Single Scattering in Refractive Media with Triangle Mesh Boundaries
Bruce Walter, Shuang Zhao, Nicolas Holzschuch, Kavita Bala
Proceedings of SIGGRAPH 2009 (SIGGRAPH 2009)
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Abstract:
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.