Computer animation, for many people, is synonymous with big-screen events such as Star Wars, Toy Story, and Titanic . But not all, or arguably even most, computer animation is done in Hollywood. It is not unusual for Saturday morning cartoons to be entirely computer generated. Computer games take advantage of state-of-the-art computer graphics techniques and have become a major motivating force driving research in computer animation. Real-time performance-driven computer animation has appeared at SIGGRAPH 1 and on Sesame Street. Desktop computer animation is now possible at a reasonable cost. Computer animation on the web is routine. Digital simulators for training pilots, SWAT teams, and nuclear reactor operators are commonplace. The distinguishing characteristics of these various venues are the cost, the image quality desired, and the amount and type of interaction allowed. This book does not address the issues concerned with a particular venue, but it does present algorithms and techniques used to do computer animation in all of them.