Determining Reflectance and Light Position from a Single Image Without Distant Illumination Assumption

Abstract

Several techniques have been developed for recovering reflectance properties of real surfaces under unknown illu-mination conditions. However, in most cases, those tech-niques assume that the light sources are located at inifin-ity, which cannot be applied to, for example, photometric modeling of indoor environments. In this paper, we pro-pose two methods to estimate the surface reflectance prop-erty of an object, as well as the position of a light source from a single image without the distant illumination as-sumption. Given a color image of an object with specular reflection as an input, the first method estimates the light source position by fitting to the Lambertian diffuse compo-nent, while separating the specular and diffuse components by using an iterative relaxation scheme. Moreover, we ex-tend the above method by using a single specular image as an input, thus removing its constraints on the diffuse re-flectance property and the number of light sources. This method simultaneously recovers the reflectance properties and the light source positions by optimizing the linearity of a log-transformed Torrance-Sparrow model. By estimating the object’s reflectance property and the light source posi-tion, we can freely generate synthetic images of the target object under arbitrary source directions and source-surface distances. 1.