Ivo Ihrke Gernot Ziegler Art Tevs Christian Theobalt Marcus A. Magnor Hans-Peter Seidel Eikonal rendering: efficient light transport in refractive objects. 59 2007 26 ACM Trans. Graph. 3 http://doi.acm.org/10.1145/1276377.1276451 db/journals/tog/tog26.html#IhrkeZTTMS07