Spatial Reference System

A spatial reference system or coordinate reference system  is a coordinate-based system used to position objects, either on the earth’s surface in a 3D space, or on the earth’s reference surface in a 2D space, or on the other hand on the flat surface of the map in a 2D space. Many different sorts of spatial reference systems exist, the most widely used are the geographic coordinate systems and map coordinate systems.  A geographic coordinate system is a global system which consists of two angles, the latitude angle and the longitude angle. A map coordinate system is a 2D Cartesian coordinate system (x,y) that defines a specific map projection.