PROJ is a library that provides methods to transform between different coordinate reference systems. A geographic coordinate reference system allows all points on the earth to be described as a set of coordinates (such as latitude, longitude and elevation). Different systems are used to represent the tridimensional earth on a flat, bidimensional map.
PROJ has been translated from C to other languages. These sub-projects include:
CS-Map (C++) - used in MapGuide.
EPSG.io - website to retrieve coordinate system definitions
SpatialReference.org - website to retrieve coordinate system definitions (obsolete).
Provides point transformation from one coordinate reference system to another.
Includes transformation between datums.
Large number of projection classes supported.
PROJ uses coordinate system definitions defined by the European Petroleum Survey Group (EPSG). Well Known Text (WKT) format.
Licence: X/MIT Open Source license
Software Version: 9.1.1
Supported Platforms: Windows, Linux, Mac
API Interfaces: C, C++, Python, Java, Ruby