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

Accurate postal code maps have many applications within GIS as the postal code has the potential to link the address description of buildings to their location in a specified global reference system in a more natural way. This relationship is possible in both directions: geocoding and reverse-geocoding. These operators demand a mechanism for 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 can be used as the linkage. This paper describes the procedure, based on the Dutch cadastral registration, to obtain a reliable 6-position (i.e., 2628BX, the highest level of detail possible) planar postal code map for the Netherlands. Problems with existing, Voronoi-diagram based, postal code maps, like intersected houses and arbitrary derived (and thus unrecognizable) boundaries are avoided. The reliability of the derived planar postal code map is discussed and results are illustrated by figures. For a planar coverage, non built-up parcels having no postal code should be assigned a plausible postal code. Furthermore special attention is given to infrastructural parcels. These parcels are divided at their (approximated) skeletons first and then these subdivided infrastructure parcels are piecewise attached to their neighbour parcels. This new approach results in very reliable postal code maps, which are visually attractive too as infrastructure lines can be recognized. 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. Also a number of non-implemented alternatives or improvements are given.