Muscle Simulation with Extended Position Based Dynamics

Abstract

Recent research on muscle simulation for Visual Effects relies on numerical methods such as the Finite Element Method or Finite Volume Method. These approaches produce realistic results, but require high computational time and are complex to set up. On the other hand Position Based Dynamics offers a fast and controllable solution to simulate surfaces and volumes, but there is no literature on how to implement constraints that could be used to realistically simulate muscles for digital creatures with this method. In this paper we extend the current state-of-the-art in Position Based Dynamics to efficiently compute realistic skeletal-muscle simulation. In particular we embed muscle fibers in the solver by adding an anisotropic component to the distance constraints between mesh points and apply overpressure to realistically model muscle volume changes under contraction. We also present a technique that consistently provides an internal structure for our muscle volumes. We use this structure to preserve the shape and extract relevant information for the activation of the muscle fibers. Finally, we propose a modification of the Extended Position Based Dynamics algorithm and describe other details for proper simulation of character’'s muscle dynamics.