Combining Global and Local Virtual Lights for Detailed Glossy Illumination
Tomas Davidovic, Jaroslav Krivanek, Milos Hasan, Phillip Slusallek, Kavita Bala
Proceedings of SIGGRAPH Asia 2010
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Abstract:
Accurately rendering glossy materials in design applications, where previewing
and interactivity are important, remains a major chal- lenge. While many fast
global illumination solutions have been pro- posed, all of them work under
limiting assumptions on the materials and lighting in the scene. In the
presence of many glossy (direc- tionally scattering) materials, fast solutions
either fail or degenerate to inefficient, brute-force simulations of the
underlying light trans- port. In particular, many-light algorithms are able to
provide fast approximations by clamping elements of the light transport matrix,
but they eliminate the part of the transport that contributes to accu- rate
glossy appearance. In this paper we introduce a solution that separately solves
for the global (low-rank, dense) and local (high- rank, sparse) illumination
components. For the low-rank compo- nent we introduce visibility clustering and
approximation, while for the high-rank component we introduce a local light
technique to correct for the missing illumination. Compared to competing
techniques we achieve superior gloss rendering in minutes, making our technique
suitable for applications such as industrial design and architecture, where
material appearance is critical.