Matching Real Fabrics with Micro-Appearance Models

Abstract

Micro-appearance models explicitly model the interaction of light with microgeometry at the fiber scale to produce realistic appearance. To effectively match them to real fabrics, we introduce a new appearance matching framework to determine their parameters. Given a micro-appearance model and photographs of the fabric under many different lighting conditions, we optimize for parameters that best match the photographs using a method based on calculating derivatives during rendering. This highly applicable framework, we believe, is a useful research tool because it simplifies development and testing of new models. Using the framework, we systematically compare several types of microappearance models. We acquired computed microtomography (micro CT) scans of several fabrics, photographed the fabrics under many viewing/ illumination conditions, and matched several appearance models to this data. We compare a new fiber-based light scattering model to the previously used microflake model. We also compare representing cloth microgeometry using volumes derived directly from the micro CT data to using explicit fibers reconstructed from the volumes. From our comparisons, we make the following conclusions: (1) given a fiber-based scattering model, volumeand fiber-based microgeometry representations are capable of very similar quality, and (2) using a fiber-specific scattering model is crucial to good results as it achieves considerably higher accuracy than prior work.

Fitting procedural yarn models for realistic cloth rendering

“…Although these models provide high-quality renderings for fabrics viewed from a distance, they lack the power to closely reproduce the appearance of fabrics with thick yarns or fuzzy silhouettes, or the generality to handle different fabrics with wildly varying appearances. Recent advances in cloth appearance modeling have led to the development of volumetric [Xu et al 2001;Jakob et al 2010;Zhao et al 2011;Zhao et al 2012;Zhao et al 2013] and fiber-based [Schröder et al 2015;Khungurn et al 2015] cloth models. Unlike traditional methods, they describe fabrics at 3D volumes with varying densities (volumetric) or collections of fiber curves (fiber-based).…”

“…Compared to traditional surface-based methods, these models are better at capturing the thickness and fuzziness of fabrics, which add significantly to their visual realism, and thus have brought the quality of computed rendered cloth to the next level. However, these techniques either provide automated creation of highly realistic models (achieved by measuring real-world samples) but carry little highlevel synthetic information (e.g., yarn twisting) [Zhao et al 2011;Khungurn et al 2015], or offer compact procedural representations but rely on manually configured models which require nontrivial parameter tweaking to match reality closely [Schröder et al 2015].…”

“…SIGGRAPH '16 Technical Paper, July 24 -28, 2016, Anaheim, CA, ISBN: 978-1-4503-4279-7/16/07 DOI: http://dx.doi.org/10.1145 Representing the richness of fabrics in virtual models has actively driven research in a variety of fabric appearance models. Recently, micro-appearance based fabric models [Zhao et al 2011;Zhao et al 2012;Khungurn et al 2015;Schröder et al 2015] that explicitly capture a fabric's micro-scale geometry have been introduced. Compared to traditional methods, these models describe fabrics at unprecedented detail, and thus offer superior generality as the complex appearance of a fabric is largely a direct consequence of its small-scale structures.…”

“…Previously, these detailed structures were measured through volume imaging (e.g., computed microtomography), leading to high-resolution 3D volumes [Zhao et al 2011;Zhao et al 2012] or large numbers of unorganized fiber curves [Khungurn et al 2015]. Neither of these representations is easy to manipulate.…”

CIECAM02 and Perception of Colour in 3D Computer Generated Graphics

“…Naprednejše metode vizualizacije tekstilij in oblačil vključujejo matematične modele videza oblačil (ang. cloth appearance model), ki jih na splošno delimo na površinske modele, volumetrične in eksplicitne modele [46].…”