Single Scattering in Refractive Media with
Triangle Mesh Boundaries

Bruce Walter Cornell University
Shuang Zhao Cornell University
Nicolas Holzschuch INRIA - LJK
Kavita Bala Cornell University


ACM SIGGRAPH 2009 (August 2009)


      Light scattering in refractive media is an important optical phenomenon for computer graphics. While recent research has focused on multiple scattering, there has been less work on accurate solutions for single or low-order scattering. Refraction through a complex boundary allows a single external source to be visible in multiple directions internally with different strengths; these are hard to find with existing techniques. This paper presents techniques to quickly find paths that connect points inside and outside a medium while obeying the laws of refraction. We introduce: a half-vector based formulation to support the most common geometric representation, triangles with interpolated normals; hierarchical pruning to scale to triangular meshes; and, both a solver with strong accuracy guarantees, and a faster method that is empirically accurate. A GPU version achieves interactive frame rates in several examples.


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This work was supported by NSF CAREER 0644175, NSF CPA 0811680, NSF CNS 0615240, NSF CNS 0403340, and grants from Intel Corporation, NVidia Corporation, and Microsoft Corporation. This work was started while N. Holzschuch was on a sabbatical at Cornell, funded by INRIA, and he'd like to acknowledge the INRIA CIPRUS associate team. LJK is UMR 5224, a joint research laboratory of CNRS, INRIA, INPG, U. Grenoble I and U. Grenoble II.