Browsing by Author "Shirley, Peter"

Now showing 1 - 3 of 3
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    Practical Product Sampling by Fitting and Composing Warps
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Hart, David; Pharr, Matt; Müller, Thomas; Lopes, Ward; McGuire, Morgan; Shirley, Peter; Dachsbacher, Carsten and Pharr, Matt
    We introduce a Monte Carlo importance sampling method for integrands composed of products and show its application to rendering where direct sampling of the product is often difficult. Our method is based on warp functions that operate on the primary samples in [0;1)^n, where each warp approximates sampling a single factor of the product distribution. Our key insight is that individual factors are often well-behaved and inexpensive to fit and sample in primary sample space, which leads to a practical, efficient sampling algorithm. Our sampling approach is unbiased, easy to implement, and compatible with multiple importance sampling. We show the results of applying our warps to projected solid angle sampling of spherical triangles, to sampling bilinear patch light sources, and to sampling glossy BSDFs and area light sources, with efficiency improvements of over 1.6 x on real-world scenes.
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    A Taxonomy of Bidirectional Scattering Distribution Function Lobes for Rendering Engineers
    (The Eurographics Association, 2020) McGuire, Morgan; Dorsey, Julie; Haines, Eric; Hughes, John F.; Marschner, Steve; Pharr, Matt; Shirley, Peter; Klein, Reinhard and Rushmeier, Holly
    We propose a taxonomy and terminology for rendering engineers to use in describing the main categories of mathematical lobes that are combined to implement bidirectional scattering distribution functions (BSDFs). Bringing consistent language to this area will increase clarity in API names, textbooks, and scholarly publications. We developed this taxonomy and terminology for consistency across our own upcoming works. The taxonomy corresponds to the major BSDF implementation branches in a renderer, rather than surface appearance, and is consistent with physical considerations. The terminology aligns as closely as possible with previous work in rendering and adjacent fields, while resolving inconsistencies among them. The taxonomy is not intended for art direction, machine vision research, optics, material/lighting engineering, or other areas where the critical distinctions between materials differ from those needed by a renderer.
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    Visualizing Errors in Rendered High Dynamic Range Images
    (The Eurographics Association, 2021) Andersson, Pontus; Nilsson, Jim; Shirley, Peter; Akenine-Möller, Tomas; Theisel, Holger and Wimmer, Michael
    A new error metric targeting rendered high dynamic range images is presented. Our method computes a composite visualization over a number of low dynamic range error maps of exposure compensated and tone mapped image pairs with automatically computed, or manually provided, parameters. We argue that our new error maps predict errors substantially better than metrics previously used in rendering. Source code is released with the hope that our work can be a useful tool for future research.