Patent ID: 7908045

Claim:
A system for presenting an image of terrain on a display unit of an aircraft, said system comprising: a navigation system for acquiring navigation data representative of aircraft position, aircraft altitude, and direction of flight; a terrain database storing terrain data comprised of a plurality of terrain cells, wherein each terrain cell comprises data representative of the highest elevation and location of such terrain cell; a terrain image processor, electronically coupled to receive the navigation data and the terrain data, where such processor receives the navigation data, defines at least one range of terrain elevations based upon the aircraft altitude, wherein each range of terrain elevations is associated with one terrain threat level, and each terrain threat level is associated with a range of aircraft altitudes, retrieves terrain data from the terrain database based upon each defined range of terrain elevations, the aircraft position, and the direction of flight, where the retrieval of such terrain data is limited to each terrain cell located in front of the aircraft in which the highest elevation falls within any of the defined range or ranges of terrain elevations, determines the terrain threat level associated with each terrain cell of the retrieved terrain data, and provides terrain image data to an indicating system, where such terrain image data is representative of the location and the terrain threat level associated with each terrain cell of the retrieved terrain data; and the indicating system, electronically coupled to receive the terrain image data, where such system receives the terrain image data, and presents at least one terrain symbol representative of the terrain image data on a display unit, such that each terrain symbol is an identically-shaped closed shape representative of a single terrain threat level, where at least one terrain threat level is represented by a transparent terrain symbol, and the entire perimeter of each closed shape is visually-delineated, where such visual delineation is maintained when contiguous terrain cells are presented.