From: Real-world illumination and the perception of surface reflectance properties Journal of Vision. 2003;3(5):3. doi:10.1167/3.5.3 Figure Legend: Illumination at a point in space is defined as the set of rays that converge on that point from every direction. The set of all rays forms a spherical image of incoming light such that each location on the sphere represents the amount of light arriving from the corresponding direction. Such spherical images can be acquired photographically for points in the real world. (a) shows one such map, acquired by Debevec et al. (2000). (b) shows the same illumination map projected onto a two-dimensional plane. Real-world illumination maps exhibit statistical regularities similar to those of conventional real-world images. Date of download: 10/20/2017 The Association for Research in Vision and Ophthalmology Copyright © 2017. All rights reserved.