EGPGV16: Eurographics Symposium on Parallel Graphics and Visualization

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https://diglib.eg.org/handle/10.2312/15271

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Browsing EGPGV16: Eurographics Symposium on Parallel Graphics and Visualization by Subject "Distributed/network graphics"

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    Dynamically Scheduled Region-Based Image Compositing
    (The Eurographics Association, 2016) Grosset, A. V. Pascal; Knoll, Aaron; Hansen, Charles; Enrico Gobbetti and Wes Bethel
    Algorithms for sort-last parallel volume rendering on large distributed memory machines usually divide a dataset equally across all nodes for rendering. Depending on the features that a user wants to see in a dataset, all the nodes will rarely finish rendering at the same time. Existing compositing algorithms do not often take this into consideration, which can lead to significant delays when nodes that are compositing wait for other nodes that are still rendering. In this paper, we present an image compositing algorithm that uses spatial and temporal awareness to dynamically schedule the exchange of regions in an image and progressively composite images as they become available. Running on the Edison supercomputer at NERSC, we show that a scheduler-based algorithm with awareness of the spatial contribution from each rendering node can outperform traditional image compositing algorithms.
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    High-Performance Mesh Partitioning and Ghost Cell Generation for Visualization Software
    (The Eurographics Association, 2016) Biddiscombe, John; Enrico Gobbetti and Wes Bethel
    Post-processing large datasets efficiently in parallel requires good load balancing of geometry supplied to the visualization pipeline. When datasets are not pre-partitioned or cannot be read back from simulation output in well controlled pieces, it is necessary to perform a partitioning step before certain algorithms may be applied. Spatially sensitive operations such as resampling, smoothing or certain field advection/stencil algorithms require datasets/meshes to be contiguous and provide ghost cells so that artefacts do not occur at process boundaries where discontinuities occur. This paper presents an integration of the mesh partitioning library Zoltan, into the Visualization Toolkit framework, VTK and the parallel visualization tool ParaView. The implementation allows seamless generation of well partitioned datasets using a user provided weighting and a selection of ghost cell generation options. The algorithms, and results obtained with the partitioning classes are presented with representative use cases that show an order of magnitude increase in performance compared to the off-the-shelf partitioning available previously, improving performance and reducing memory consumption/duplication.