Welcome to Proj4J

Proj4J is a Java library to transform point coordinates from one geographic coordinate system to another, including datum transformations.

The core of this library is a port of the PROJ.4 C library. The projection algorithms, concepts and coordinate system definitions are all taken directly from PROJ.4. These are wrapped in a Java class model which follows standard Java conventions and OO best practices.

Proj4J is a part of the MetaCRS group of projects, hosted by OSGeo.

Documentation

• The PROJ.4 documentation is the best reference for details of the coordinate system specification language, projection algorithms and supported parameters.
• the Version History lists the evolution of features of the library
• the Javadoc describes the API

Mailing List

A mailing list is available for users and developers of Proj4J.

• Subscription, unsubscription and a web archive are at http://lists.osgeo.org/mailman/listinfo/proj4j.
• Direct link to the mailing list archive.

Development

• SVN repository: http://svn.osgeo.org/metacrs/proj4j.
• Browse source here.

Bug Tracking

• Submit a new bug report (you need to login with an OSGeo Userid)
• List Open Bugs
• List Open Enhancement Requests

License

Related Resources

• The PROJ.4 site has a comprehensive list of resources dealing with Coordinate Systems in general and the PROJ.4 library in particular.

History

The Proj4J codebase is based on a partial port of PROJ.4 carried out by JHLabs circa 2006. The JHLabs port provided a large number of the PROJ.4 projections, but did not support some PROJ.4 features such as datum transformation.