36-Issue 4

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https://diglib.eg.org/handle/10.2312/2631440

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Browsing 36-Issue 4 by Subject "> Rendering"

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    Area-Preserving Parameterizations for Spherical Ellipses
    (The Eurographics Association and John Wiley & Sons Ltd., 2017) Guillén, Ibón; Ureña, Carlos; King, Alan; Fajardo, Marcos; Georgiev, Iliyan; López-Moreno, Jorge; Jarabo, Adrián; Zwicker, Matthias and Sander, Pedro
    We present new methods for uniformly sampling the solid angle subtended by a disk. To achieve this, we devise two novel area-preserving mappings from the unit square [0;1]2 to a spherical ellipse (i.e. the projection of the disk onto the unit sphere). These mappings allow for low-variance stratified sampling of direct illumination from disk-shaped light sources. We discuss how to efficiently incorporate our methods into a production renderer and demonstrate the quality of our maps, showing significantly lower variance than previous work.
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    Fiber-Level On-the-Fly Procedural Textiles
    (The Eurographics Association and John Wiley & Sons Ltd., 2017) Luan, Fujun; Zhao, Shuang; Bala, Kavita; Zwicker, Matthias and Sander, Pedro
    Procedural textile models are compact, easy to edit, and can achieve state-of-the-art realism with fiber-level details. However, these complex models generally need to be fully instantiated (aka. realized) into 3D volumes or fiber meshes and stored in memory, We introduce a novel realization-minimizing technique that enables physically based rendering of procedural textiles, without the need of full model realizations. The key ingredients of our technique are new data structures and search algorithms that look up regular and flyaway fibers on the fly, efficiently and consistently. Our technique works with compact fiber-level procedural yarn models in their exact form with no approximation imposed. In practice, our method can render very large models that are practically unrenderable using existing methods, while using considerably less memory (60-200 less) and achieving good performance.
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    Stochastic Light Culling for VPLs on GGX Microsurfaces
    (The Eurographics Association and John Wiley & Sons Ltd., 2017) Tokuyoshi, Yusuke; Harada, Takahiro; Zwicker, Matthias and Sander, Pedro
    This paper introduces a real-time rendering method for single-bounce glossy caustics created by GGX microsurfaces. Our method is based on stochastic light culling of virtual point lights (VPLs), which is an unbiased culling method that randomly determines the range of influence of light for each VPL. While the original stochastic light culling method uses a bounding sphere defined by that light range for coarse culling (e.g., tiled culling), we have further extended the method by calculating a tighter bounding ellipsoid for glossy VPLs. Such bounding ellipsoids can be calculated analytically under the classic Phong reflection model which cannot be applied to physically plausible materials used in modern computer graphics productions. In order to use stochastic light culling for such modern materials, this paper derives a simple analytical solution to generate a tighter bounding ellipsoid for VPLs on GGX microsurfaces. This paper also presents an efficient implementation for culling bounding ellipsoids in the context of tiled culling. When stochastic light culling is combined with interleaved sampling for a scene with tens of thousands of VPLs, this tiled culling is faster than conservative rasterization-based clustered shading which is a state-of-the-art culling technique that supports bounding ellipsoids. Using these techniques, VPLs are culled efficiently for completely dynamic single-bounce glossy caustics reflected from GGX microsurfaces.