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english:glossary:datum

Geodetic datum

A geodetic system, or geodetic datum, is “a modelling of the Earth to express geographical coordinates.”

It makes it possible to harmonize the information planned by a geocentric system (that is to say by angle measurements). This system is characterized by units of angles, in degrees, minutes, seconds, decimal degrees, grades or radians and is represented by a reference mark and an Ellipsoid associated with an original Meridian (Paris or Greenwich) . The world geodetic system is based on the global ellipsoid and is therefore less precise: WGS 84 (World Geodetic System 1984) ellipsoid IAG GGRS 80. The current French geodetic system is the RGF 93 with IAG GGRS 80 as reference ellipsoid. Historically, the French geodetic system was permanent (RGP), then that from the new French triangulation (NTF) set on the cross of the Pantheon in Paris with Clark 1880 as associate ellipsoid and the meridian of Paris.

(Source Wiki Georezo)
See : Coordinates (System of), Ellipsoid,Geodesy,Lambert93, Projection,WGS 84

english/glossary/datum.txt · Dernière modification : //27/11/2018 10:44// de thomas

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