Stina Svensson Carlo Arcelli Gabriella Sanniti di Baja Characterising 3D Objects by Shape and Topology. 124-133 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2886&spage=124 2003 conf/dgci/2003 DGCI db/conf/dgci/dgci2003.html#SvenssonAB03