Constructing Physics - Based Facial Models of Individuals

This paper develops a highly automated approach to constructing realistic, working models of human heads for use in animation. Th ese physics-based models are anatomically accurate and may be made to conform closely to specific individuals . We begin by scanning a person with a laser sensor which circles around th e head, acquiring detailed range and reflec tance information . Next, an automatic conformation algorithm adapts a triangulated fa ce m esh of predetermined topological structure to thes e data. Th generic mesh, which is reusable with different individuals , reduces the range data to an effi cient, polygonal approximation of the fa cial geometry and supports a high-resolution texture mapping of th e skin refl ec tivity. Th e conformed polygonal mesh forms th e epidermal layer of a new, physics-based model of facial tissu e. A n automatic algorithm constructs the multilayer synthetic skin and estimates an underlying rigid "skull" substructure with a j ointed jaw. Finally, th e algorithm inserts synthetic muscles into the deepest layer of th e fa cial tissue. Th ese co ntractile actuators, which emulate the primary muscles of fa cial expression, generate f orces that deform th e synthetic tissue into m eaningful expressions. To increase realism, we include constraints to emulate tissue incompressibility and to enable th e tissue to slide over the skull substructure without penetrating into it. The resulting animate models appear significantly more realistic than our previous physics-based fa cial m odels.