The (official) reference frame of GPS is the World Geodetic System 1984 (WGS-84). When using GPS, the coordinates of terrestrial sites, for example, are obtained in the same reference frame. The surveyor is not, usually, interested in coordinates of the terrestrial points referring to a global frame; rather, the results are preferred in a local coordinate frame either as geodetic (i.e., ellipsoidal) coordinates, as plane coordinates, or as vectors combined with other terrestrial data. Since the WGS-84 is a geocentric system and the local system usually is not, certain transformations are required. The subsequent sections deal with the transformations most frequently used.
KeywordsZenith Angle Geoidal Height Universal Transverse Mercator Orthometric Height Fiducial Point
Unable to display preview. Download preview PDF.