What is the set of images of an object under all possible lighting conditions?

The appearance of a particular object depends on both the viewpoint from which it is observed and the light sources by which it is illuminated. If the appearance of two objects is never identical for any pose or lighting conditions, then { in theory { the objects can always be distinguished or recognized. The question arises: What is the set of images of an object under all lighting conditions and pose? In this paper, we consider only the set of images of an object under variable illumination (including multiple, extended light sources and attached shadows). We prove that the set of n-pixel images of a convex object with a Lambertian re ectance function, illuminated by an arbitrary number of point light sources at in nity, forms a convex polyhedral cone in IRn and that the dimension of this illumination cone equals the number of distinct surface normals. Furthermore, we show that the cone for a particular object can be constructed from three properly chosen images. Finally, we prove t...

• Type: Conference
• Year: 1996
• Where: CVPR
• Authors: Peter N. Belhumeur, David J. Kriegman
• Keywords: Computer Vision, CVPR 1996, Light Sources, Lighting Conditions, Particular Object