A movable jaw model for the human face

Abstract

Although there is a great deal of work on facial animation, there is not much research on the effect of jaw motion on the movement of the face. The complex nature of the jaw bones makes it difficult to implement all the motions the jaw can do. The human jaw has two widely separated identical joints behaving like a single joint. Widely separated joints of the mandible (lower jaw bone) allow it to translate in any direction and/or rotate about any axis in three-dimensional space although its movements are somewhat restricted by physical constraints and patterns of muscle activity. A simplified jaw model which covers the major movements of the jaw is proposed in this paper. The lower jaw in the model can rotate around the axis connecting the two ends of the jaw and make small translational motions in any direction in 3-D space. The face is modeled as a two layer model which is attached to the jaw. The inner layer of the face moves kinematically as dictated by the jaw. The outer layer moves with the effect of the springs connecting it to the inner layer. The motion of the outer layer is calculated using spring-mass equations. Eating and chewing actions are simulated as applications of the model.