RELIEF SHADING APPARATUS

摘要

A method and apparatus is described for placing shading on a map representation of a three dimensional surface. The shading is developed by scanning a three dimensional representation of the surface and following the instantaneous height of the part of the representation being scanned. A signal is generated from the rate of change of such height and caused to affect a sensitive surface to place shading on it in those areas which represent the sides of features on the map facing away from a chosen direction of supposed illumination of the surface.