way humans do with their eyes. By using two images, they can get a 3-dimensional perspective of objects on the surface like we do. See also Photometric stereo Photogrammetry Stereoscopy Bump mapping References Further reading Kirk, Randolph L., Barrett, Janet M., Soderblom, Laurence A. (2003) Photoclinometry Made Simple...? Advances in Planetary Mapping. External links Shape from Shading - Photoclinometry USGS Geomatics Photographic processes