Authors Janez Perš Vildana Sulic Matej Kristan, PhD M. Perše K. Polanec Stanislav Kovacic Tagsactivity Histograms of optical flow for efficient representation of body motion Janez Perš, Vildana Sulic, Matej Kristan, M. Perše, K. Polanec and Stanislav Kovacic Pattern Recognition Letters, 2010,