Browsing by Author "Chermain, Xavier"

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    Glint Rendering based on a Multiple-Scattering Patch BRDF
    (The Eurographics Association and John Wiley & Sons Ltd., 2019) Chermain, Xavier; Claux, Frédéric; Mérillou, Stéphane; Boubekeur, Tamy and Sen, Pradeep
    Rendering materials such as metallic paints, scratched metals and rough plastics requires glint integrators that can capture all micro-specular highlights falling into a pixel footprint, faithfully replicating surface appearance. Specular normal maps can be used to represent a wide range of arbitrary micro-structures. The use of normal maps comes with important drawbacks though: the appearance is dark overall due to back-facing normals and importance sampling is suboptimal, especially when the micro-surface is very rough. We propose a new glint integrator relying on a multiple-scattering patch-based BRDF addressing these issues. To do so, our method uses a modified version of microfacet-based normal mapping [SHHD17] designed for glint rendering, leveraging symmetric microfacets. To model multiple-scattering, we re-introduce the lost energy caused by a perfectly specular, single-scattering formulation instead of using expensive random walks. This reflectance model is the basis of our patch-based BRDF, enabling robust sampling and artifact-free rendering with a natural appearance. Additional calculation costs amount to about 40% in the worst cases compared to previous methods [YHMR16,CCM18].