GDAL is a library for reading and writing raster geospatial data
formats, and is released under an X/MIT style Open Source license by
the Open Source Geospatial Foundation. As a library, it presents a
single abstract data model to the calling application for all
supported formats. It may also be built with a variety of useful
command-line utilities for data translation and processing.

The related OGR library (which is part of the GDAL source tree)
provides a similar capability for simple features vector data.

This requires geos and proj.