Orthophotomosaic of Slovakia

The vast majority of decisions made within public administration have a spatial aspect. For this reason, it is essential that the public administration has accurate, reliable and up-to-date spatial data. In view of the rapidly changing landscape, mainly due to human activity, spatial data needs to be collected and updated using methods that are highly efficient, effective and fast. Such methods also include airborne imagery which results are processed into digital orthophotographs or orthophotomosaic. In view of the above, the Ministry of Agriculture and Rural Development of the Slovak Republic and the Geodesy, Cartography and Cadastre Authority of the Slovak Republic agreed on joint cooperation in the creation of the Orthophotomosaic of the Slovak Republic. Subordinate organizations - National Forest Centre (NLC) and Geodetic and Cartographic Institute Bratislava (GKÚ) were entrusted with this implementation. The first production cycle of the orthophotomosaic was completed in 2020.

The second production cycle (2020 - 2022) of the Orthophotomosaic was finished in 2023.  The airborne imagery was taken in the western part of Slovakia in 2020, in the central part of Slovakia in 2021 and in the eastern part of Slovakia in 2022.

Orthophotomosaic in web application Map client ZBGIS:

• How to work with Orthophotomosaic in QGIS application (Slovak only)
• How to connect georeferenced rasters to application Bentley MicroStation V8i (Slovak only)
• How to connect georeferenced rasters to application Kokeš (Slovak only)
• How to convert raster from format RGBN to RGB in IrfanView (Slovak only)

Overview of the division of Orthophotomosaics of the Slovak Republic 2nd cycle (2020-2022) RGB-NIR variant in ZIP files for download

Overview of the division of Orthophotomosaics of the Slovak Republic 2nd cycle (2020-2022) RGB variant in ZIP files for download

Data of a smaller extent, up to 20 map sheets, are freely downloadable through the Map Client ZBGIS application. More information HERE. Orthophotomosaic data shall be subject to the Terms and conditions of provision and use of Orthtophotomosaic.

Overview of airborne imageries, from which Orthophotomosaic of Slovakia 2020-2022 (2^nd cycle) was created, together with the exact date of their creation is available in ESRI Shapefile format for download HERE.

Orthophotomosaic map sheet layout
Orthophotomosaic map sheet layout (administrative borders exluded)

Parameters (2^nd cycle):
GSD (Ground Sampling Distance): 20 cm/pixel
Format:  TIFF + TFW
Number of channels: 4 (RGBN, 8-bit)
Coordinate reference system: S-JTSK(JTSK) - EPSG code:5514
Number of map sheets (MS) in 1:5000 scale: territory of western Slovakia =  3418 MS, territory of central Slovakia =  3435 MS, territory of eastern Slovakia =  3422 MS

Accuracy (2^nd cycle):
Root mean square error:
RMSExy = 0,21 m

CE95 (Circular error 95%):
CE95 = 1,7308 x RMSExy = 0,36 m

CE95 value defines the radius of a circle centred at the specified point on the orthophotomosaic within which the real horizontal position of the point is located with 95% probability. It represents the magnitude of an error which will not be exceeded in 95% of cases.