High-Performance Graphics 2019 - Short Papers

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Browsing High-Performance Graphics 2019 - Short Papers by Subject "Ray tracing"

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    Dynamic Many-Light Sampling for Real-Time Ray Tracing
    (The Eurographics Association, 2019) Moreau, Pierre; Pharr, Matt; Clarberg, Petrik; Steinberger, Markus and Foley, Tim
    Monte Carlo ray tracing offers the capability of rendering scenes with large numbers of area light sources-lights can be sampled stochastically and shadowing can be accounted for by tracing rays, rather than using shadow maps or other rasterizationbased techniques that do not scale to many lights or work well with area lights. Current GPUs only afford the capability of tracing a few rays per pixel at real-time frame rates, making it necessary to focus sampling on important light sources. While state-of-the-art algorithms for offline rendering build hierarchical data structures over the light sources that enable sampling them according to their importance, they lack efficient support for dynamic scenes. We present a new algorithm for maintaining hierarchical light sampling data structures targeting real-time rendering. Our approach is based on a two-level BVH hierarchy that reduces the cost of partial hierarchy updates. Performance is further improved by updating lower-level BVHs via refitting, maintaining their original topology. We show that this approach can give error within 6% of recreating the entire hierarchy from scratch at each frame, while being two orders of magnitude faster, requiring less than 1 ms per frame for hierarchy updates for a scene with thousands of moving light sources on a modern GPU. Further, we show that with spatiotemporal filtering, our approach allows complex scenes with thousands of lights to be rendered with ray-traced shadows in 16.1 ms per frame.
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    Mach-RT: A Many Chip Architecture for Ray Tracing
    (The Eurographics Association, 2019) Vasiou, Elena; Shkurko, Konstantin; Brunvand, Erik; Yuksel, Cem; Steinberger, Markus and Foley, Tim
    We propose an unconventional solution to high-performance ray tracing that combines a ray ordering scheme that minimizes access to the scene data with a large on-chip buffer acting as near-compute storage that is spread over multiple chips. We demonstrate the effectiveness of our approach by introducing Mach-RT (Many chip - Ray Tracing), a new hardware architecture for accelerating ray tracing. Extending the concept of dual streaming, we optimize the main memory accesses to a level that allows the same memory system to service multiple processor chips at the same time. While a multiple chip solution might seem to imply increased energy consumption as well, because of the reduced memory traffic we are able to demonstrate, performance increases while maintaining reasonable energy usage compared to academic and commercial architectures.
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    Real-Time Ray Tracing on Head-Mounted-Displays for Advanced Visualization of Sheet Metal Stamping Defects
    (The Eurographics Association, 2019) Dietrich, Andreas; Wurster, Jan; Kam, Eric; Gierlinger, Thomas; Steinberger, Markus and Foley, Tim
    Although interactive ray tracing has been around since the late 1990s, real-time frame rates had so far only been feasible for low and mid-size screen resolutions. Recent developments in GPU hardware, that specifically accelerate ray tracing, make it possible for the first time to target head-mounted displays (HMDs), which require constant high frame rates as well as high resolution images for each eye. This allows for utilizing ray tracing algorithms in novel virtual reality scenarios, which are impractical to do with rasterization. In this short paper we present our experiences of applying real-time ray tracing to the problem of detecting cosmetic defects in sheet metal stamping simulations by creating a virtual light cage.
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    Wide BVH Traversal with a Short Stack
    (The Eurographics Association, 2019) Vaidyanathan, Karthik; Woop, Sven; Benthin, Carsten; Steinberger, Markus and Foley, Tim
    Compressed wide bounding volume hierarchies can significantly improve the performance of incoherent ray traversal, through a smaller working set of inner nodes and therefore a higher cache hit rate. While inner nodes in the hierarchy can be compressed, the size of the working set for a full traversal stack remains a significant overhead. In this paper we introduce an algorithm for wide bounding volume hierarchy (BVH) traversal that uses a short stack of just a few entries. This stack can be fully stored in scarce on-chip memory, which is especially important for GPUs and dedicated ray tracing hardware implementations. Our approach in particular generalizes the restart trail algorithm for binary BVHs to BVHs of arbitrary widths. Applying our algorithm to wide BVHs, we demonstrate that the number of traversal steps with just five stack entries is close to that of a full traversal stack. We also propose an extension to efficiently cull leaf nodes when a closer intersection has been found, which reduces ray primitive intersections by up to 14%.