A solid volumetric deformable muscle model for computer animation using weighted residual method

One of the most important yet expensive tasks in realistic character animat ion is to represent the body deformation, i.e. the deformation of the muscl es. Because of the complexity of the geometry and deformable behaviours of such muscle tissues. three-dimensional (3D) finite element analysis (FEA) i s usually employed. FEA however, requires enormous computing power, and oft en is impractical for computer animation where computational cost needs to be balanced with modelling accuracy. In this sense, it differs From enginee ring analysis where accuracy is often paramount for many applications, such as in aviation industry. Proposed in this paper is a 3D solid volumetric d eformable muscle model which is almost as accurate as the FEA, but requires only a fraction of the computing cost. In this model, the muscle tissues a re assumed to be elastic bodies with isotropic behaviour. The governing equ ations are derived and a weighted residual method is introduced to solve th ese equations. Suitable trial functions are proposed which satisfy the defo rmation compatibility and equilibrium equations. Using the least squares te chnique, the residual values on the boundaries are formulated and minimised to determine the unknown constants in the trial functions. In order to val idate our model, the numerical results produced by our model are compared w ith the finite element computation and it is found that the two results clo sely agree with each other. (C) 2000 Elsevier Science S.A. All rights reser ved.