ACM Transactions on Graphics (Proceedings of ACM SIGGRAPH 2007), 26(3):77:1-77:9, July 2007.
Visual observation is our principal source of information in determining the nature of objects, including shape, material or roughness. The physiological and cognitive processes that resolve visual input into an estimate of the material of an object are influenced by the illumination and the shape of the object. This affects our ability to select materials by observing them on a point-lit sphere, as is common in current 3D modeling applications. In this paper we present an exploratory psychophysical experiment to study various influences on material discrimination in a realistic setting. The resulting data set is analyzed using a wide range of statistical techniques. Analysis of variance is used to estimate the magnitude of the influence of geometry, and fitted psychometric functions produce significantly diverse material discrimination thresholds across different shapes and materials. Suggested improvements to traditional material pickers include direct visualization on the target object, environment illumination, and the use of discrimination thresholds as a step size for parameter adjustments.
