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Coordinate Reference Systems

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Coordinate Reference Systems

The ČÚZK domain is a guarantee of unification of geodetic controls of the Czech Republic realisation with up-to-date European geodetic controls realisation. Based on these steps, ČÚZK domain builds the georeferencing frame for accurate positioning of spatial data administered on the territory of the CR in both national coordinate systems and European systems that are binding for INSPIRE harmonised data.

The ČÚZK domain provides its own transformation service including a coordinate transformation web client for practical transformation between European Terrestrial Reference System 1989 (ETRS89) and the national Datum of Uniform Trigonometric Cadastral Network (S-JTSK). The ČÚZK domain furthermore provides its own transformation programs and approves transformation programs of third parties on the base of defined transformation methodology.

ČÚZK in such way provides to all data set administrators maintained in the S-JTSK datum guaranteed procedures for their transformation to ETRS89 with the highest accuracy usable for all spatial data administrated at the territory of the CR, including geodetic survey outputs.

Definition of coordinate reference system: Systems for uniquely referencing spatial information in space as a set of coordinates (x,y,z) and/or latitude and longitude and height, based on a geodetic horizontal and vertical datum.

The theme Coordinate Reference Systems is a reference theme for other INSPIRE themes. It shall not be published as a harmonised data set but is defines basic functionality that must be met by all spatial objects in other INSPIRE themes.

Spatial data shall be expressed in the ETRS89 datum, for network services in at least 2D geodetic datum (i.e. using Longitude and Latitude), whereas for their calculation ellipsoid GRS80 shall be used.

    To express ETRS89 datum in plane coordinates following projections are used:

  • Lambert Azimuthal Equal Area (ETRS89-LAEA)
  • Lambert Conformal Conic (ETRS89-LCC)
  • Transverse Mercator (ETRS89-TMzn)
If there is a need to express vertical component of the Earth's surface, the European Vertical Reference System (EVRS) shall be used.

Other systems can be defined as a part of the data specification.

Implementation in the ČÚZK Domain

The theme Coordinate Reference Systems is implemented in all network services for harmonised INSPIRE data sets that presently are provided in frame of ČÚZK Geoportal because the spatial data published in frame of these services meet especially following specifications:
  • The spatial data sets are expressed in the coordinate reference system ETRS89 in the form of at least two-dimensional geodetic coordinates (latitude, longitude).
  • Parameters of used coordinate reference system shall be defined in the common registry of coordinate systems - the EPSG Registry and the unique identifier of the projection / EPSG:4258 ETRS89 (geographic 2D) is declared.
Individual harmonised data set shall not be created for the theme Geographical Grid Systems because it is a reference theme, as described above.

The source for realisation of the theme at the territory is the data set geodetic controls that is not harmonised with INSPIRE but it contains information from geodetic controls that create the referencing frame of coordinate reference systems at the territory of the CR. The result of the theme realisation is coordinate transformation service of the ČÚZK Geoportal that is harmonised with INSPIRE and enables coordinate transformation into the ETRS89 datum at the territory of the CR.

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