ABSTRACT
DEFORMATION SYSTEMS ARE RESPONSIBLE for how a model is impacted by the actions ofthe motion system. Deformations can be abstractly thought of as the muscles that stretch and bend skin in response to the motion of the body. In actuality, for animals, the muscles drive the skeleton, but for the purposes of animation, the inverse is true. Deformations can be as simple as a per-vertex connection to the joints that drive them and as complex as an anatomically based layered muscle system that drives successive layers of geometry. This chapter discusses the physiology of muscles in addition to the physical attributes of skin and the relationship between skin, muscle, and bone. An overview of deformation methods, including skinning, spring meshes, and shape interpolation taking into account the theory and code put these anatomical concepts into practice.
