Referencing 3D
--------------

Experimental support for 3d referencing math transforms.

**License**

The gt-referencing-3d module is disributed under the LGPL license (as described in :doc:`welcome </welcome/license>`).
Some code and data in the gt-referencing-3d plugin are derived from NGA/NASA work available for unlimited
distribution.

References:

* http://earth-info.nima.mil/GandG/wgs84/gravitymod/.