Muscle modeling for facial animation in videophone coding

An innovative knowledge-based scheme is presented for videophone sequence coding, with a reasonable subjective reconstruction quality. The videophone images are segmented and approximated by means of a suitably adapted 3D wire-frame model capable of faithfully reproducing the signal temporal evolution through a limited number of updating parameters extracted from the real sequence. The muscle modeling represents the basic issue for the analysis of facial expressions at the encoder and for their synthesis at the decoder. Facial muscles are modeled either as linear fibers or as circular fibers and are characterized by descriptive parameters such as thickness, length, position and direction. The animation is performed by simulating the muscle contraction and relaxation over the domain of influence defined by the muscle parameters. The interactive procedure for the construction and adaptation of the 3D model and the analysis/synthesis algorithms, implemented on a multiprocessor AT&T Pixel Machine, are described, together with some examples of the achieved experimental results