Markerless body part tracking for action recognition

This paper presents a method for recognizing human actions by tracking body parts without using artificial markers. A sophisticated appearance-based tracking able to cope with occlusions is exploited to extract a probability map for each moving object. A segmentation technique based on mixture of Gaussians (MoG) is then employed to extract and track significant points on this map, corresponding to significant regions on the human silhouette. The evolution of the mixture in time is analyzed by transforming it in a sequence of symbols (corresponding to a MoG). The similarity between actions is computed by applying global alignment and dynamic programming techniques to the corresponding sequences and using a variational approximation of the Kullback-Leibler divergence to measure the dissimilirity between two MoGs. Experiments on publicly available datasets and comparison with existing methods are provided.