Light reflection models for computer graphics have been developed over the past several decades. For real paint surfaces, it is possible to model their bidirectional reflectance distribution function with simple models. This research established a framework to evaluate two simple reflection models, Phong and Torrance-Sparrow, which were used to render artist paint surfaces under different illumination angles. An image acquisition system was set up to capture the images under selected illuminated angles. The parameters of the specular and the diffuse components were estimated with these image sequences. At the evaluation stage, both physical-based metrics and psychophysical techniques were used to evaluate the estimation accuracy of each model. For both methods, the comparison of the estimations of two models showed that better estimations were obtained from the Torrance-Sparrow model for the glossy samples. The estimation accuracies of two models are almost the same for the matte samples. In addition, the numbers of illumination angles of the test samples can be minimized based on both mathematical calculations and psychophysical experiments.
Ying Chen, Roy S. Berns, Lawrence A. Taplin, "Model Evaluation for Computer Graphics Renderings of Artist Paint Surfaces" in Proc. IS&T 15th Color and Imaging Conf., 2007, pp 54 - 59, https://doi.org/10.2352/CIC.2007.15.1.art00011