40-Issue 8

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https://diglib.eg.org/handle/10.2312/2633076

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Browsing 40-Issue 8 by Subject "Rendering"

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    A Halfedge Refinement Rule for Parallel Catmull-Clark Subdivision
    (The Eurographics Association and John Wiley & Sons Ltd., 2021) Dupuy, Jonathan; Vanhoey, Kenneth; Binder, Nikolaus and Ritschel, Tobias
    We show that Catmull-Clark subdivision induces an invariant one-to-four refinement rule for halfedges that reduces to simple algebraic expressions. This has two important consequences. First, it allows to refine the halfedges of the input mesh, which completely describe its topology, concurrently in breadth-first order. Second, it makes the computation of the vertex points straightforward as the halfedges provide all the information that is needed. We leverage these results to derive a novel parallel implementation of Catmull-Clark subdivision suitable for the GPU. Our implementation supports non-quad faces, extraordinary vertices, boundaries and semi-sharp creases seamlessly. Moreover, we show that its speed scales linearly with the number of processors, and yields state-of-the-art performances on modern GPUs.
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    ReSTIR GI: Path Resampling for Real-Time Path Tracing
    (The Eurographics Association and John Wiley & Sons Ltd., 2021) Ouyang, Yaobin; Liu, Shiqiu; Kettunen, Markus; Pharr, Matt; Pantaleoni, Jacopo; Binder, Nikolaus and Ritschel, Tobias
    Even with the advent of hardware-accelerated ray tracing in modern GPUs, only a small number of rays can be traced at each pixel in real-time applications. This presents a significant challenge for path tracing, even when augmented with state-of-the art denoising algorithms. While the recently-developed ReSTIR algorithm [BWP*20] enables high-quality renderings of scenes with millions of light sources using just a few shadow rays at each pixel, there remains a need for effective algorithms to sample indirect illumination. We introduce an effective path sampling algorithm for indirect lighting that is suitable to highly parallel GPU architectures. Building on the screen-space spatio-temporal resampling principles of ReSTIR, our approach resamples multi-bounce indirect lighting paths obtained by path tracing. Doing so allows sharing information about important paths that contribute to lighting both across time and pixels in the image. The resulting algorithm achieves a substantial error reduction compared to path tracing: at a single sample per pixel every frame, our algorithm achieves MSE improvements ranging from 9.3x to 166x in our test scenes. In conjunction with a denoiser, it leads to high-quality path traced global illumination at real-time frame rates on modern GPUs.