Antonio Robles-Kelly Edwin R. Hancock Radiance Function Estimation for Object Classification. 67-75 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3287&spage=67 2004 conf/ciarp/2004 CIARP db/conf/ciarp/ciarp2004.html#Robles-KellyH04