Generic Mapping Tools (GMT) is an open source collection of ~60 tools for
manipulating geographic and Cartesian data sets (including filtering,
trend fitting, gridding, projecting, etc.) and producing Encapsulated
PostScript File (EPS) illustrations ranging from simple x-y plots via
contour maps to artificially illuminated surfaces and 3-D perspective
views. GMT supports ~30 map projections and transformations and comes
with support data such as GSHHS coastlines, rivers, and political
boundaries. GMT is developed and maintained by Paul Wessel and Walter
H. F. Smith with help from a global set of volunteers, and is supported
by the National Science Foundation. It is released under the GNU General
Public License.

Please note, Shewchuk's triangulation routine used in some parts of GMT is 
not distributed under the GNU Public Licence. If you work for a for-profit 
organisation, you should read Shewchuk's copyright statement first (you
can find it at http://gmt.soest.hawaii.edu/gmt/README.TRIANGLE).
This script enables the (much faster) Shewchuk triangulation routine by
by default; should you need to change this behaviour, set SHEWCHUK to "no"
in the build script.

gdal is an optional dependency.