geodetic datum overview orientation of the coordinate system and additional information.Datum Transformations of GPS Positions Application Note Clearer notes on converting ECEF coordinates to WGS-84 datum.ECEF datum transformation Notes on converting ECEF coordinates to WGS-84 datum."Modern Terrestrial Reference Systems (Part 1)" (PDF). United Nations Office for Outer Space Affairs. "World Geodetic System 1984 datasheet" (PDF). ^ National Geospatial Intelligence Agency.^ "OGC Abstract Specification Topic 2: Referencing by coordinates Corrigendum".American Institute of Aeronautics & Astronautics. Archived from the original (PDF) on April 18, 2015. See " Geodetic system." Using Bowring's formula in 1976 Survey Review the first iteration gives latitude correct within 10 -11 degree as long as the point is within 10,000 meters above or 5,000 meters below the ellipsoid. The reverse conversion is harder: given X-Y-Z we can immediately get longitude, but no closed formula for latitude and height exists. Given the dimensions of the ellipsoid, the conversion from lat/lon/height-above-ellipsoid coordinates to X-Y-Z is straightforward-calculate the X-Y-Z for the given lat-lon on the surface of the ellipsoid and add the X-Y-Z vector that is perpendicular to the ellipsoid there and has length equal to the point's height above the ellipsoid. The Y axis is also in the plane of the equator, passing through extending from 90°W longitude (negative) to 90☎ longitude (positive)Īn example is the NGS data for a brass disk near Donner Summit, in California.The X axis is in the plane of the equator, passing through the origin and extending from 180° longitude (negative) to the prime meridian (positive) in WGS 84, this is the IERS Reference Meridian.
In WGS 84, this is the international reference pole (IRP), which does not exactly coincide with the Earth's rotational axis The slight "wobbling" of the rotational axis is known as polar motion, and can actually be measured against an ECEF. The Z axis is the line between the North and South Poles, with positive values increasing northward.In WGS 84, this is center of mass of the Earth. The origin at the center of the chosen ellipsoid.The ECEF coordinate system has the following parameters: The ECEF coordinates (x, y, z) shown in relation to latitude and longitude The geocentric altitude is a type of altitude defined as the difference between the two aforementioned quantities: h ' = R- R 0 it is not to be confused for the geodetic altitude.Ĭonversions between ECEF and geodetic coordinates (latitude and longitude) are discussed at geographic coordinate conversion. The distance from a given point of interest to the center of Earth is called the geocentric distance, R = ( X 2 + Y 2 + Z 2) 0.5, which is a generalization of the geocentric radius, R 0, not restricted to points on the reference ellipsoid surface. Its most common use is in tracking the orbits of satellites and in satellite navigation systems for measuring locations on the surface of the Earth, but it is also used in applications such as tracking crustal motion. The Earth-centered, Earth-fixed coordinate system (acronym ECEF), also known as the Geocentric coordinate system, is a cartesian spatial reference system that represents locations in the vicinity of the Earth (including its surface, interior, atmosphere, and surrounding outer space) as X, Y, and Z measurements from its center of mass.