Digital Map Rendering Method

The invention is a system and method of compressing terrain data to be used to render a three-dimensional map representation of the terrain data. In general, the invention operates by first selecting the boundaries of the terrain data and to be compressed and dividing the terrain data into regular geometric areas. Next, a type of free-edged, planar geometric surface is defined which is used to approximate the terrain data for each regular geometric area. The approximations are checked to determine if they fall within user selected tolerances. If the approximation for a specific regular geometric area is within the user specified tolerances, the data is saved for that specific regular geometric area. If the approximation for a specific regular geometric area falls outside the user specified tolerances, the regular geometric area is divided and a free-edged, planar geometric surface approximation is made for each of the divided areas. This process is recursively repeated until all of the regular geometric areas are approximated by free-edged, planar surfaces. Finally, the compressed terrain data is used to render a three-dimensional map.