Daniel Ponsa F. Xavier Roca Multiple Model Approach to Deformable Shape Tracking. 782-792 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2652&spage=782 2003 conf/ibpria/2003 IbPRIA db/conf/ibpria/ibpria2003.html#PonsaR03