Many real-world materials exhibit significant changes in appearance when rotated along a surface normal. Unfortunately, the reproduction of this behavior, often referred to as visual anisotropy, is for the sake of feasibility omitted in a number of material appearance measurement and modelling approaches. Contrary to analysis of isotropic materials, where locations of specular highlights can be predicted, the analysis of anisotropic ones is more challenging. The number and location of anisotropic highlights in angular space is unknown and thus depend entirely on the initial orientation of the measured material and on its optical properties. While recording of anisotropic appearance is crucial for realistic representation of materials, the related time- and resources-demanding measurement process remains one of the main CG challenges.
Similar challenge represents also a correct modelling of anisotropic appearance. The talk will describe our measurement approaches, methods for automatic identification of material's anisotropy, and finally we will show results of a novel approach to modelling of anisotropic BRDFs.