Usage
The ellipsoid data published by Bessel (1841) were then the best and most modern data mapping the Earth's figure. They were used by almost all national surveys. Some surveys in Asia switched to the Clarke ellipsoid of 1880. After the arrival of the geophysical reduction techniques many projects used other examples such as the Hayford ellipsoid of 1910 which was adopted in 1924 by the International Association of Geodesy (IAG) as the International ellipsoid 1924. All of them are influenced by geophysical effects like vertical deflection, mean continental density, rock density and the distribution of network data. Every reference ellipsoid deviates from the worldwide data (e.g. of satellite geodesy) in the same way as the pioneering work of Bessel.
In 1950 about 50% of the European triangulation networks and about 20% of other continents networks were based on the Bessel ellipsoid. In the following decades the American states switched mainly to the Hayford ellipsoid 1908 ("internat. Ell. 1924") which was also used for the European unification project ED50 sponsored by the USA after World War II. Russia forced its satellite states in Eastern Europe to use the Krassowski ellipsoid of about 1940.
As of 2010 the Bessel ellipsoid is the geodetic system for Germany, for Austria and the Czech Republic. It is also used partly in the successor states of Yugoslavia and some Asian countries: Sumatra & Borneo, Belitung, Okinawa (Japan) and Africa in Eritrea and Namibia.
Read more about this topic: Bessel Ellipsoid
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