An Adaptive BRDF Fitting Metric. (20th July 2020)

• Record Type: Journal Article
• Authors: Bieron, J.; Peers, P.
• Is Part Of: Computer graphics forum. Volume 39:Number 4(2020)
• Page Start: 59
• Page End: 74
• Publication Date: 2020-07-20
• Subjects: Isotropic BRDF -- fitting -- image‐driven; Computer graphics -- Periodicals; 006.605
• DOI: 10.1111/cgf.14054
• Languages: English
• ISSNs: 0167-7055

Abstract

Abstract: We propose a novel image‐driven fitting strategy for isotropic BRDFs. Whereas existing BRDF fitting methods minimize a cost function directly on the error between the fitted analytical BRDF and the measured isotropic BRDF samples, we also take into account the resulting material appearance in visualizations of the BRDF. This change of fitting paradigm improves the appearance reproduction fidelity, especially for analytical BRDF models that lack the expressiveness to reproduce the measured surface reflectance. We formulate BRDF fitting as a two‐stage process that first generates a series of candidate BRDF fits based only on the BRDF error with measured BRDF samples. Next, from these candidates, we select the BRDF fit that minimizes the visual error. We demonstrate qualitatively and quantitatively improved fits for the Cook‐Torrance and GGX microfacet BRDF models. Furthermore, we present an analysis of the BRDF fitting results, and show that the image‐driven isotropic BRDF fits generalize well to other light conditions, and that depending on the measured material, a different weighting of errors with respect to the measured BRDF is necessary.