39-Issue 4

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https://diglib.eg.org/handle/10.2312/2632924

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Browsing 39-Issue 4 by Subject "Ray tracing"

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    Adaptive Matrix Completion for Fast Visibility Computations with Many Lights Rendering
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Wang, Sunrise; Holzschuch, Nicolas; Dachsbacher, Carsten and Pharr, Matt
    Several fast global illumination algorithms rely on the Virtual Point Lights framework. This framework separates illumination into two steps: first, propagate radiance in the scene and store it in virtual lights, then gather illumination from these virtual lights. To accelerate the second step, virtual lights and receiving points are grouped hierarchically, for example using Multi- Dimensional Lightcuts. Computing visibility between clusters of virtual lights and receiving points is a bottleneck. Separately, matrix completion algorithms reconstruct completely a low-rank matrix from an incomplete set of sampled elements. In this paper, we use adaptive matrix completion to approximate visibility information after an initial clustering step. We reconstruct visibility information using as little as 10%to 20%samples for most scenes, and combine it with shading information computed separately, in parallel on the GPU. Overall, our method computes global illumination 3 or more times faster than previous stateof- the-art methods.
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    Neural Denoising with Layer Embeddings
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Munkberg, Jacob; Hasselgren, Jon; Dachsbacher, Carsten and Pharr, Matt
    We propose a novel approach for denoising Monte Carlo path traced images, which uses data from individual samples rather than relying on pixel aggregates. Samples are partitioned into layers, which are filtered separately, giving the network more freedom to handle outliers and complex visibility. Finally the layers are composited front-to-back using alpha blending. The system is trained end-to-end, with learned layer partitioning, filter kernels, and compositing. We obtain similar image quality as recent state-of-the-art sample based denoisers at a fraction of the computational cost and memory requirements.
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    Photorealistic Material Editing Through Direct Image Manipulation
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Zsolnai-Fehér, Károly; Wonka, Peter; Wimmer, Michael; Dachsbacher, Carsten and Pharr, Matt
    Creating photorealistic materials for light transport algorithms requires carefully fine-tuning a set of material properties to achieve a desired artistic effect. This is typically a lengthy process that involves a trained artist with specialized knowledge. In this work, we present a technique that aims to empower novice and intermediate-level users to synthesize high-quality photorealistic materials by only requiring basic image processing knowledge. In the proposed workflow, the user starts with an input image and applies a few intuitive transforms (e.g., colorization, image inpainting) within a 2D image editor of their choice, and in the next step, our technique produces a photorealistic result that approximates this target image. Our method combines the advantages of a neural network-augmented optimizer and an encoder neural network to produce high-quality output results within 30 seconds. We also demonstrate that it is resilient against poorly-edited target images and propose a simple extension to predict image sequences with a strict time budget of 1-2 seconds per image.
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    A Scalable and Production Ready Sky and Atmosphere Rendering Technique
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Hillaire, Sébastien; Dachsbacher, Carsten and Pharr, Matt
    We present a physically based method to render the atmosphere of a planet from ground to space views. Our method is cheap to compute and, as compared to previous successful methods, does not require any high dimensional Lookup Tables (LUTs) and thus does not suffer from visual artifacts associated with them. We also propose a new approximation to evaluate light multiple scattering within the atmosphere in real time. We take a new look at what it means to render natural atmospheric effects, and propose a set of simple look up tables and parameterizations to render a sky and its aerial perspective. The atmosphere composition can change dynamically to match artistic visions and weather changes without requiring heavy LUT update. The complete technique can be used in real-time applications such as games, simulators or architecture pre-visualizations. The technique also scales from power-efficient mobile platforms up to PCs with high-end GPUs, and is also useful for accelerating path tracing.