The invention of a

**geographic coordinate system**is generally credited to Eratosthenes of Cyrene, who composed his now-lost Geography at the Library of Alexandria in the 3rd century BC. A century later, Hipparchus of Nicaea improved on this**system**by determining latitude from stellar measurements rather than solar altitude and determining longitude by timings of lunar eclipses , rather than ...It supported a national

**coordinate****system**that spanned the continent, coded lines as arcs having a true embedded topology and it stored the attribute and locational information in separate files. As a result of this, Tomlinson has become known as the "father of GIS", particularly for his use of overlays in promoting the spatial analysis of convergent**geographic**data. [12]In geodesy, conversion among different

**geographic****coordinate**systems is made necessary by the different**geographic****coordinate**systems in use across the world and over time.**Coordinate**conversion is composed of a number of different types of conversion: format change of**geographic**coordinates, conversion of**coordinate**systems, or transformation to different geodetic datums .Another common

**coordinate system**for the plane is the polar**coordinate system**. A point is chosen as the pole and a ray from this point is taken as the polar axis . For a given angle θ , there is a single line through the pole whose angle with the polar axis is θ (measured counterclockwise from the axis to the line).Each reference

**coordinate**line is called a**coordinate**axis or just axis (plural axes) of the**system**, and the point where they meet is its origin, at ordered pair (0, 0). The coordinates can also be defined as the positions of the perpendicular projections of the point onto the two axes, expressed as signed distances from the origin.Each

**projected coordinate system**, such as "Universal Transverse Mercator WGS 84 Zone 26N," is defined by a choice of map projection (with specific parameters), a choice of geodetic datum to bind the**coordinate****system**to real locations on the earth, an origin point, and a choice of unit of measure.In mathematics, a

**spherical coordinate system**is a**coordinate****system**for three-dimensional space where the position of a point is specified by three numbers: the radial distance of that point from a fixed origin, its polar angle measured from a fixed zenith direction, and the azimuthal angle of its orthogonal projection on a reference plane that passes through the origin and is orthogonal to ...