INTRODUCTION

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.

SYNOPSIS

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.

GMT OVERVIEW

        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

RELATED TO GMT…

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.

REFERENCES

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.