Demetri Terzopoulos

"Physically-based techniques facilitate the creation of models capable of automatically synthesizing complex shapes and realistic motions that were, until recently, attainable only by skilled animators, if at all."

"Physically-based modeling adds new levels of representation to graphics objects. In addition to geometry — forces, torques, velocities, accelerations, kinetic and potential energies, heat, and other physical quantities are used to control the creation and evolution of models. Simulated physical laws govern model behavior, and animators can guide their models using physically-based control systems. Physically-based models are responsive to one another and to the simulated physical worlds that they inhabit."

"I would like to talk about deformable models, which are physically-based models of nonrigid objects. I have worked on deformable models for graphics applications primarily with Kurt Fleischer and also with John Platt and Andy Witkin. Deformable models are based on the continuum mechanics of flexible materials. Using deformable models, we can model the shapes of flexible objects like cloth, plasticine, and skin, as well as their motions through space under the action of forces and subject to constraints."

"Here is a simulated physical world — a very simple world consisting of a room with walls and a floor. A spherical obstacle rests in the middle of the floor. You’re seeing the collision of an elastically deformable solid with the sphere. Of course, we’re also simulating gravity."