A Piecewise Bézier Volume Deformation Model and Its Applications in Facial Motion Capture

Capturing real facial motions from videos enables automatic creation of dynamic models for facial animation. In this paper, we propose an explanation-based facial motion tracking algorithm based on a piecewise Bézier volume deformation model (PBVD). The PBVD is a suitable model both for synthesis and analysis of facial images. With this model, basic facial movements, or action units, are first interactively defined. Then, by linearly combining these action units, various facial movements are synthesized. The magnitudes of these action units can be estimated from real videos using a model-based tracking algorithm. The predefined PBVD action units may also be adaptively modified to customize the dynamic model for a particular face. In this paper, we first briefly introduce the PBVD model and its application in computer facial animation. Then a coarse-to-fine PBVD-based motion tracking algorithm is presented. We also describe an explanation-based tracking algorithm that takes a collection of predefined action units as the initial dynamic model and adaptively improves this model during the tracking process. Experimental results on PBVD-based animation, model-based tracking, and explanation-based tracking are demonstrated.