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Figure 1: Left: Real-time global illumination on a static 2.3M triangle scene. Both the light and the viewpoint can be moved freely at 7-21 frames per second after a little less than half an hour of precomputation on a single PC. Right: The indirect illumination expressed in our meshless hierarchical basis (emphasized for visualization). Green dots represent non-zero coefficients. AbstractWe introduce a meshless hierarchical representation for solving light transport problems. Precomputed radiance transfer (PRT) and finite elements require a discrete representation of illumination over the scene. Non-hierarchical approaches such as per-vertex values are simple to implement, but lead to long precomputation. Hierarchical bases like wavelets lead to dramatic acceleration, but in their basic form they work well only on flat or smooth surfaces. We introduce a hierarchical function basis induced by scattered data approximation. It is decoupled from the geometric representation, allowing the hierarchical representation of illumination on complex objects. We present simple data structures and algorithms for constructing and evaluating the basis functions. Due to its hierarchical nature, our representation adapts to the complexity of the illumination, and can be queried at different scales. We demonstrate the power of the new basis in a novel precomputed direct-to-indirect light transport algorithm that greatly increases the complexity of scenes that can be handled by PRT approaches.

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Figure 1: A cityscape from the DreamWorks Animation movie "Kung Fu Panda 2". The out-of-core method described in our paper shaded the global illumination for the whole frame in 6 minutes 23 seconds. It used 128 million points, and it took an additional 4 minutes 18 seconds to build the out-of-core octree, resulting in 27 million octree nodes. The total amount of outof-core data was 6.8 GB while the in-core point and node caches' memory usage did not exceed 2 GB. The cache hit rate was 99%. In Section 7, we demonstrate usage of up to 1.7 billion points (88 GB of data) within a 2 GB memory cap. AbstractWe describe a new technique for coherent out-of-core point-based global illumination and ambient occlusion. Point-based global illumination (PBGI) is used in production to render tremendously complex scenes, so in-core storage of point and octree data structures quickly becomes a problem. However, a simple out-of-core extension of a classical top-down octree building algorithm would be extremely inefficient due to large amount of I/O required. Our method extends previous PBGI algorithms with an out-of-core technique that uses minimal I/O and stores data on disk compactly and in coherent chunks for later access during shading. Using properties of a space-filling Z-curve, we are able to preprocess the data in two passes: an external 1D-sort and an octree construction pass.

Figure 1: Left: Real-time global illumination on a static 2.3M triangle scene. Both the light and the viewpoint can be moved freely at 7-21 frames per second after a little less than half an hour of precomputation on a single PC. Right: The indirect illumination expressed in our meshless hierarchical basis (emphasized for visualization). Green dots represent non-zero coefficients. AbstractWe introduce a meshless hierarchical representation for solving light transport problems. Precomputed radiance transfer (PRT) and finite elements require a discrete representation of illumination over the scene. Non-hierarchical approaches such as per-vertex values are simple to implement, but lead to long precomputation. Hierarchical bases like wavelets lead to dramatic acceleration, but in their basic form they work well only on flat or smooth surfaces. We introduce a hierarchical function basis induced by scattered data approximation. It is decoupled from the geometric representation, allowing the hierarchical representation of illumination on complex objects. We present simple data structures and algorithms for constructing and evaluating the basis functions. Due to its hierarchical nature, our representation adapts to the complexity of the illumination, and can be queried at different scales. We demonstrate the power of the new basis in a novel precomputed direct-to-indirect light transport algorithm that greatly increases the complexity of scenes that can be handled by PRT approaches.