Browsing by Author "Ahmed, Abdalla G. M."

Now showing 1 - 6 of 6
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    Analysis of Sample Correlations for Monte Carlo Rendering
    (The Eurographics Association and John Wiley & Sons Ltd., 2019) Singh, Gurprit; Ă–ztireli, Cengiz; Ahmed, Abdalla G. M.; Coeurjolly, David; Subr, Kartic; Deussen, Oliver; Ostromoukhov, Victor; Ramamoorthi, Ravi; Jarosz, Wojciech; Giachetti, Andrea and Rushmeyer, Holly
    Modern physically based rendering techniques critically depend on approximating integrals of high dimensional functions representing radiant light energy. Monte Carlo based integrators are the choice for complex scenes and effects. These integrators work by sampling the integrand at sample point locations. The distribution of these sample points determines convergence rates and noise in the final renderings. The characteristics of such distributions can be uniquely represented in terms of correlations of sampling point locations. Hence, it is essential to study these correlations to understand and adapt sample distributions for low error in integral approximation. In this work, we aim at providing a comprehensive and accessible overview of the techniques developed over the last decades to analyze such correlations, relate them to error in integrators, and understand when and how to use existing sampling algorithms for effective rendering workflows.
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    Capacity Constrained Voronoi Tessellation Revisited
    (The Eurographics Association, 2017) Ahmed, Abdalla G. M.; Deussen, Oliver; Tao Ruan Wan and Franck Vidal
    Capacity Constrained Voronoi Tessellation is an important concept that greatly influenced recent research on point sampling. The original concept was based on discretizing the sampled domain, and the algorithm was prohibitively slow, even with some proposed accelerations. We present a few improvements that make a real difference in the speed of the algorithm, bringing it back into presence.
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    Colored AA Bitmaps
    (The Eurographics Association, 2017) Ahmed, Abdalla G. M.; Deussen, Oliver; Tao Ruan Wan and Franck Vidal
    AA Bitmaps are ornamental monochrome bitmaps. We present an algorithm for colorizing a certain family of AA Bitmaps that relies on modular arithmetics.
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    Continuous-Line-Based Halftoning with Pinwheel Tiles
    (The Eurographics Association, 2020) Ahmed, Abdalla G. M.; Ritsos, Panagiotis D. and Xu, Kai
    We describe a technique for continuous-line-based halftoning with space-filling curves, namely Segerman's pinwheel curve, which is based on Conway's pinwheel tiles. We adapt the length of the curve passing through the tiles in accordance with a supplied density map, e.g. a grayscale image. We use the subdivision depth of the tiling for a coarse control of the curve length, and we describe a finer control to faithfully match the density map. Our technique exhibits excellent temporal coherence, making it suitable for animated images.
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    Sampling with Pinwheel Tiles
    (The Eurographics Association, 2019) Ahmed, Abdalla G. M.; Vidal, Franck P. and Tam, Gary K. L. and Roberts, Jonathan C.
    We outline an adaptive sampling framework based on Conway's pinwheel tiles. It offers a unique feature that the generated tiles have infinite number of orientation angles, minimizing the strong auto-correlations found on all other lookup-sampling frameworks. We describe a novel string-based approach to enumerate distinct neighbor configurations in pinwheel tiles.
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    Voronoi Tree Maps with Circular Boundaries
    (The Eurographics Association, 2018) Ahmed, Abdalla G. M.; {Tam, Gary K. L. and Vidal, Franck
    Voronoi tree maps are an important milestone in information visualization, representing a substantial advancement of the original tree maps concept. We address a less-studied variant of Voronoi tree maps that uses multiplicative-weighted Voronoi diagrams. We highlight the merits of this variant, and discuss the difficulties that might have discouraged further exploration, proposing insights for overcoming these difficulties.