33 - Physical Modelling for Animating Cloth Motion

Abstract

This chapter describes physical modeling for animating cloth motion. Computer animation of cloth motion has implications for many graphics applications. In this chapter an approximate physics-based model is proposed for obtaining realistic animation of cloth motion for computer graphics applications. The model is constructed based on concepts from structural dynamics and low-speed wing aerodynamic theories with some modifications. Concepts from low-speed unsteady aerodynamic theory of wings coupled with proper boundary conditions to account for the porosity of cloth and the effects of the presence of boundaries such as walls near a moving piece of cloth are used to estimate the unsteady force distributions on the cloth surface which is assumed to be in motion in free air. The motivation for using aerodynamic theory is to model a distributed force model as opposed to using predefined concentrated force models, thereby incorporating some form of automatic control for the synthesis of the complex shapes the cloth can take and for obtaining realistic motion. These force distributions are then used in a cloth deformation model to estimate the displacements of various points of the cloth at different instants of time.