1. A system for presenting a monochrome image of terrain on a head-up display unit, such system comprising: a source for providing navigation data; a source for providing terrain data; an image generating processor configured to receive navigation data corresponding to aircraft position and orientation; receive terrain data from a database, where the terrain data corresponds to the navigation data; generate an image data set as a function of the terrain data and color intensity data, where the image data set is representative of a non-wireframe, single color perspective of the terrain scene outside the aircraft, where the perspective has the visual appearance of a three-dimensional, lighted solid terrain image formed by varying the brightness of the single color, and the color intensity data is comprised of shading effect data, such that changes in terrain elevation or terrain contours are indicated by varied brightnesses of the single color, whereby darker and lighter areas of the three-dimensional, lighted solid terrain image comprised of the varied brightnesses correlate to greater and lesser transparencies of a head-up display unit, respectively; and provide the image data set to the head-up display unit; and the head-up display unit configured to receive the image data set, and display the perspective represented in the image data set.