#!/bin/bash
#		GMT EXAMPLE 29
#		$Id$
#
# Purpose:	Illustrates spherical surface gridding with Green's function of splines
# GMT modules:	makecpt, grdcontour, grdimage, grdmath greenspline, psscale, pstext
# Unix progs:	rm, echo
#
ps=example_29.ps

# This example uses 370 radio occultation data for Mars to grid the topography.
# Data and information from Smith, D. E., and M. T. Zuber (1996), The shape of
# Mars and the topographic signature of the hemispheric dichotomy, Science, 271, 184-187.

# Make Mars PROJ_ELLIPSOID given their three best-fitting axes:
a=3399.472
b=3394.329
c=3376.502
gmt grdmath -Rg -I4 -r X COSD $a DIV DUP MUL X SIND $b DIV DUP MUL ADD Y COSD DUP MUL MUL Y \
	SIND $c DIV DUP MUL ADD SQRT INV = PROJ_ELLIPSOID.nc

#  Do both Parker and Wessel/Becker solutions (tension = 0.9975)
gmt greenspline -RPROJ_ELLIPSOID.nc mars370.txt -D4 -Sp -Gmars.nc
gmt greenspline -RPROJ_ELLIPSOID.nc mars370.txt -D4 -Sq0.9975 -Gmars2.nc
# Scale to km and remove PROJ_ELLIPSOID
gmt grdmath mars.nc 1000 DIV PROJ_ELLIPSOID.nc SUB = mars.nc
gmt grdmath mars2.nc 1000 DIV PROJ_ELLIPSOID.nc SUB = mars2.nc
gmt makecpt -Crainbow -T-7/15 > mars.cpt
gmt grdimage mars2.nc -I+ne0.75+a45 -Cmars.cpt -B30g30 -BWsne -JH0/7i -P -K -E200 \
	--FONT_ANNOT_PRIMARY=12p -X0.75i > $ps
gmt grdcontour mars2.nc -J -O -K -C1 -A5 -Glz+/z- >> $ps
gmt psxy -Rg -J -O -K -Sc0.045i -Gblack mars370.txt  >> $ps
echo "0 90 b)" | gmt pstext -R -J -O -K -N -D-3.5i/-0.2i -F+f14p,Helvetica-Bold+jLB >> $ps
gmt grdimage mars.nc -I+ne0.75+a45 -Cmars.cpt -B30g30 -BWsne -J -O -K -Y4.2i -E200 \
	--FONT_ANNOT_PRIMARY=12p >> $ps
gmt grdcontour mars.nc -J -O -K -C1 -A5 -Glz+/z- >> $ps
gmt psxy -Rg -J -O -K -Sc0.045i -Gblack mars370.txt  >> $ps
gmt psscale -Cmars.cpt -O -K -R -J -DJBC+o0/0.15i+w6i/0.1i -I --FONT_ANNOT_PRIMARY=12p -Bx2f1 -By+lkm >> $ps
echo "0 90 a)" | gmt pstext -R -J -O -N -D-3.5i/-0.2i -F+f14p,Helvetica-Bold+jLB >> $ps
# Clean up
rm -f *.nc mars.cpt
