Animating deformable models: different approaches

Physically-based modeling remedies the problem of producing realistic animation by including forces, masses, strain energies, and other physical quantities. The behavior of physically-based models is governed by the laws of rigid and nonrigid dynamics expressed through a set of equations of motion. This paper discusses various formulations for animating deformable models. The formulations based on elasticity theory express the interactions between discrete deformable model points using the stiffness matrices. These matrices store the elastic properties of the models and they should be evolved in time according to changing elastic properties of the models. An alternative to these formulations seems to be external force formulations of different types. In these types of formulations, elastic properties of the materials are represented as external spring or other tensile forces as opposed to forming complicated stiffness matrices.