Knowledge Base

What is the Map Transformations Library (Mapx)?

Mapx is a coordinate transformation library developed at NSIDC. The C code was initially developed from equations given by Snyder (1982) and tested against the examples in his Appendix A. Additional projections have been added as needed. The C version of Mapx currently supports 11 common projections, in both spherical and ellipsoid forms when appropriate.

The Java version was ported from the C version to simplify using the transforms in Java applets and applications. The Java lags behind the C somewhat and currently supports nine common projections, in both spherical and ellipsoid forms when appropriate.

The Mapx package is licensed under the GNU Lesser General Public License.


A poster describing some uses of the Mapx library.

Download the C library (mapx-x.x.tar.gz) or Java package (mapx-x.x.jar.gz; unsupported), and/or a collection of grid parameter definition files (nsidc_maps.tar.gz) to use with the software.

Documentation for the C library

  • A Mapping and Gridding Primer: Points, Pixels, Grids, and Cells. This is a tech memo written as part of the Mapx documentation that gives a brief introduction to mapping, gridding, and the associated terminology used in the Mapx library.
  • Usage messages are produced when you execute one of the utilities with no input parameters.

References

Snyder, J. P. 1982. Map Projections Used by the U.S. Geological Survey. U.S. Geological Survey Bulletin 1532.

Last Updated September 2019