Near surface light source estimation from a single view image

Several techniques have been developed for estimating light source position in indoor or outdoor environment. However, those techniques assume that the light source can be approximated by a point, which cannot be applied safely to, for example, some case of Photometric Stereo reconstruction, when the light source is placed quite close to a small-size target, and hence the size of light source cannot be ignored. In this paper, we present a novel approach for estimating light source from single image of a scene that is illuminated by near surface light source. We propose to employ a shiny sphere and a Lambertion plate as light probe to locate light source position, where albedo variance of the Lambertian plate is used as the basis of the object function. We also illustrate the convexity of this object function and propose an efficient way to search the optimal value, i.e. source position. We test our calibration results on real images by means of Photometric Stereo reconstruction and image rendering, and both testing results show the accuracy of our estimation framework.