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Reference system as basis for coordinates

The reference system forms the theoretical basis for calculating coordinates. For this purpose the measurement units, zero point and position of the coordinates system have to be defined. In the reference system the type of map projection is also specified that is to be used for depicting the spherical earth on a map. There are global, European and Swiss reference systems.

The components of a reference system include:

  • A coordinates system with zero point, coordinate axes and measurement unit
  • The type of map projection by means of which a given region can be optimally depicted on a map.

There are global as well as national reference systems. The most widely used global reference system is the World Geodetic System (WGS84), which comprises longitudes and latitudes. Many countries (including Switzerland) have defined their own national reference systems. The official Swiss reference system is called «CH1903+». The designation «CH1903+» refers to the reference system that was introduced in Switzerland in 1903 and was updated during the 1990s. Switzerland also has a reference system called «CHTRS95» (Swiss Terrestrial Reference System 1995) which is used for scientific purposes

Map projection

Have you ever tried to flatten an orange peel in one piece? This is not possible without causing the peel to split apart. The same problem applies when attempting to depict the spherical earth on a flat surface like a map. With the aid of map projection, a specific region (e.g. a country) can be depicted on a map with a minimum of distortion. The method used in Switzerland is called conformal, oblique cylinder projection.  

Oblique, conformal cylinder projection
Oblique, conformal cylinder projection

Based on this method, a grid of rectangular intersecting lines (the coordinates network) is incorporated into the Swiss national maps. These lines facilitate the determination of coordinates on the maps.

Extract from the 1:xx,xxx national map with coordinates
Extract from the 1:xx,xxx national map with coordinates


Federal Office of Topography swisstopo Seftigenstrasse 264
P.O. Box
3084 Wabern
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+41 58 469 01 11

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Relevant authority

Geodesy and Federal Directorate of Cadastral Surveying
E-mail

Federal Office of Topography swisstopo

Seftigenstrasse 264
P.O. Box
3084 Wabern

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