Abstract:A 3D facial expressional motion tracking algorithm based on online model adaptation and updating is proposed. The algorithm constructs the online model using an adaptive statistic observation model. With the combination of adaptive state transition model and improved particle filter, statistic search and determinately search are proposed simultaneously. Multi-measurements are infused to decrease lighting influence and person dependence. With this algorithm, the global rigid motion parameters and local non rigid expressional parameters are obtained. Experiment result confirms the effective ness of the proposed algorithm.