High-Performance Graphics 2016

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https://diglib.eg.org/handle/10.2312/15439

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Browsing High-Performance Graphics 2016 by Subject "Color"

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    Filtering Distributions of Normals for Shading Antialiasing
    (The Eurographics Association, 2016) Kaplanyan, Anton S.; Hill, Stephen; Patney, Anjul; Lefohn, Aaron; Ulf Assarsson and Warren Hunt
    High-frequency illumination effects, such as highly glossy highlights on curved surfaces, are challenging to render in a stable manner. Such features can be much smaller than the area of a pixel and carry a high amount of energy due to high reflectance. These highlights are challenging to render in both offline rendering, where they require many samples and an outliers filter, and in real-time graphics, where they cause a significant amount of aliasing given the small budget of shading samples per pixel. In this paper, we propose a method for filtering the main source of highly glossy highlights in microfacet materials: the Normal Distribution Function (NDF). We provide a practical solution applicable for real-time rendering by employing recent advances in light transport for estimating the filtering region from various effects (such as pixel footprint) directly in the parallel-plane half-vector domain (also known as the slope domain), followed by filtering the NDF over this region. Our real-time method is GPU-friendly, temporally stable, and compatible with deferred shading, normal maps, as well as with filtering methods for normal maps.
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    Infinite Resolution Textures
    (The Eurographics Association, 2016) Reshetov, Alexander; Luebke, David; Ulf Assarsson and Warren Hunt
    We propose a new texture sampling approach that preserves crisp silhouette edges when magnifying during close-up viewing, and benefits from image pre-filtering when minifying for viewing at farther distances. During a pre-processing step, we extract curved silhouette edges from the underlying images. These edges are used to adjust the texture coordinates of the requested samples during magnification. The original image is then sampled-only once!-with the modified coordinates. The new technique provides a resolution-independent image representation capable of billions of texels per second on a mid-range graphics card.
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    Photon Splatting Using a View-Sample Cluster Hierarchy
    (The Eurographics Association, 2016) Moreau, Pierre; Sintorn, Erik; Kämpe, Viktor; Assarsson, Ulf; Doggett, Michael; Ulf Assarsson and Warren Hunt
    Splatting photons onto primary view samples, rather than gathering from a photon acceleration structure, can be a more efficient approach to evaluating the photon-density estimate in interactive applications, where the number of photons is often low compared to the number of view samples. Most photon splatting approaches struggle with large photon radii or high resolutions due to overdraw and insufficient culling. In this paper, we show how dynamic real-time diffuse interreflection can be achieved by using a full 3D acceleration structure built over the view samples and then splatting photons onto the view samples by traversing this data structure. Full dynamic lighting and scenes are possible by tracing and splatting photons, and rebuilding the acceleration structure every frame. We show that the number of view-sample/photon tests can be significantly reduced and suggest further culling techniques based on the normal cone of each node in the hierarchy. Finally, we present an approximate variant of our algorithm where photon traversal is stopped at a fixed level of our hierarchy, and the incoming radiance is accumulated per node and direction, rather than per view sample. This improves performance significantly with little visible degradation of quality.