Measuring microstructures using confocal laser scanning microscopy for estimating surface roughness.

Realistic image synthesis is an important research goal in computer graphics. One important factor to achieve this goal is a bidirectional reflectance distribution function (BRDF) that mainly governs an appearance of an object. Many BRDF models have therefore been developed. A physically-based BRDF based on microfacet theory [Cook and Torrance 1982] is widely used in many applications since it can produce highly realistic images. The microfacetbased BRDF consists of three terms; a Fresnel, a normal distribution, and a geometric functions. There are many analytical and approximate models for each of these terms.