Shape recovery of hybrid reflectance surface using neural network

The main interest of previous researches for shape from shading was only on a Lambertian surface which consists of a diffuse reflectance surface. In practice, natural objects have hybrid reflectance, which limits the recovery of shape from intensity distribution. In this paper, we propose the method of determining shape using a neural network and diffuse illumination. The segmented region of sphere surface is used for a training set, which can be determined by shadow line and edge of surface. Diffuse illumination is used to avoid specular spike and highlight which usually cause many problems such as intensity disparities. The diffuse illumination method using flat paper allows us to reduce these phenomena with a simple scheme. The neural network and diffuse illumination method are useful for shape from shading, because it can be applied to objects of unknown reflectance properties, but it is applied only to Torrance-Sparrow style reflectance