This book contains several invited papers and a selection of research papers submitted to Computer Animation '92, the fourth international workshop on Computer Animation, which was held in Geneva on May 20-22. This workshop, now an annual event, has been organized by the Computer Graphics Society, the University of Geneva, and the Swiss Federal Institute of Technology in Lausanne. During the international workshop on Computer Animation '92, the fifth Computer-generated Film Festival of Geneva, was held. The book presents original research results and applications experience in various areas of computer animation. This year most papers are related to physics-based animation, human animation, and geometric modelling for animation. NADIA MAGNENAT THALMANN DANIEL THALMANN Table of Contents Part I: Physics-based Animation The Control of Hovering Flight for Computer Animation David Haumann, Jessica K. Hodgins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Inverse Problems in Computer Graphics Michael Kass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 NPSNET: Physically-based Modeling Enhancements to An Object File Format Michael J. Zyda, James G. Monahan, David R. Pratt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 A New Method for Approximative Interactive Dynamics Ulrich Leiner, Bernhard Preim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Part ll: Human animation Extraction of 3D Shapes from the Moving Human Face Using Lighting Swjtch Photometry Hitoshi Saji, Hirohisa Hioki, Yoshihisa Shinagawa, Kensyu Yoshida, Tosiyasu L. Kunii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 An Interactive Tool for the Design of Human Free-Walking Trajectories Laurent Bezault, Ronan Boulic, Nadia Magnenat Thalmann, Daniel Thalmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Achilles - A System for Visualizing Non Standard Human Gait Homero L. Piccolo, Kentaro Takahashi, Marcus G. de Amorim, Andre C. de Sa Carneiro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .