Defining Parameters:
WGS 84 identifies four defining parameters.
These are
- The semi-major axis of the WGS 84 ellipsoid,
- the flattening factor of the Earth,
- the nominal mean angular velocity of the Earth, and
- the geocentric gravitational constant as specified below.
Note :
- WGS84 is realised by adopting the coordinates of stations around the world surveyed by Doppler satellite surveying technique.
- The origin of WGS84 is located at the Earth center with an uncertainty of 1 to 2 meters.
ACCURACY OF WGS 84 COORDINATES
Numerous techniques now exist to establish WGS 84 coordinates for a given site. The accuracy and precision achieved by these various techniques vary significantly. The most common, currently-available techniques are listed below:
