WGS84: World Geodesic System - revision dating from 1984

The World Geodesic System defines a reference frame for the earth, based on a reference geoid, using a reference ellipsoid.

WGS84 is a coordinate system, defining a reference frame for the earth, thanks to primary and secondary parameters :

  • primary parameters define the shape of the ellipsoid of the earth, its angular speed and its mass
  • secondary parameters define a detailed gravity model of the earth
Secondary parameters are necessary : WGS84 is used not only to define coordinates, but also to determine the orbit of the GPS navigation satellites.

GPS coordinates from a GPS receiver actually are a latitude, a longitude and an altitude calculated according to the WGS84 coordinate system.