High-Performance Graphics 2021 - Symposium Papers

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Browsing High-Performance Graphics 2021 - Symposium Papers by Subject "Rendering"

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    Rearchitecting Spatiotemporal Resampling for Production
    (The Eurographics Association, 2021) Wyman, Chris; Panteleev, Alexey; Binder, Nikolaus and Ritschel, Tobias
    Recent work by Bitterli et al. [BWP*20] introduced a real-time, many-light algorithm for rendering dynamic direct illumination from millions of lights by iteratively applying resampled importance sampling using weighted reservoir sampling. While enabling new levels of lighting complexity in real-time, the total cost remained beyond the budgets of even the most computationally demanding games. We introduce key algorithmic improvements developed while productizing this method that collectively reduce lighting costs by up to 7x, dramatically improve memory coherence, shrink the required ray budget, increase rendering quality, and expose parameters that enable trading quality for performance.
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    Transfer-Function-Independent Acceleration Structure for Volume Rendering in Virtual Reality
    (The Eurographics Association, 2021) Faludi, Balázs; Zentai, Norbert; Zelechowski, Marek; Zam, Azhar; Rauter, Georg; Griessen, Mathias; Cattin, Philippe C.; Binder, Nikolaus and Ritschel, Tobias
    Visualizing volumetric medical datasets in a virtual reality environment enhances the sense of scale and has a wide range of applications in diagnostics, simulation, training, and surgical planning. To avoid motion sickness, rendering at the native refresh rate of the head-mounted display is important, and frame drops have to be avoided. Despite these strict requirements and the high computational complexity of direct volume rendering, it is feasible to provide a comfortable experience using volume ray casting on modern hardware. Many implementations use precomputed gradients or illumination to achieve the targeted frame rate, and most rely on acceleration structures, such as distance maps or octrees, to speed up the ray marching shader. With many of these techniques, the opacity of voxels is baked into the precomputed data, requiring a recomputation when the opacity changes. This makes it difficult to implement features that lead to a sudden change in voxel opacity, such as real-time transfer function editing, transparency masking, or toggling the visibility of segmented tissues. In this work, we present an empty space skipping technique using an octree that does not have to be recomputed when the transfer function is changed and performs well even when more complex transfer functions are used. We encode the content of the volume as bitfields in the octree and are able to skip empty areas, even with transfer functions that cannot efficiently be represented as a simple range of voxel values. We show that our approach allows arbitrarily editing of the transfer function in real-time while maintaining the target frame rate of 90 Hz.
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    Vertex-Blend Attribute Compression
    (The Eurographics Association, 2021) Kuth, Bastian; Meyer, Quirin; Binder, Nikolaus and Ritschel, Tobias
    Skeleton-based animations require per-vertex attributes called vertex-blend attributes. They consist of a weight tuple and a bone index tuple. With meshes becoming more complex, vertex-blend attributes call for compression. However, no technique exists that exploits their special properties. To this end, we propose a novel and optimal weight compression method called Optimal Simplex Sampling and a novel bone index compression. For our test models, we compress bone index tuples between 2.3:1 and 3.5:1 and weight tuples between 1.6:1 and 2.5:1 while being visually lossless. We show that our representations can speed rendering and reduces GPU memory requirements over uncompressed representations with a similar error. Further, our representations compress well with general-purpose codecs making them suitable for offline-storage and streaming.