Hanning Zhou Thomas S. Huang Recovering Articulated Motion with a Hierarchical Factorization Method. 140-151 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2915&spage=140 2003 conf/gw/2003 Gesture Workshop db/conf/gw/gw2003.html#ZhouH03