Reference Ellipsoid Parameters of Cameroon from GPS Data

The standard spheroidalreference surface also referred as the reference ellipsoid is a part of mappingbasic infrastructures of a country. In Cameroon, the ellipsoid Clarke 1880 withunknown parameters used for a long time as reference system in basic mapping,has lead to the use of World Geodetic System 1984 (WGS 84) whose parameters arewell known. Meanwhile, the latter is not accurate locally due to the fact thatthe best ellipsoid is the one that fits very well with the local geoid. Inorder to look for the parameters of the local ellipsoid that fits best to thelocal geoid (Cameroon Geoid Model 2011 (CGM11)), the Global Positionning System(GPS) data made of 525 geodetic ground control points of the new geodeticnetwork of Cameroon set up in 2011 were used. These GPS measures provide foreach point the values of the ellipsoid height and the elevation which are usedto determine the parameters of the local ellipsoid model for Cameroon throughthe least square form of the Molodensky analytical method. The results are givenas the difference in ellipsoidal height relative to the parameters of the WGS84ellipsoid assuming the two ellipsoids in their parallel. These results showthat the obtained ellipsoid fits better to the local geoid with 1.072 m as thestandard deviation value, is improved considerably in comparison to theprevious studies conducted in Cameroon whose standard deviation was fairlyequal to 1.679 m.