geodetic coordinates

the geographical latitude and longitude of a point on the earth’s surface, determined by means of geodetic measurement of the distance (mainly by the method of triangulation) and the bearing (azimuth) from several other points whose geographic coordinates are known. Geodetic coordinates are calculated on the surface of a reference ellipsoid, which is a characterization of the shape and dimensions of the earth. They differ to a small degree from latitude and longitude as measured by astronomical methods, because of inaccuracies in the measurements of the adopted ellipsoid and deviations from the perpendicular. Along with the geodetic coordinates of a point, its altitude is also considered. It is calculated from the surface of the adopted reference ellipsoid and differs from its altitude above sea level by the size of its geoidal deviation from this ellipsoid.