A Discrete Polydisperse Anisotropic BSDF Model based on the Micrograin Framework
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Date
2026
Journal Title
Journal ISSN
Volume Title
Publisher
The Eurographics Association and John Wiley & Sons Ltd.
Abstract
We introduce a discrete polydisperse micrograin BSDF model for the rendering of porous surface materials composed of microscopic elements of different size, shape and reflectance distributed on a bulk medium. Our approach generalizes the anisotropic monodisperse micrograin model. We first reformulate it in a non-axis-aligned configuration, allowing for the later combination of different micrograin types elongated in arbitrary directions. We then extend the monodisperse model to the polydisperse case, deriving its three key components: (i) a general filling factor that controls the mix between micrograins and the bulk medium; (ii) an exact normal distribution function for surfaces composed of polydisperse micrograin distributions; and (iii) the corresponding fully-correlated shadowing and masking term. This results in an analytical single-scattering BSDF for discrete polydisperse surface materials, validated over ground truth simulations, for which we also derive a dedicated importance sampling procedure. Our model supports varying heights and anisotropy orientations of different micrograin types as input, giving additional control to simulate phenomena like retro-reflection from mixed materials, color mixture depending on lighting and observation directions, multiple directions of anisotropy, etc.
Description
CCS Concepts: Computing methodologies → Reflectance modeling
@article{10.1111:cgf.70387,
journal = {Computer Graphics Forum},
title = {{A Discrete Polydisperse Anisotropic BSDF Model based on the Micrograin Framework}},
author = {Xu, Kewei and Lucas, Simon and Ribardière, Mickael and Bringier, Benjamin and Barla, Pascal},
year = {2026},
publisher = {The Eurographics Association and John Wiley & Sons Ltd.},
ISSN = {1467-8659},
DOI = {10.1111/cgf.70387}
}
Citation
Computer Graphics Forum, Volume 45, Issue 2, e70387, 2026