TURAGA P ET AL: 'Machine Recognition of Human Activities: A Survey', IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, IEEE SERVICE CENTER, PISCATAWAY, NJ, US, vol. 18, no. 11, 1 November 2008 (2008-11-01), pages 1473 - 1488, XP011235232, ISSN: 1051-8215, DOI: 10.1109/TCSVT.2008.2005594