man GMT () - The Generic Mapping Tools data processing and display software package


gmt - The Generic Mapping Tools data processing and display software package


GMT 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 25 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.


GMT is also a wrapper script that can start any of the programs:

GMT module module-options

where module is the name of a GMT program and the options are those that pertain to that particular program.


The following is a summary of all the programs supplied with GMT and a very short description of their purpose. Detailed information about each program can be found in the separate manual pages.

blockmean L2 (x,y,z) data filter/decimator

blockmedian L1 (x,y,z) data filter/decimator

blockmode Mode (x,y,z) data filter/decimator

filter1d Filter 1-D data sets (time series)

fitcircle Finds the best-fitting great circle to a set of points

gmtconvert Convert between ASCII and binary 1-D tables

gmtdefaults List the current default settings

gmtmath Mathematical operations on data tables

gmtset Set individual default parameters

gmtselect Extract data subsets based on spatial criteria

grdfilter Filter 2-D data sets in the space domain

grd2cpt Make a color palette table from a grdfile

grd2xyz Conversion from 2-D gridded file to table data

grdclip Limit the z-range in gridded data

grdcontour Contouring of 2-D gridded data

grdcut Cut a sub-region from a grd file

grdedit Modify header information in a 2-D gridded file

grdfft Operate on grdfiles in the frequency domain

grdgradient Compute directional gradient from grdfiles

grdhisteq Histogram equalization for grdfiles

grdimage Produce images from 2-D gridded data

grdinfo Get information about grd files

grdlandmask Create mask grdfile from shoreline data base

grdmask Reset nodes outside a clip path to a constant

grdmath Mathematical operations on grdfiles

grdpaste Paste together grdfiles along a common edge

grdproject Project gridded data onto a new coordinate system

grdreformat Converting between different grdfile formats

grdsample Resample a 2-D gridded data set onto a new grid

grdtrend Fits polynomial trends to grdfiles

grdtrack Sampling of 2-D data set along 1-D track

grdvector Plot vector fields from grdfiles

grdview 3-D perspective imaging of 2-D gridded data

grdvolume Volume calculations from 2-D gridded data

makecpt Make GMT color palette tables

mapproject Forward or inverse map projections of table data

minmax Find extreme values in data tables

nearneighbor Nearest-neighbor gridding scheme

project Project data onto lines/great circles

psbasemap Create a basemap plot

psclip Use polygon files to define clipping paths

pscoast Plot coastlines and filled continents on maps

pscontour Contour xyz-data by triangulation

pshistogram Plot a histogram

psimage Plot images (Sun rasterfiles) on maps

psmask Create overlay to mask out regions on maps

psrose Plot sector or rose diagrams

psscale Plot grayscale or colorscale on maps

pstext Plot textstrings on maps

pswiggle Draw time-series along track on maps

psxy Plot symbols, polygons, and lines on maps

psxyz Plot symbols, polygons, and lines in 3-D

sample1d Resampling of 1-D table data sets

spectrum1d Compute various spectral estimates from time-series

splitxyz Split xyz-files into several segments

surface A continuous curvature gridding algorithm

trend1d Fits polynomial or Fourier trends to y = f(x) data

trend2d Fits polynomial trends to z = f(x,y) data

triangulate Perform optimal Delaunay triangulation and gridding

xyz2grd Convert equidistant xyz data to a 2-D grd file


Look up the individual man pages for details. These pages are in /usr/share/man/man1/*.1gmt.gz on a Debian system. Information is also available on the GMT home page or locally under /usr/share/doc/gmt-doc/gmt_services.html if the gmt-doc package is installed.


Wessel, P., and W. H. F. Smith, 2001, The Generic Mapping Tools (GMT) version 3.4 Technical Reference & Cookbook, SOEST/NOAA.

Wessel, P., and W. H. F. Smith, 1998, New, Improved Version of Generic Mapping Tools Released, EOS Trans., AGU, 79 (47), p. 579.

Wessel, P., and W. H. F. Smith, 1995, New Version of the Generic Mapping Tools Released, EOS Trans., AGU, 76 (33), p. 329.

Wessel, P., and W. H. F. Smith, 1995, New Version of the Generic Mapping Tools Released, http: American Geophysical Union.

Wessel, P., and W. H. F. Smith, 1991, Free Software Helps Map and Display Data, EOS Trans., AGU, 72 (41), p. 441.