High-Performance Graphics 2011

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https://diglib.eg.org/handle/10.2312/324

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Browsing High-Performance Graphics 2011 by Subject "Color"

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    The Alchemy Screen-Space Ambient Obscurance Algorithm
    (ACM, 2011) McGuire, Morgan; Osman, Brian; Bukowski, Michael; Hennessy, Padraic; Carsten Dachsbacher and William Mark and Jacopo Pantaleoni
    Ambient obscurance (AO) produces perceptually important illumination effects such as darkened corners, cracks, and wrinkles; proximity darkening; and contact shadows. We present the AO algorithm from the Alchemy engine used at Vicarious Visions in commercialgames. It is based on a new derivation of screen-space obscurance for robustness, and the insight that a falloff function can cancel terms in a visibility integral to favor efficient operations. Alchemy creates contact shadows that conform to surfaces, capturesobscurance from geometry of varying scale, and provides four intuitive appearance parameters: world-space radius and bias, and aesthetic intensity and contrast. The algorithm estimates obscurance at a pixel from sample points read from depth and normal buffers. It processes dynamic scenes at HD 720p resolution in about 4.5 ms on Xbox 360 and 3 ms onNVIDIA GeForce580.
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    Simpler and Faster HLBVH with Work Queues
    (ACM, 2011) Garanzha, Kirill; Pantaleoni, Jacopo; McAllister, David; Carsten Dachsbacher and William Mark and Jacopo Pantaleoni
    A recently developed algorithm called Hierachical Linear Bounding Volume Hierarchies (HLBVH) has demonstrated the feasibility of reconstructing the spatial index needed forray tracing in real-time, even in the presence of millions of fully dynamic triangles. In this work we present a simpler and faster variant of HLBVH, where all the complex bookkeepingof pre x sums, compaction and partial breadth- rst tree traversal needed for spatial partitioning has been replaced with an elegant pipeline built on top of e cient work queues and binary search. The new algorithm is both faster and more memory e cient, removing the need for temporary storage of geometry data for intermediate computations. Finally, the same pipeline has been extended to parallelize the construction of the top-level SAH optimized tree on the GPU, eliminating round-trips to the CPU, accelerating the overall construction speed by a factor of 5 to 10x.
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    VoxelPipe: A Programmable Pipeline for 3D Voxelization
    (ACM, 2011) Pantaleoni, Jacopo; Carsten Dachsbacher and William Mark and Jacopo Pantaleoni
    We present a highly exible and e cient software pipeline for programmable triangle voxelization. The pipeline, entirely written in CUDA, supports both fully conservative and thinvoxelizations, multiple boolean, oating point, vector-typed render targets, user-de ned vertex and fragment shaders, and a bucketing mode which can be used to generate 3D A-bu ers containing the entire list of fragments belonging to each voxel. For maximum e ciency, voxelization is implemented as a sort-middle tile-based rasterizer, while the A-bu er mode, essentially performing 3D binning of triangles over uniform grids, uses a sort-last pipeline. Despite its major exibility, the performance of our tile-based rasterizer is always competitive with and sometimes more than an order of magnitude superior to that of state-of-the-artbinary voxelizers, whereas our bucketing system is up to 4 times faster than previous implementations. In both cases the results have been achieved through the use of carefulload-balancing and high performance sorting primitives.