An international reference system which was defined by the International Earth Rotation Service (IERS) and serves mainly for the international application of satellite geodesy and for defining the velocity of tectonic plates. ITRS is the «Conventional Terrestrial System» which is used as the basis for continental and national reference systems.
European reference systems
Besides the traditional national reference systems, there is a European reference system ETRS89. The connection of national reference systems to global, terrestrial reference systems by means of geodetic measuring methods results in only a limited accuracy. The modern (local) reference systems, however, distinguish themselves by a precisely defined link to global systems, allowing absolute positioning within a cm.
ITRS: IERS Terrestrial Reference System
ETRS89: European Terrestrial Reference System 1989
Reference system defined by the Subcommission EUREF of the International Association for Geodesy (IAG) in 1989. The scale and fundamental point are identical with the ITRS. Its spatial orientation was chosen in such a way that the system follows the movement of the Euro-asiatic tectonic plate and thus allows the determination of coordinates in Central and Northern Europe which are invariable in time in a first approximation.
Local European reference systems
Besides the European reference system ETRS89, older national systems are used in all European countries. For information on these systems and their transformation parameters, please consult with the national surveying institutions.
| Country | Reference system | Map projection | Info |
|---|---|---|---|
| CH / FL | CH1903 CH1903+ CHTRS95 (ETRS89) | Swiss Grid Swiss Grid UTM | swisstopo  |
| D | Potsdam (PD) DHRS (height) ED50 ETRS89 | TM (Gauss-Krüger, CM: 6, 9, 12° E) UTM | BKG |
| LVA BW | |||
| LVA Bayer | |||
| F | NTF RGF93 (ETRS89) | Lambert Conformal Conic (4 systems) | IGN |
| I | SI 40 ETRS89 | TM (Gauss-Boaga, CM: 9, 15° E) UTM | IGM |
| A | MGI ETRS89 | TM (Gauss-Krüger, CM: 28, 31, 34° E of Ferro UTM | BEV |
| others | European systems | CRS-EU | |
| global systems | EPSG |