Modular Radiance Transfer
Bradford J. Loos (Disney Interactive Studios Intern)
Lakulish Antani (Disney Interactive Studios Intern)
Kenny Mitchell (Disney Research Los Angeles)
Derek Nowrouzezahrai (Disney Research Zurich)
Wojciech Jarosz (Disney Research Zurich)
Peter-Pike Sloan (Disney Interactive Studios)
Modular Radiance Transfer is an approach for interactively computing approximate direct-to-indirect transfer by warping and combining transport from a library of simple shapes. Incorporating precomputed light transport into authoring pipelines for large scenes incurs long preprocessing times, generates large datasets, hinders artistic iteration workflows, and often results in only modest run-time performance. We observe that using a prior on the distribution of incident lighting enables accurate low-rank approximations to the light transport operator for simple canonical shapes, which can be precomputed off-line. An implicit lighting environment induced from the low-rank approximation is then used to model the flow of light volumetrically in the scene and through interface lightfields between shapes. These interfaces enable coupling between shapes and act as aggregation points for distant propagation, increasing the runtime performance and minimizing the required memory. We replace the scene dependent precomputation with a light-weight, artist driven mapping between the complex scene and the dictionary of shapes. High frame rates are produced on target platforms ranging from cell-phones to high end GPUs.