Learning generative models for rendering specular microgeometry

Abstract

from synthetic or measured examples, by training a generative adversarial network (GAN). A key challenge in applying GAN synthesis to spatially varying BRDFs is evaluating the reflectance for a single location and direction without the cost of evaluating the whole hemisphere. We resolve this using a novel method for partial evaluation of the generator network. We are also able to control large-scale spatial texture using a conditional GAN approach. The benefits of our approach include the ability to synthesize spatially large results without repetition, support for learning from measured data, and evaluation performance independent of the complexity of the dataset synthesis or measurement. CCS Concepts: • Computing methodologies → Rendering.

A practical ply-based appearance model of woven fabrics

“…Micro-geometry models. Rendering glints on micro-geometry surfaces liked brushed metal shares some of the complexity seen with bundles of fibers in cloth rendering [Iwasaki et al 2012;Kuznetsov et al 2019;Raymond et al 2016;Wu et al 2011Wu et al , 2013. These methods have not been used for the fiber structures seen in clothing, but the ideas could likely be extended to increase the efficiency of highly detailed cloth models.…”

Computing the Bidirectional Scattering of a Microstructure Using Scalar Diffraction Theory and Path Tracing

“…GHS theory is considered in the single scattering BRDF models by Holzschuch and Pacanowski [HP17] and Yan et al [YHW∗18]. The term from wave optics corresponding to the shadowing and masking from geometric optics is similar but not exactly the same [BNM15; WYH∗18; KHZ∗19]. To the best of our knowledge, it is unknown to what extent ray traced shadowing and masking in combination with the original Kirchhoff approximation (as suggested by Sancer [San69]) compares with results obtained with GHS theory.…”

“…We can thus use Eq. (13) or one of the other models from previous work [DWMG15; WVJH17; YHW∗18; KHZ∗19] for computing the complex amplitude of the reflected wave.…”

“…Scalar diffraction theory is frequently used in the modeling of reflectance functions [Kaj85; HTSG91; Sta99; DWMG15; HP17; WVJH17; YHW∗18; KHZ∗19]. This is especially the case when it comes to rendering of scratched or brushed metallic surfaces or glinty surfaces in general.…”

“…We consider explicitly defined microgeometry instead of the popular normal distribution function maps [DWMG15; YHMR16; YHW∗18; KHZ∗19]. This enables us to account for shadowing and masking without the simplifications imposed by an analytic geometric attenuation term like the often used Smith approximation [Smi67].…”