Glint Rendering based on a Multiple-Scattering Patch BRDF
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Date
2019
Journal Title
Journal ISSN
Volume Title
Publisher
The Eurographics Association and John Wiley & Sons Ltd.
Abstract
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].
Description
@article{10.1111:cgf.13767,
journal = {Computer Graphics Forum},
title = {{Glint Rendering based on a Multiple-Scattering Patch BRDF}},
author = {Chermain, Xavier and Claux, Frédéric and Mérillou, Stéphane},
year = {2019},
publisher = {The Eurographics Association and John Wiley & Sons Ltd.},
ISSN = {1467-8659},
DOI = {10.1111/cgf.13767}
}