Generic Mapping Tools (GMT)

Maps

#!/bin/bash

psbasemap -R0/100/0/10 -JX5i/3i -Ba20g10/a2f1g2WSne \ -X2 -Y14 -K -P > plot.ps

sample1d -I1 << END |\nawk '{print $1, sqrt($1)}' > input.dat0100END

psxy input.dat -R -JX -W5t15_15:0 -K -O >> plot.ps

sample1d input.dat -I10 |\psxy -R -JX -St0.5 -G255/0/0 -W5/0/255/0 -O >> plot.ps

gs plot.ps

Final script for Example 1

Correction on the –W flagpsxy input.dat –R –JX -W5t15_15:0 -K –O >> plot.ps

The –W command can be quite complicated and is specified in order –W[width],[color],[texture]

In this example, the first 5 represents line width, the t signifies a texture follows, the 15_15 specifies the dash and space width, and the :0 specifies that a dash is used.

Alternately, -W5,0,15_15:- does the same thing.

Common command options on first, and possibly subsequent, calls

• Need on all calls-R Define region for plot – will need on first call and at least “–R” on subsequent-J Define projection for plot – will need this on all calls if need to define region

Common command options on first, and possibly subsequent, calls

• (Generally) Need on first call only-B Borders -- annotation, frame, grid. Only need on first (or a single) call.-P Switch between landscape and portrait modes-X Shift X axis-Y Shift Y axis

Common command options on first, and possibly subsequent, calls.

• Need when needed.-K Don’t close PostScript (showpage), use when more will follow

• need on all but last GMT call

-O Don’t initialize PostScript, use when appending to pre-existing file

• need on all but first GMT call• use both –K and –O when putting a large

number of GMT call outputs together

Common command options on first, and possibly subsequent, calls.

• Need when needed.-V Verbose (prints out stuff to standard error for user).-H Header records (tells GMT to skip first H lines of ascii input file)

GMT DefaultsThere are about 100 parameters which can be

adjusted individually to modify the appearance of plots or affect the manipulation of data. Each as a default value.

GMT defaults are kept in a file called ~/.gmtdefaults4. There are tons of them and you can find out what they are and what the mean reading the man page for gmtdefaults.

When a program is run, it initializes all parameters to the GMT defaults, then tries to open the file .gmtdefaults4 in the current directory. If not found, it will look for that file in a sub-directory ~/.gmt, and finally in your home directory itself. If successful, the program will read the contents and set the default values to those provided in the file.

To view your current gmtdefault settings%gmtdefaults –L

To view the list of options for each default parameter

%man gmtdefaults

Plotting Defaultsexample of start of .gmtdefaults4

# GMT-SYSTEM 4.2.1 Defaults file

#-------- Plot Media Parameters --

PAGE_COLOR = 255/255/255

PAGE_ORIENTATION = landscape

PAPER_MEDIA = letter

#--- Basemap Annotation Parameters --

ANNOT_MIN_ANGLE = 20

ANNOT_MIN_SPACING = 0

ANNOT_FONT_PRIMARY = Helvetica

ANNOT_FONT_SIZE = 14p

ANNOT_OFFSET_PRIMARY = 0.075i

Changing the defaultsYou can edit your local copy of .gmtdefaults4

using nedit or vim

You can explicitly reset a default within a script using the command gmtset

#!/bin/shgmtset PAPER_MEDIA letter MEASURE_UNIT cm

gmtset OUTPUT_DEGREE_FORMAT +D gmtset PLOT_DEGREE_FORMAT +D

How about making pretty MAPS?

Map projections available in GMT

List of “standard”

command line options.

The –J option sets the

“projection”

One has to look at the man page for each one as “different things

vary”

pscoast -R-90/-70/0/20 -JM6i -P -B5g5 -G180/120/60 > map1.ps

“All” gmt programs plot “maps” through the projection command line option or switch (even the x-y plot).

pscoast -R-90/-70/0/20 -JM6i -P -B5g5 -G180/120/60 > map1.ps

All projections give you two selections for specifying the scale

(note GMT takes the mapmakers attitude that a map has to have a predetermined/known scale – nicely filling the page does not cut it.)

pscoast -R-90/-70/0/20 -JM6i -P -B5g5 -G180/120/60 > map1.ps

-Jmparameters

(Mercator [C]). Specify one of: -Jmscale or -JMwidth Give scale along equator(1:xxxx or UNIT/degree).

pscoast -R-90/-70/0/20 -JM6i -P -B5g5 -G180/120/60 > map1.ps

-Jmlon0/lat0/scale or

-JMlon0/lat0/width

Give central meridian, standard latitude and scale along parallel(1:xxxx or UNIT/degree, UNIT = number inches or cms).

Mercator Projection:One way to address plotting sphere on a

plane (which is whole ‘nother subject)Conformal (maintains shapes)

Cylindrical projection

pscoast -R-130/-70/24/52 -JB-100/35/33/45/6i -B10g5:."Conic\ Projection": -N1/2p -N2/0.25p -A500 -G200 -W0.25p -P >! map.ps

Region is “rectangle”

on the spherical

earth.

-N for boundaries

(international, US/Canadian/Mexican state boundaries “built

in”), rivers.

pscoast -R-130/-70/24/52 -JB-100/35/33/45/6i -B10g5:."Conic\ Projection": -N1/2p -N2/0.25p -A500 -G200 -W0.25p -P >! map.ps

-A to get rid of small

water/island features

Albers projection

(b/B) – need to know

something (center and

standard parallels).

pscoast -R-130/-70/24/52 -JB-100/35/33/45/6i -B10g5:."Conic\ Projection”: -N1/2p -N2/0.25p -A500 -G200 -W0.25p -P >! map.ps

-Jblon0/lat0/lat1/lat2/scale or -JBlon0/lat0/lat1/lat2/width

Albers - Give projection center, two standard parallels, and scale (1:xxxx or

UNIT/degree).

AlbersAlso conformal (maintains/conserves

shape)Conical projection

pscoast -R0/360/-90/90 -JG280/30/6i -Bg30/g15 -Dc -A5000 \

-G255/255/255 -S150/50/150 -P >! map.ps

azimuthal Orthographic projection (g/G) mimics looking at earth from infinite distance.

pscoast -R0/360/-90/90 -JG280/30/6i -Bg30/g15 -Dc -A5000 \

-G255/255/255 -S150/50/150 -P >! map.ps

New option-DcControls resolution of coastline f fullh highl lowc crudeHelps manage file sizes.

Example 2

Simple location mapwith focalmechanisms

gmtset: To change individual GMT default parameters

pscoast: Plot coastlines, filled continents, rivers, and political borders

psxy: Plot symbols, polygons, and lines in 2-Dpstext: Plot text strings psmeca: Plot focal mechanisms on maps

#!/bin/sh

###Create a basemap for the Sumatra-Andaman Island region

#Set global variablesPlots=../BasicInfoCPT=/usr/local/GMT4.2.0/share/cpt

LATMIN=-6.2LATMAX=16LONMIN=90LONMAX=106

OUTFILE=$0.ps #What does the $0 signify on this line?

#Explicitly set some GMT default valuesgmtset MEASURE_UNIT cm ANOT_FONT_SIZE 12 LABEL_FONT_SIZE 12 gmtset BASEMAP_TYPE fancy

#Map# Create the basic basemap using GMT coastline datapscoast -JM15 -R$LONMIN/$LONMAX/$LATMIN/$LATMAX -Ba2f1WNes -Y5 -X3 -K -P \

-Dh -A100 -N1 -W1 -G155 > $OUTFILE

• -D Selects the resolution of the data set ((f)ull, (h)igh, (i)ntermediate, (l)ow, (c)rude)• -A Features with an area smaller than min_area in km^2 • -W and –G Control the fill color and line color of the land regions• -N Plots political boundaries. 1 is for national boundaries, 2 is for states in the Americas

#Plot basic tectonic information, including subduction zones and volcanoespsxy $Plots/trench.right.gmt -R -JM -M -W5/0 -Sf0.3i/0.08irt -G0 -O -K >> $OUTFILEpsxy $Plots/trench.left.gmt -R -JM -M -W5/0 -Sf0.3i/0.08ilt -G0 -O -K >> $OUTFILEpsxy $Plots/trench.other.gmt -R -JM -M -Wt30_30:1p5/0 -O -K >> $OUTFILEpsxy $Plots/transform.gmt -R -JM -M -Wt10_10:1p5/0 -O -K >> $OUTFILEpsxy $Plots/ridge.gmt -R -JM -M -W1/0 -O -K >> $OUTFILEpsxy $Plots/volcanoes.simkin+siebert.gmt -R -JM -St.35 -W1/0 -G0 -O -K >> $OUTFILE

• -M Multiple segment file. Segments are separated by a record whose first character is flag. [Default is '>']. Example of trench.right.gmt> 92.278 6.94891.903 7.663>

#Information for the 2004 Sumatra eventawk '{print $7, $6, $9/30}' $Plots/122604_032705.pde |\ #prints lat, lon,mag/30 psxy -R -JM -Sc -W1/0 -G255/255/100 -O -K >> $OUTFILE

• When no value is specified on the –S flag (ie 0.20), then the size of the circle (denoted by the c) is controlled by the third column of info sent to the psxy command.

So we are scaling the circle size by what earthquake parameter in this example?

• Example of 122604_032705.pde from http://neic.usgs.gov/neis/epic/epic_rect.html PDE-W 2004 12 26 005853.45 3.30 95.98 30 9.00 MwHRV 9C M STS...M PDE-W 2004 12 26 011710.33 4.94 94.27 30 5.50 mb GS .. . .......

psxy -R -JM -Sa.89 -W1/0 -G255/255/0 -: -O -K << END >> $OUTFILE3.3 95.98END

• -Sa creates a star• -: indicates that the data is in y-x format rather than x-y format. This is useful because we speak of earthquakes in terms of latitude (y) and longitude (x) and therefore tend to write geographic coordinates in this order as well.

#Global CMT solutions for events above Mw ~6.6psmeca -R -JM -Sm0.5 -G255/255/100 -T -O -K << END >> $OUTFILE#lon lat depth mrr mtt mpp mrt mrp mtp iexp name94.26 3.09 29 1.04 -0.43 -0.61 2.98 -2.40 0.43 29 X Y 122604A92.79 6.61 14 5.26 -0.84 -4.41 3.95 -2.91 2.10 26 X Y 122604B92.45 8.58 12 0.94 -0.12 -0.81 0.02 -0.27 0.32 26 X Y 122604C92.20 4.99 12 -0.02 -0.64 0.66 -0.11 -0.16 -0.80 26 X Y 010105A95.38 2.84 12 0.26 -0.17 -0.09 0.90 -0.91 0.16 26 X Y 022605AEND

• psmeca creates lower hemisphere projections, aka beachballs. It is a rather complicated little command.• -S Selects the meaning of the columns in the data file.• -Sa Focal mechanisms in Aki and Richard convention.• -Sc Focal mechanisms in Harvard CMT convention.• -Sm Seismic moment tensor (Harvard CMT, with zero trace).

• -Sd plot only the double couple part of moment tensor. • -Sz plot anisotropic part of moment tensor (zero trace). • http://www.globalcmt.org/CMTsearch.html

• -Sp Focal mechanisms given with partial data on both planes.• -Sx Principal axis.

• -G Controls fill of the compressive quadrant of the moment tensor• -T Plots the nodal planes

pstext -R -JM -: -O << END >> $OUTFILE-3.5 90.5 14 0 0 0 Yellow: 2004 Mw 9.2 series-5.75 90.5 14 0 0 0 CMT solutions for Mw >= 6.6END

• format is x, y, size, angle, font#, justify, text• %pstext –L will tell you the font # and font name• you can use [T|M|B][L|C|R] to specify justification

(top/middle/bottom/left/center/right)

gs $OUTFILE #gs indicates ghostscript

if you are using vim to edit this script

:!script.gmt will run the script, open the resulting file using gs, and you can see what you have done. If you don’t like it, type quit, and continue editing the file.

nawk commands as input to GMTnawk '{print $9, $8, $11}' EBH.HDF

You can put this into GMT several ways

If this is the only file you want to plot – this would work

nawk '{print $9, $8, $11}' EBH.HDF | pxsy …

If you had a number of files that needed conversion you could do it this way (only

need one psxy call)

psxy … << END ……`nawk '{print $9, $8, $11}' EBH.HDF`…END

Converting each file on the fly.

If you want to do the same thing to a list of files

filelist=“$SAMDATA/eq-rupt-1995.dat $DEM/eq-rupt-1960.dat”for FILE in $filelistdopsxy -R -$PROJ$SCALE -M$ -: $CONTINUE -W$LINETHICK/$PURPLE $FILE \$VBSE >> $OUTPUTFILEdone

Other ways to make list(notice the different kinds of quotes: “,’ and `)

filelist=`ls -1 $ROOT/dem/topocontours/andes_3000_*`

contourlist=‘1 2 3 4’

Some other nawk tricks – doing math and passing variables to nawk (quote heaven)

SCALE=`echo $STNDTMLON | \nawk ‘{print ($1>=0?$1:360+$1)”/”’${jTRESCALE}_1’*’$FACTOR’}’ `