Abstract: The moving map composer (MMC) is a device that allows a user to manipulate different sources of map data into a single map for presentation on a display. The MMC has an ability to extract a predetermined area of map coverage defined by sets of latitude and longitude points, or non-orthogonal areas of map coverage, the smallest of which is a segment. A bitmap is a representation of an available map coverage for a given area selected by a user having a “set”, or “1” bit to indicate a segment is present, and a “clear”, or “0” bit to indicate a segment is missing. The size of the bitmap is determined dynamically to assure a two-bit buffer zone of clear bits around a polygon's maximum extent. If the user selected polygon crosses one or more maps, the polygon is subdivided into several new polygons.