Construction of the planar partition postal code map ased on cadastral registration

Accurate postal code maps could play an important role within GIS as the postal code has the potential to link the address description of buildings and their location in a certain global reference system. This relationship is possible in both directions: address matching and geocoding. These operators demand a certain mechanism in translating an exact geometric position (i.e. WGS84 coordinate) into a location indication (town, street, house number) and vice versa. As most built-up parcels are provided with a postal code this indicator could be used as the linkage. This paper describes the procedure, based on the Dutch cadastral registration, to obtain a reliable 6-position planar postal code map for the Netherlands. Problems with existing postal code maps, like intersecting of houses and arbitrary derived boundaries are avoided. For a planar coverage, non built-up parcels having no assigned postal code should be assigned a plausible postal code. Therefore special attention is given to infrastructural parcels. These parcels are divided at their skeleton first and then piecewise attached to their neighbor parcels. This new approach results in very reliable postal code maps, which are visually attractive too as infrastructure lines can be regognized. The procedure is generic and can be applied to other administrative parcel information as well. The algorithm is implemented using the Computational Geometry Algorithms Library (CGAL), and the possibilities and limitations of this library are addressed as well. The reliability of the derived planar postal code map is discussed and some results are shown by figures. A short overview of alternatives and improvements concludes this paper.