Projects / Mapx


Mapx is a coordinate transformation library developed at National Snow and Ice Data Center (NSIDC). It was initially developed from equations given by Snyder (1982). Additional projections have been added as needed. The C version currently supports 11 common projections, in both spherical and ellipsoid forms when appropriate. The Java version lags behind somewhat and currently supports nine common projections, in both spherical and ellipsoid forms when appropriate.


Recent releases

  •  22 Mar 2012 14:52

    Release Notes: This release adds an "ungrid" commandline utility to extract points from a gridded binary file. The commandline utilities have been extended to allow saving the number of points contributing to each of the binned values ("irregrid") and to support C "float"-type formatted binary files ("regrid"). The forward and inverse functions now perform a self-test by calling each other once and comparing the results. The build system now generates position-independent (-fPIC) code by default. The .gpd and .mpp files have been updated. Minor fixes and clean-ups have been added.

    •  11 Jul 2006 08:12

      No changes have been submitted for this release.

      Recent comments

      22 Feb 2007 04:48 1gray

      One of the primary uses of Mapx for me was,

      until recent, the dependency of MODIS

      Swath-to-Grid Toolbox (MS2GT) on it. However,

      it appeared not too hard to replace `ll2cr' of

      MS2GT with the `proj' filter binary from a

      powerful PROJ.4 package. Indeed, you only have

      to transform input data from two separate

      `float' streams (latitude and longitude one) to

      a mixed `double' (longitude-latitude) one, and

      then vice versa for output. (You may need to

      negate the resulting Y-coordinates as well,

      since the Y-axis in carthography typically

      points up, while in computer graphics it oftenly

      points down.)

      14 Sep 2006 20:11 1gray

      Autoconfiscation of the package

      There's also a preliminary Autotools-based build system for the
      package at


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