New simple model improves light reflections on rough surfaces
An Elementary Expression for Multiple Scattering in Homogeneous Microflake Media
Graphics
Summary
When light bounces off rough surfaces like frosted glass or tiny flakes, it can scatter in complicated ways. The authors found a simple formula that accurately describes how light bounces multiple times inside such materials. This formula is easy to calculate and helps make computer-generated images look more realistic. Their model smoothly changes from rough diffuse reflection to shiny mirror-like reflection depending on the angle you look at the surface.
What this means in practice
- •For graphics programmers: Create more accurate and efficient shaders that simulate complex reflections on microflake materials in computer graphics.
- •For optical engineers: Model scattering properties of homogeneous microflake media more precisely to improve the design of optical devices involving layered materials.
Authors
Jonathan Dupuy
Abstract
We derive a novel diffuse-like BRDF based on microfacet theory. Its main novelty lies in the fact that it admits an elementary expression for both evaluation and importance sampling, while accounting exactly for all scattering orders under the Smith shadowing assumption. As such, it is the first to settle the question of whether such a construction was possible. In practice, the BRDF produces Lambertian reflectance at normal incidence and progressively concentrates reflected light around the mirror direction as incidence approaches grazing. We showcase this effect by comparing rendering results against Lambertian and state-of-the-art stochastic microfacet BRDFs.