Modular radiance transfer

In ACM Transactions on Graphics (Proceedings of SIGGRAPH Asia), 2011
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Indirect light computed in reduced subspaces for a cave with 19 blocks and 4 lights. We derive low-dimensional transport operators, on simple proxy shapes, that are warped and combined at run-time, at > 475 FPS on high-end GPUs and > 45 FPS on mobile platforms, and can model indirect light at surfaces (with detailed normal variation) and within volumes of large-scale scene geometry.

Abstract

Many rendering algorithms willingly sacrifice accuracy, favoring plausible shading with high-performance. Modular Radiance Transfer (MRT) models coarse-scale, distant indirect lighting effects in scene geometry that scales from high-end GPUs to low-end mobile platforms. MRT eliminates scene-dependent precomputation by storing compact transport on simple shapes, akin to bounce cards used in film production. These shapes' modular transport can be instanced, warped and connected on-the-fly to yield approximate light transport in large scenes. We introduce a prior on incident lighting distributions and perform all computations in low-dimensional subspaces. An implicit lighting environment induced from the low-rank approximations is in turn used to model secondary effects, such as volumetric transport variation, higher-order irradiance, and transport through lightfields. MRT is a new approach to precomputed lighting that uses a novel low-dimensional subspace simulation of light transport to uniquely balance the need for high-performance and portable solutions, low memory usage, and fast authoring iteration.

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Cite

@article{loos11modular,
    author  = {Loos, Bradford J. and Antani, Lakulish and Mitchell, Kenny and Nowrouzezahrai, Derek and Jarosz,
               Wojciech and Sloan, Peter-Pike},
    title   = {Modular Radiance Transfer},
    journal = {ACM Transactions on Graphics (Proceedings of SIGGRAPH Asia)},
    volume  = {30},
    number  = {6},
    year    = {2011},
    month   = dec,
    doi     = {10/ddfbh9}
}

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