MIRALab Copyright © Information 1998 Developing Simulation Techniques for an Interactive Clothing System Pascal Volino and Nadia Magnenat Thalmann MIRALab, University of Geneva Abstract In this contribution towards creating interactive environments for garment design and simulation, we present a powerful mechanically based cloth simulation system. It is based on an optimized way to compute elastic forces between vertices of an irregular triangle mesh, which combines the precision of elasticity modelisation with the speed of a simple spring-mass particle system. Efficient numerical integration error management keeps computation speed efficient by allowing high computation timesteps and also maintains very good stability, suitable for interactive applications. Constraints, such as collisions or "elastics", are integrated in a unified way that preserves robustness and computation speed. We illustrate the potentialities of our new system through examples showing its efficiency and interactivity. Keywords : cloth animation, mechanical simulation, particle systems, collision response, constraints, stability, interaction, garment design tools 1. Introduction In a step towards unifying cloth simulation to the wonderful universe of Virtual Reality and dreaming about a world where virtual humans could manipulate cloth in real time and in a way that seems so natural for us, real humans, we present a contribution for a fast and robust cloth model suited for interactive virtual cloth design and simulation system. Literature now brings us several techniques for cloth simulation. Many of them present physically based models for simulating in a realistic way fabric pieces based on elastic deformation and collision response. The first of them used simple mechanically-based models, such as relaxation schemes, for simulating objects such as flags or curtains ([WEI 86], [HAU 88]). More general elastic models were developed for simulating a wide range of deformable objects, including cloth ([TER 87], [TER 88]). Recently, several particle system based models attempted to simulate simple cloth object realistically using experimental fabric deformation data ([BRE 94], [EBE 96]). These models claim to be fast and flexible, as opposed to finite element models ([COL 91], [KAN 95], [EIS 96]), which are very accurate, but slow and complex to use in situations where behavior models are complicated and where collisions create non-linearities and complex boundary conditions, thus not suited for interactive applications. Dressing a virtual body is a complex application for these models. It involves the ability to design complex garment shapes, as well as a complex simulation system able to detect and to