditions, heavy compression, etc. We present a novel quasistatic algorithm that alleviates geometric and material indefiniteness allowing one to use fast conjugate gradient solvers during Newton-Raphson iteration. Additionally, we robustly compute smooth elastic forces in the presence of highly deformed, inverted elements alleviating artificial time step restrictions typically required to prevent such states. Finally, we propose a novel strategy for treating both collision and self-collision in this context.