GMT (Generic Mapping Tools)

The GMT data processing and display software package is a collection of public-domain Unix tools that allows you to manipulate x,y and x,y,z data sets (filtering, trend fitting, gridding, projecting, etc.) and produce PostScript illustrations ranging from simple x-y plots, via contour maps, to artificially illuminated surfaces and 3-d perspective views in black/white or 24bit color.

Linear, log10, and power scaling is supported in additon to 20 common map projections. The processing and display routines within GMT are completely general and will handle any (x,y) or (x,y,z) data as input. The package also includes a database of coastlines, lakes and rivers, and political boundaries. Another useful feature is a Fortran or C-callable PostScript plotting library that can be used to access many of the output capabilities of GMT from within your own programs.

A typical GMT session will involve a series of commands, put together in a UNIX shell script. Each tool has a large number of command line options, which determine such things as what map projection is being used, the area of interest and the weight and colour of the pen used for drawing lines and annotation.

Using GMT on the IT AIX system

To get started with GMT on the IT AIX system, type:

  . use gmt
  man gmt

Full GMT documentation is available locally at


Some locally-developed examples are shown below. Other examples are available at the GMT home page at .

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