[HPB06]
Cornell University Program of Computer Graphics 

Directtoindirect transfer for cinematic relighting.Milos Hasan, Fabio Pellacini, and Kavita Bala.ACM Trans. Graph., 25(3):10891097, 2006. This paper presents an interactive GPUbased system for cinematic relighting with multiplebounce indirect illumination from a fixed viewpoint. We use a deep framebuffer containing a set of view samples, whose indirect illumination is recomputed from the direct illumination on a large set of gather samples, distributed around the scene. This directtoindirect transfer is a linear transform which is particularly large, given the size of the view and gather sets. This makes it hard to precompute, store and multiply with. We address this problem by representing the transform as a set of sparse matrices encoded in wavelet space. A hierarchical construction is used to impose a wavelet basis on the unstructured gather cloud, and an imagebased approach is used to map the sparse matrix computations to the GPU. We precompute the transfer matrices using a hierarchical algorithm and a variation of photon mapping in less than three hours on one processor. We achieve highquality indirect illumination at 1020 frames per second for complex scenes with over 2 million polygons, with diffuse and glossy materials, and arbitrary direct lighting models (expressed using shaders). We compute perpixel indirect illumination without the need of irradiance caching or other subsampling techniques.
This paper is available as a PDF file HPB06.pdf (305K).
 
