ILLUMINATION RECOVERY FROM IMAGES WITH CAST SHADOWS

Abstract

The effects produced in an image by cast shadows can be quite complex, especially when light comes from all directions. This makes it difficult to recover the illumination from a scene and recognize objects from the images. In this paper, we show that such images can be well approximated using much simpler lighting represented by a combination of low frequency spherical harmonics, and a small number of directional sources. Therefore, the illumination of the scene can be recovered by summing the spherical harmonic lighting and a small number of directional light sources. To demonstrate the effectiveness of the proposed method, we have successfully tested it by using sets of synthesized images rendered by directional light sources or environment maps with different objects.