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The World Geodetic System (WGS) is a standard used in cartography, geodesy, and satellite navigation including GPS.The current version, WGS 84, defines an Earth-centered, Earth-fixed coordinate system and a geodetic datum, and also describes the associated Earth Gravitational Model (EGM) and World Magnetic Model (WMM).
The standard style for OpenStreetMap, like most Web maps, uses the Web Mercator projection. Web Mercator, Google Web Mercator, Spherical Mercator, WGS 84 Web Mercator [1] or WGS 84/Pseudo-Mercator is a variant of the Mercator map projection and is the de facto standard for Web mapping applications.
A geodetic datum or geodetic system (also: geodetic reference datum, geodetic reference system, or geodetic reference frame, or terrestrial reference frame) is a global datum reference or reference frame for unambiguously representing the position of locations on Earth by means of either geodetic coordinates (and related vertical coordinates) or geocentric coordinates. [1]
Below is an example of a datum shift operation in WKT 2 format. Contrarily to an equivalent description in WKT 1 format, the WKT 2 description specifies the source and target coordinate reference systems, together with the domain of validity and the accuracy (in metres) that we can expect from this operation:
Grid-based transformations directly convert map coordinates from one (map-projection, geodetic datum) pair to map coordinates of another (map-projection, geodetic datum) pair. An example is the NADCON method for transforming from the North American Datum (NAD) 1927 to the NAD 1983 datum. [ 26 ]
The first EGM, EGM84, was defined as a part of WGS84 along with its reference ellipsoid. WGS84 combines the old GRS 80 with the then-latest data, namely available Doppler, satellite laser ranging, and Very Long Baseline Interferometry ( VLBI ) observations, and a new least squares method called collocation. [ 3 ]
It uses the WGS 1984 Datum and is based on lines of longitude (LONG) and latitude (LAT). It is intended to provide an integrated common frame of reference for joint force situational awareness to facilitate air-to-ground coordination, deconfliction, integration, and synchronization.
European Datum 1950: SAD69: South American Datum 1969: GRS 80: Geodetic Reference System 1980: ISO 6709: Geographic point coord. 1983: NAD 83: North American Datum 1983: WGS 84: World Geodetic System 1984: NAVD 88: N. American Vertical Datum 1988: ETRS89: European Terrestrial Ref. Sys. 1989: GCJ-02: Chinese obfuscated datum 2002: Geo URI ...