Next: 6.20 Custom map symbols Up: 6. Cook-book Previous: 6.18 Volumes and Spatial Contents Index

#
6.19 Color patterns on maps

GMT 3.1 introduced color patterns and this examples give a few cases of how to use this new feature. We make a phony poster that advertises an international conference on GMT in Honolulu. We use grdmath, makecpt, and grdimage to draw pleasing color backgrounds on maps, and overlay pscoast clippaths to have the patterns change at the coastlines. The middle panel demonstrates a simple pscoast call where the built-in pattern # 86 is drawn at 100 dpi but with the black and white pixels replaced with color combinations. The final panel repeats the top panel except that the land and sea images have changed places (Figure 6.19).

    gmtset COLOR_MODEL rgb
    grdmath -R-180/180/-90/90 -I1 -F Y COSD 2 POW = lat.grd
    grdmath -R-180/180/-90/90 -I1 -F X = lon.grd
    echo "0 255 255 255 1 0 0 255" >! lat.cpt
    makecpt -Crainbow -T-180/180/60 -Z >! lon.cpt
    grdimage lat.grd -JI0/6.5i -Clat.cpt -P -K -Y7.5i -B0 >! example_19.ps
    pscoast -R -JI -O -K -Dc -A5000 -Gc >> example_19.ps
    grdimage lon.grd -JI -Clon.cpt -O -K >> example_19.ps
    pscoast -R -JI -O -K -Q >> example_19.ps
    pscoast -R -JI -O -K -Dc -A5000 -W0.25p >> example_19.ps
    echo "0 20 32 0 1 CM FIRST INTERNATIONAL" | pstext -R -JI -O -K -G255/0/0 -S0.5p >> example_19.ps
    echo "0 -10 32 0 1 CM GMT CONFERENCE" | pstext -R -JI -O -K -G255/0/0 -S0.5p >> example_19.ps
    echo "0 -30 18 0 1 CM Honolulu, Hawaii, April 1, 2000" | pstext -R -JI -O -K -G0/255/50 -S0.25p \
       >> example_19.ps
    pscoast -R -JI -O -K -Dc -A5000 -Gp100/86:F255/0/0B255/255/0 -Sp100/7:F255/0/0B0/0/0 -B0 -Y-3.25i \
       >> example_19.ps
    echo "0 15 32 0 1 CM SILLY USES OF" | pstext -R -JI -O -K -G50/255/50 -S0.5p >> example_19.ps
    echo "0 -15 32 0 1 CM GMT COLOR PATTERNS" | pstext -R -JI -O -K -G255/0/255 -S0.5p >> example_19.ps
    grdimage lon.grd -JI -Clon.cpt -O -K -Y-3.25i -B0 -U"Example 19 in Cookbook" >> example_19.ps
    pscoast -R -JI -O -K -Dc -A5000 -Gc >> example_19.ps
    grdimage lat.grd -JI -Clat.cpt -O -K >> example_19.ps
    pscoast -R -JI -O -K -Q >> example_19.ps
    pscoast -R -JI -O -K -Dc -A5000 -W0.25p >> example_19.ps
    echo "0 20 32 0 1 CM FIRST INTERNATIONAL" | pstext -R -JI -O -K -G255/0/0 -S0.5p >> example_19.ps
    echo "0 -10 32 0 1 CM GMT CONFERENCE" | pstext -R -JI -O -K -G255/0/0 -S0.5p >> example_19.ps
    echo "0 -30 18 0 1 CM Honolulu, Hawaii, April 1, 2000" | pstext -R -JI -O -G0/255/50 -S0.25p \
       >> example_19.ps
    \rm -f l*.grd l*.cpt .gmt*

Figure 6.19: Using color patterns in illustrations.

Next: 6.20 Custom map symbols Up: 6. Cook-book Previous: 6.18 Volumes and Spatial Contents Index