Publisher Summary This chapter reviews current theoretical analyses of how human observers are able to determine the three-dimensional structures of objects and surfaces in the surrounding environment from statically presented patterns of light intensity. The amount of light that reflects from a surface in any given direction depends on a variety of physical variables including the orientation, roughness, and chemical composition of the surface, in addition to the positions and spectral compositions of the sources of illumination. The diffuse component of reflection refers to the light scattered equally in all directions. It originates from multiple surface reflections on a rough surface or from internal scattering when the incident light is able to penetrate beneath the surface. The intensity of diffusely reflected light at any given point of observation depends on the surface albedo and the angle of illumination. However, because the reflected light is scattered in all directions, its intensity is independent of viewing position. The models of static form perception have a variety of potential applications for facilitating pilot performance. This is particularly true for helicopter flight maneuvers in which the aircraft remains near ground level except for short periods of time when it must pop up for a brief glimpse of the surrounding terrain before returning to the relative safety of a more concealed position.