Depth silhouettes context: A new robust feature for human tracking and activity recognition based on embedded HMMs

Activity and action detection, tracking and recognition are very demanding research area in computer vision and human computer interaction. In this paper, a video-based novel approach for human activity recognition is presented using robust hybrid features and embedded Hidden Markov Models. In the proposed HAR framework, depth maps are analyzed by temporal motion identification method to segment human silhouettes from noisy background and compute depth silhouette area for each activity to track human movements in a scene. Several representative features, including invariant, depth sequential silhouettes and spatiotemporal body joints features were fused together to explore gradient orientation change, intensity differentiation, temporal variation and local motion of specific body parts. Then, these features are processed by the dynamics of their respective class and learned, trained and recognized with specific embedded HMM having active feature values. Our experiments on two depth datasets demonstrate that the proposed features are efficient and robust over the state of the arts features for human activity recognition especially when there are similar postures of different activities.