GMT (1gmt)

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 gmt.soest.hawaii.edu 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.