Real‐Time Rendering of Wave‐Optical Effects on Scratched Surfaces

Abstract

The visual appearance of real‐world materials is characterized by surface features across many scales and has received significant attention by the graphics community for decades. Yet, even the most advanced microfacet models have difficulties faithfully recreating materials like snow, sand, brushed metal or hair that feature scale‐violating glints and speckles and defy any traditional notion of filtering and level of detail. In this work, we address an important subset of such materials, namely metal and dielectric surfaces that are covered with microscopic scratches, e.g., from polishing processes or surface wear. The appearance of such surfaces features fine‐scale spatial detail and iridescent colors caused by diffraction, and has only recently been successfully recreated. We adopt the scratch iridescence model, which is known for plausible results in offline Monte Carlo settings but unsuitable for real‐time applications where extensive illumination sampling is prohibitively expensive. In this paper, we introduce an efficient technique for incoherently integrating the contributions of individual scratches, as well as closed‐form solutions for modeling spherical and polygonal area light sources, and for the first time bring scratch iridescence within reach of real‐time applications.

Procedural Physically based BRDF for Real‐Time Rendering of Glints

“…We focus on the first term and review single-and multi-scale NDFs. Note that we do not review the many other, mainly specific representations, that are outside the scope of microfacet theory like for example scratches [RGB16,VWH18,WVJH17], point jittering in 3D grids [WB16], bi-directional texture functions [GK17] or data-driven techniques.…”

Real‐time Image‐based Lighting of Microfacet BRDFs with Varying Iridescence

“…Their approach delivers high-quality results, but is not suitable for real-time applications. Velinov et al [VWH18] provided a closed-form solution to this approach, which requires only a single sample per pixel and allows real-time performance. Yan et al [YHW * 18] described an approach for rendering specular geometry with high-frequency spatial surface variations modeled as height field.…”

Analytic Spectral Integration of Birefringence‐Induced Iridescence

“…A data driven approach is presented by [DTS∗14] where pre‐integrated look‐up tables are generated to allow real‐time rendering. Additional wave‐optics related work focuses on rendering glints [JHY∗14], modelling scratches in materials [RGB16; WVJH17; VWH18] and rendering diffractions that result from arbitrary micro‐scale structures in conductors and other materials [YHW∗18].…”