43-Issue 4

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https://diglib.eg.org/handle/10.2312/3607013

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Browsing 43-Issue 4 by Subject "CCS Concepts: Computing methodologies → Reflectance modeling"

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    Neural Appearance Model for Cloth Rendering
    (The Eurographics Association and John Wiley & Sons Ltd., 2024) Soh, Guan Yu; Montazeri, Zahra; Garces, Elena; Haines, Eric
    The realistic rendering of woven and knitted fabrics has posed significant challenges throughout many years. Previously, fiberbased micro-appearance models have achieved considerable success in attaining high levels of realism. However, rendering such models remains complex due to the intricate internal scatterings of hundreds of fibers within a yarn, requiring vast amounts of memory and time to render. In this paper, we introduce a new framework to capture aggregated appearance by tracing many light paths through the underlying fiber geometry. We then employ lightweight neural networks to accurately model the aggregated BSDF, which allows for the precise modeling of a diverse array of materials while offering substantial improvements in speed and reductions in memory. Furthermore, we introduce a novel importance sampling scheme to further speed up the rate of convergence. We validate the efficacy and versatility of our framework through comparisons with preceding fiber-based shading models as well as the most recent yarn-based model.
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    Practical Appearance Model for Foundation Cosmetics
    (The Eurographics Association and John Wiley & Sons Ltd., 2024) Lanza, Dario; Padrón-Griffe, Juan Raúl; Pranovich, Alina; Muñoz, Adolfo; Frisvad, Jeppe Revall; Jarabo, Adrian; Garces, Elena; Haines, Eric
    Cosmetic products have found their place in various aspects of human life, yet their digital appearance reproduction has received little attention. We present an appearance model for cosmetics, in particular for foundation layers, that reproduces a range of existing appearances of foundation cosmetics: from a glossy to a matte to an almost velvety look. Our model is a multilayered BSDF that reproduces the stacking of multiple layers of cosmetics. Inspired by the microscopic particulates used in cosmetics, we model each individual layer as a stochastic participating medium with two types of scatterers that mimic the most prominent visual features of cosmetics: spherical diffusers, resulting in a uniform distribution of radiance; and platelets, responsible for the glossy look of certain cosmetics.We implement our model on top of the position-free Monte Carlo framework, that allows us to include multiple scattering. We validate our model against measured reflectance data, and demonstrate the versatility and expressiveness of our model by thoroughly exploring the range of appearances that it can produce.
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    VMF Diffuse: A Unified Rough Diffuse BRDF
    (The Eurographics Association and John Wiley & Sons Ltd., 2024) d'Eon, Eugene; Weidlich, Andrea; Garces, Elena; Haines, Eric
    We present a practical analytic BRDF that approximates scattering from a generalized microfacet volume with a von Mises- Fischer NDF. Our BRDF seamlessly blends from smooth Lambertian, through moderately rough height fields with Beckmannlike statistics and into highly rough/porous behaviours that have been lacking from prior models. At maximum roughness, our model reduces to the recent Lambert-sphere BRDF. We validate our model by comparing to simulations of scattering from geometries with randomly-placed Lambertian spheres and show an improvement relative to a rough Beckmann BRDF with very high roughness.