*2.1. Open Spatial Data*

This paper focuses on the possibility of using open spatial data using the example of data that is available in the authors' country of residence, Poland. This section is a characterisation of open spatial data available in Poland which were used in the research, i.e., orthophotomaps and cadastral data—The Land and Building Register (hereinafter: EGiB). The use of OpenStreetMap (hereinafter: OSM) resource was also considered, but it was ultimately abandoned for reasons described in the next section.

Open spatial data in Poland are available on the basis of individual laws and European regulations concerning spatial information infrastructure, including the Inspire Directive [25]. The data are made available through the Geoportal [26] which is maintained by the Head Office of Geodesy and Cartography, or through individual local governmen<sup>t</sup> units. The list of maintained resources is available at [27]. These units are obliged to maintain and make available free of charge (usually in an incomplete form for reasons of personal data protection and legal interests) geodetic resources, including those concerning the cadastre—EGiB. However, these resources are currently under development and are not ye<sup>t</sup> available nationwide in a downloadable form.

The resources are maintained in various coordinate systems. Most often, data from the national dataset (e.g., orthophotomaps) are provided in the PL1992 system (EPSG 2180), while data from local governmen<sup>t</sup> units (e.g., EGiB) are provided in the PL2000 system (EPSG 2176-2179—depending on the zone).
