Rendering - Experimental Ideas & Implementations 2016

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https://diglib.eg.org/handle/10.2312/15442

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Browsing Rendering - Experimental Ideas & Implementations 2016 by Subject "Raytracing"

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    Node Culling Multi-Hit BVH Traversal
    (The Eurographics Association, 2016) Gribble, Christiaan; Elmar Eisemann and Eugene Fiume
    We introduce node culling multi-hit BVH traversal to enable faster multi-hit ray tracing in a bounding volume hierarchy (BVH). Existing, widely used ray tracing engines expose API features that enable implementation of multi-hit traversal without modifying their underlying-and highly optimized-BVH construction and traversal routines; however, this approach requires naive multi-hit traversal to guarantee correctness. We evaluate two low-overhead, minimally invasive, and flexible API mechanisms that enable node culling implementation entirely with user-level code, thereby leveraging existing BVH construction and traversal routines. Results show that node culling offers potentially significant improvement in multi-hit performance in a BVH for cases in which users request fewer-than-all hits.
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    Subdivision Next-Event Estimation for Path-Traced Subsurface Scattering
    (The Eurographics Association, 2016) Koerner, David; Novak, Jan; Kutz, Peter; Habel, Ralf; Jarosz, Wojciech; Elmar Eisemann and Eugene Fiume
    We present subdivision next-event estimation (SNEE) for unbiased Monte Carlo simulation of subsurface scattering. Our technique is designed to sample high frequency illumination through geometrically complex interfaces with highly directional scattering lobes enclosing a scattering medium. This case is difficult to sample and a common source of image noise. We explore the idea of exploiting the degree of freedom given by path vertices within the interior medium to find two-bounce connections to the light that satisfy the law of refraction. SNEE first finds a surface point by tracing a probe ray and then performs a subdivision step to place an intermediate vertex within the medium according to the incoming light at the chosen surface point. Our subdivision construction ensures that the path will connect to the light while obeying Fermat's principle of least time. We discuss the details of our technique and demonstrate the benefits of integrating SNEE into a forward path tracer.