Hybrid anatomically based modelling of animals

The authors describe a new hybrid approach to modeling and animating animals. A pre-defined skin is modeled as a triangle mesh, such as may be purchased from a digital model vendor, or generated with a typical modeling program. This skin is then attached to the underlying bone, muscle, and tissue model. The rest shape of the skin is exactly as given in the surface model of the animal. Internal components-bones, muscles, and general tissue-are directly modeled with triangle meshes or ellipsoids. Changes in joint angle result in changes to the position of bones and generalized tissue, and in changes to the shapes of muscles. The attached skin vertices move with their underlying components, resulting in natural-looking deformations to the animal modeled. This alternative approach to modeling skin allows for greater realism or detail without requiring more accurate internals, and it allows pre-existing animal models to be realistically deformed using an anatomically based method.