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The coordinate origin of WGS 84 is meant to be located at the Earth's center of mass; the uncertainty is believed to be less than 2 cm. [7] Handheld GPS receiver at the Royal Observatory, Greenwich, indicating that the Greenwich meridian is 0.089 arcminutes (or 5.34 arcseconds) west of the WGS 84 datum (the IERS Reference Meridian)
A coordinate system conversion is a conversion from one coordinate system to another, with both coordinate systems based on the same geodetic datum. Common conversion tasks include conversion between geodetic and earth-centered, earth-fixed coordinates and conversion from one type of map projection to another.
Another update brought it to WGS 84 (G1674). The WGS 84 datum, within two meters of the NAD 83 datum used in North America, is the only world referencing system in place today. WGS 84 is the default standard datum for coordinates stored in recreational and commercial GPS units.
The ECEF that is used for the Global Positioning System (GPS) is the geocentric WGS 84, which currently includes its own ellipsoid definition. [5] Other local datums such as NAD 83 may also be used. Due to differences between datums, the ECEF coordinates for a location will be different for different datums, although the differences between ...
A geographic coordinate system (GCS) is a spherical or geodetic coordinate system for measuring and communicating positions directly on Earth as latitude and longitude. [1] It is the simplest, oldest and most widely used type of the various spatial reference systems that are in use, and forms the basis for most others.
Geodetic latitude and geocentric latitude have different definitions. Geodetic latitude is defined as the angle between the equatorial plane and the surface normal at a point on the ellipsoid, whereas geocentric latitude is defined as the angle between the equatorial plane and a radial line connecting the centre of the ellipsoid to a point on the surface (see figure).
GPS just uses WGS 84, ITRF2020 since January 2024 (but used many versions of WGS 84 before), a little modified with International GNSS Service (IGS) implementation, IGS20. BeiDou Coordinate System, China Terrestrial Reference Frame (CTRF) 2000 = ITRF97 at epoch 2000.0; own implementation.
The practical impact is that if you use a modern GPS device set to work in NAD 83 or WGS 84 to navigate to NAD 27 coordinates (as from a topo map) near Seattle, you would be off by about 95 meters (not far enough west), and you'd be about 47 meters off near Miami (not far enough north-northeast), whereas you would be much closer for points near ...