Spatial properties of light fields in natural scenes

Light fields [Gershun 1939] of natural scenes are highly complex and vary within a scene from point to point. However, in many applications complex lighting can be successfully replaced by its low order approximation [Ramamoorthi and Hanrahan 2001]. The purpose of this research was to investigate the spatial behavior of light fields in natural scenes. We describe the light fields in terms of spherical harmonics and analyze their qualitative properties. We show that low order approximations of natural light fields vary smoothly and systematically, in accordance with very simple models. This finding has important implications for graphics, visualization, architectural design and scene perception research.