Microfacet theory for non-uniform heightfields
SIGGRAPH 2023 (Conference Track)

Abstract
We propose new methods for combining NDFs in microfacet theory, enabling a wider range of surface statistics. The new BSDFs that follow allow for independent adjustment of appearance at grazing angles, and can't be represented by linear blends of single-NDF BSDFs. We derive importance sampling for a symmetric operator that blends NDFs uniformly, and introduce a new asymmetric operator that supports NDF variation with elevation. We also extend Smith's model to support piecewise-constant NDF and material variations with elevation, and demonstrate accuracy via Monte Carlo simulations.NVIDIA project page
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BibTeX Reference
@inproceedings{dEon2023NonuniformMicrofacets,
author = {d'Eon, Eugene and Bitterli, Benedikt and Weidlich, Andrea and Zeltner, Tizian},
title = {Microfacet theory for non-uniform heightfields},
year = {2023},
publisher = {Association for Computing Machinery},
address = {New York, NY, USA},
doi = {10.1145/3588432.3591486},
booktitle = {SIGGRAPH 2023 Conference Papers},
numpages = {10},
location = {Los Angeles, CA, USA}
}