PROJ is an open-source software library used for performing cartographic projections and coordinate transformations. It is widely used in geographic information systems (GIS), remote sensing, and mapping applications. PROJ provides a powerful framework for converting geographic coordinates (latitude and longitude) to projected coordinates (e.g., UTM, state plane) and vice versa. Originally developed in the 1970s, PROJ has evolved over the years and is now maintained by a community of developers.
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