Daniel Vlasic Hanspeter Pfister Sergey Molinov Radek Grzeszczuk Wojciech Matusik Opacity light fields: interactive rendering of surface light fields with view-dependent opacity. 75-82 2003 SI3D http://doi.acm.org/10.1145/641480.641496 db/conf/si3d/si3d2003.html#VlasicPMGM03