1. A method for determining a road surface of a landmark, the method comprising: reading, from a database, geometric data including a three-dimensional (3D) representation of the landmark; analyzing, via a processor, the geometric data to determine a largest continuous horizontal surface of the 3D representation of the landmark; and storing, via the processor, map data associated with the largest continuous horizontal surface to the database, wherein the map data indicates that the largest continuous horizontal surface comprises the road surface, and the map data is implemented by a vehicle navigation system to provide route guidance information for the road surface.