WGS 84
Introduction
The World Geodetic System 1984 (WGS 84) is a global datum and reference coordinate system used for geodesy, navigation, and mapping. Developed by the United States Department of Defense (DoD), it is the standard used in Global Positioning System (GPS) technology and is widely adopted in cartography, geodesy, and navigation worldwide.
Development and Implementation
The development of WGS 84 was initiated by the DoD to establish a consistent, accurate, and globally applicable geodetic system. It was designed to replace the earlier WGS 72, which had limitations in terms of global accuracy and consistency. The system was officially implemented in 1987 and has been updated several times since its inception to improve its accuracy and applicability.
Geodetic Datum
A datum is a reference from which measurements are made. In geodesy, it is a set of reference points on the Earth's surface against which position measurements are made, and an associated model of the shape of the Earth (ellipsoid) to define a geographic coordinate system. The WGS 84 datum, which is an Earth-centered, Earth-fixed terrestrial reference system and geodetic datum, is based on an ellipsoidal model of the Earth.
Coordinate System
The WGS 84 system uses a Cartesian coordinate system, a type of coordinate system that specifies each point uniquely in a plane by a pair of numerical coordinates, which are the signed distances to the point from two fixed perpendicular directed lines, measured in the same unit of length. The coordinates are often chosen such that one of the numbers represents a vertical position and two or three of the numbers represent a horizontal position.
Applications
WGS 84 is extensively used in a variety of applications. It is the default datum used for the Global Positioning System (GPS) network, and by the International Civil Aviation Organization (ICAO) for aircraft navigation. It is also used in Geographic Information Systems (GIS) and remote sensing. In addition, it is used for mapping and surveying by many national and international organizations.
Updates and Revisions
Since its implementation, WGS 84 has undergone several updates and revisions to improve its accuracy. These updates have been driven by advances in technology, such as the advent of GPS, and improvements in the measurement and understanding of the Earth's shape and gravitational field.