Yueming Wang Gang Pan Zhaohui Wu Shi Han Sphere-Spin-Image: A Viewpoint-Invariant Surface Representation for 3D Face Recognition. 427-434 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3037&spage=427 2004 conf/iccS/2004-2 International Conference on Computational Science db/conf/iccS/iccS2004-2.html#WangPWH04