OpenStreetMap for cadastral purposes: an application using VGI for official processes in urban areas

The scope of the paper is to test if the online dynamic maps such as the OpenStreetMap (OSM) can be used for official mapping projects such as Cadastre, to investigate the advantages and the concerns of online and open to the public procedures and to identify those differentiations between experts and amateurs that play a critical role in such official projects. The specific research is focused on the use of OSM in urban areas as an alternative method to the official cadastral surveys. This paper presents the possibilities and the perspectives of OSM for spatial and attribute cadastral data collection and storage for the compilation of draft cadastral maps as an alternative methodology within the terms of the volunteered geographic information (VGI). The authors carried out a practical experiment in an extended part of the historic city centre of Athens and updated the online dynamic map of OSM with attribute and spatial cadastral data. Surveying students explored the capacities of the dynamic map in two steps: (a) in a section where the polygons of the buildings already existed on the map, they had to improve it with attribute data, and (b) in another section where no relevant polygons existed, a spatial and attribute data enhancement was required. The research was based on the various approaches that each student adopted and the freedom that the OSM offers to the users. The results show that users can easily distinguish the differences in capacities between the OSM and the commercial software; the inexpensive, easy to use and quick methodology of the OSM in contrast to the accurate, authoritative and assured methodology of the commercial software.