Our ICIAP paper “Space-time Zernike Moments and Pyramid Kernel Descriptors for Action Classification” is available online.
Action recognition in videos is a relevant and challenging task of automatic semantic video analysis. Most successful approaches exploit local space-time descriptors. These descriptors are usually carefully engineered in order to obtain feature invariance to photometric and geometric variations. The main drawback of space-time descriptors is high dimensionality and efficiency. In this paper we propose a novel descriptor based on 3D Zernike moments computed for space-time patches.Moments are by construction not redundant and therefore optimal for compactness. Given the hierarchical structure of our descriptor we pro-pose a novel similarity procedure that exploits this structure comparing features as pyramids. The approach is tested on a public dataset and compared with state-of-the art descriptors.