Introduction to the Swiss geographic coordinate system (Switzerland coordinate system or Swiss Grid)

The Swiss geographic coordinate system (CH1903 standard) is a set of geographic coordinate systems for mapping and related geographic research in Switzerland. The coordinate system was developed by the Swiss Federal Topography Bureau (SWISSTOPO). The map projection method used by the Swiss geographic coordinate system (projection) is oblique Mercator based on 1841 Bessel ellipsoid. 1841 Bessel ellipsoid is still used by a handful of European countries, including Switzerland, but now most of the world is using the new satellite ellipsoid.

Why use the Swiss geographic coordinate system? Or what does the existence of the Swiss geographic coordinate system mean? First, the Swiss geographic coordinate system stipulates that each point on the map (longitude, latitude) is expressed in meters, and people have a much stronger sense of distance than latitude and longitude in "M" units. Second, the geographical location of Switzerland determines that the coordinates of all points in Switzerland are positive, and that the longitude coordinates are always greater than the north latitude coordinate values, so that in many cases the error can be avoided. Finally, Switzerland's land area is relatively small, more suitable for the use of the coordinate system, if China also uses the same coordinate system, in the location can be a lot of difficult to handle the situation, for example, because of China's large land area, resulting in geographical coordinates of the value is too large, the calculation of overhead increase.

The base reference point selected by the Swiss geographic coordinate system (CH1903 standard) is the coordinates of the site of the Bern Observatory at Bern University (46°57′3.9″n 7°26′ 19.1″e (WGS84)). In order to avoid the error caused by the coordinate conversion, CH1903 the base reference point coordinates as (600000m e,200000m N). where e represents east longitude and N represents north latitude. The origin coordinates of the CH1903 are located near Bordeaux, France. The ch1903+ standard is to improve and improve the CH1903 standard, the former chooses the new basic reference point of Zimmerwald observation station coordinates, but the former ensures the consistency of the coordinate with the latter as much as possible. The maximum error of ch1903+ and CH1903 is within 3 meters, which is usually not noticeable for non-precision map services.

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Introduction to the Swiss geographic coordinate system (Switzerland coordinate system or Swiss Grid)