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.

Features

• Uses the PROJ.4 coordinate system definition files
• Supports many PROJ.4 parameters
• Implements over 90 projections
• Provides coordinate system definitions for EPSG and ESRI authorities
• Simple, efficient API
• Provides a test framework compatible with the ​MetaCRS Test Suite
• Provides unit tests defined in MetaCRS format

Download

Status: Currently this library is still being created, and is not yet ready for download

• The current development source is available via anonymous SVN from ​http://svn.osgeo.org/metacrs/proj4j.

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

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

• Design Goals
• 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

Proj4J is licensed under the ​Apache License, Version 2.0.

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, via a simple API.

The Proj4J project was initiated with the following goals:

• move the JHLabs codebase into an open, supported environment
• improve the error handling and reporting
• improve the parsing and modeling of projection parameters
• improve the API to make it more flexible, expressive and descriptive
• add some missing projections
• support further PROJ.4 features such as datum transformation
• add a unit test framework (following the MetaCRS Unit Test design), with a comprehensive set of unit tests
• add further tools to support using the library (such as a GUI interface)