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 "Ray tracing"

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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.
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    Sampling from Quadric-Based CSG Surfaces
    (The Eurographics Association and John Wiley & Sons Ltd., 2021) Trettner, Philip; Kobbelt, Leif; Binder, Nikolaus and Ritschel, Tobias
    We present an efficient method to create samples directly on surfaces defined by constructive solid geometry (CSG) trees or graphs. The generated samples can be used for visualization or as an approximation to the actual surface with strong guarantees. We chose to use quadric surfaces as CSG primitives as they can model classical primitives such as planes, cubes, spheres, cylinders, and ellipsoids, but also certain saddle surfaces. More importantly, they are closed under affine transformations, a desirable property for a modeling system. We also propose a rendering method that performs local quadric ray-tracing and clipping to achieve pixel-perfect accuracy and hole-free rendering.