Cadastral Map Upgrading and Layers Harmonization for the Spatial Data Infrastructure in Friuli Venezia Giulia, Italy

The cadastral map represents an essential layer of any spatial data infrastructure, as well emphasized by the European directive INSPIRE. In this context, each cadastral parcel assumes a fundamental role, since it constitutes one of the key elements for carrying out an interoperable information system. The parcel represents the link among the legal domain information, the public restrictions, the private taxes, and further layers. The cadastral map, therefore, enlarges the required interoperable links to the complete available geo information tools like networks, plans, services and others. To fulfil this function, the cadastral map must satisfy a high level of accuracy, not reachable at the time of its implementation, often more than one century ago. Furthermore, the harmonization of a digital cadastral map into a spatial information system is complicated by further problems like fragmented reference systems, inaccurate upgrades, distorted and discontinuous representations. Accordingly, the cadastral map updating requires appropriate interventions. Sometimes the corrective actions prove to be empirical, not reproducible and of costly maintenance. Furthermore, the diversity of solutions hinders the database harmonization of the various administrations. This paper analyses the problems inherent in the Italian cadastral map, describes the methodology developed to update the digital map and recover the original geometric accuracy. Furthermore, the paper shows the results of a global and qualified set of interventions carried out by the Friuli Venezia Giulia regional administration, in cooperation with INSIEL Spa and the University of Udine, that make the cadastral data base fully harmonized and interoperable within the regional spatial data infrastructure.