Spatio-temporal elastic cuboid trajectories for efficient fight recognition using Hough forests

While action recognition has become an important line of research in computer vision, the recognition of particular events such as aggressive behaviors, or fights, has been relatively less studied. These tasks may be exceedingly useful in some video surveillance scenarios such as psychiatric centers, prisons or even in personal camera smartphones. Their potential usability has caused a surge of interest in developing fight or violence detectors. The key aspect in this case is efficiency, that is, these methods should be computationally very fast. In this paper, spatio-temporal elastic cuboid trajectories are proposed for fight recognition. This method is based on the use of blob movements to create trajectories that capture and model the different motions that are specific to a fight. The proposed method is robust to the specific shapes and positions of the individuals. Additionally, the standard Hough forests classifier is adapted in order to use it with this descriptor. This method is compared to other nine related methods on four datasets. The results show that the proposed method obtains the best accuracy for each dataset and is also computationally efficient.