Optimizing BRDF orientations for the manipulation of anisotropic highlights

• Published in: Computer graphics forum Vol. 33; no. 2; pp. 313 - 321
• Main Authors: Raymond, Boris, Guennebaud, Gaël, Barla, Pascal, Pacanowski, Romain, Granier, Xavier
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.05.2014; Wiley
• Subjects: Analysis; Anisotropy; Categories and Subject Descriptors (according to ACM CCS); Computer graphics; Computer programs; Computer Science; Digital video; Editing; Graphics; I.3.3 [Computer Graphics]: Picture/Image Generation-Display algorithms; I.3.4 [Computer Graphics]: Graphics Utilities-Paint systems; Inspiration; Interactive; Optimization; Orientation; Solvers; Studies; Tangents
• ISSN: 0167-7055; 1467-8659
• DOI: 10.1111/cgf.12300

This paper introduces a system for the direct editing of highlights produced by anisotropic BRDFs, which we call anisotropic highlights. We first provide a comprehensive analysis of the link between the direction of anisotropy and the shape of highlight curves for arbitrary object surfaces. The gained insights provide the required ingredients to infer BRDF orientations from a prescribed highlight tangent field. This amounts to a non‐linear optimization problem, which is solved at interactive framerates during manipulation. Taking inspiration from sculpting software, we provide tools that give the impression of manipulating highlight curves while actually modifying their tangents. Our solver produces desired highlight shapes for a host of lighting environments and anisotropic BRDFs.