Fast-MSX: Fast Multiple Scattering Approximation
Enrique Rosales, Fatemeh Teimury, Joshua Horacsek, Aria Salari, Xuebin Qin, Adi Bar-Lev, Xiaoqiang Zhe, Ligang Liu · 2023
Classical microfacet theory suffers from energy loss on materials with high roughness due to the single bounce assumption of most microfacet models. When roughness is high, there is a large chance of multiple scattering occurring among the microfacets of the surface. Without explicitly modelling for this behaviour, rough surfaces appear darker than they should. To address this issue, we present a novel method to estimate the multiple scattering contribution from a second light bounce. Our method is inspired by Zipin’s geometric construction approach, which simplifies the calculation of the light transport inside a V-groove cavity. Our experimental results demonstrate that our method is visually pleasing, physically plausible, and artifact-free compared to recent multiple scattering works. Additionally, the low computational cost makes our model suitable for real-time rendering.