7.12 Optimal triangulation of data

Our next example (Figure 7.12)
operates on a data set of topographic
readings non-uniformly distributed in the plane (Table
5.11 in Davis: *Statistics and Data Analysis in Geology*,
J. Wiley). We use * triangulate* to perform the optimal
Delaunay triangulation, then use the output to draw the
resulting network. We label the node numbers as well as
the node values, and call

#!/bin/csh # GMT EXAMPLE 12 # # $Id: job12.csh,v 1.7 2004/07/14 00:46:17 pwessel Exp $ # # Purpose: Illustrates Delaunay triangulation of points, and contouring # GMT progs: makecpt, minmax, pscontour, pstext, psxy, triangulate # Unix progs: $AWK, echo, rm # # First draw network and label the nodes triangulate table_5.11 -M >! net.xy psxy -R0/6.5/-0.2/6.5 -JX3.06i/3.15i -B2f1WSNe -M net.xy -W0.5p -P -K -Y4.65i >! example_12.ps psxy table_5.11 -R -J -O -K -Sc0.12i -Gwhite -W0.25p >> example_12.ps $AWK '{print $1, $2, 6, 0, 0, "CM", NR-1}' table_5.11 | \ pstext -R -J -O -K >> example_12.ps # Then draw network and print the node values psxy -R -J -B2f1eSNw -M net.xy -W0.5p -O -K -X3.25i >> example_12.ps psxy -R -J -O -K table_5.11 -Sc0.03i -Gblack >> example_12.ps $AWK '{printf "%g %s 6 0 0 LM %g\n", $1, $2, $3}' table_5.11 | pstext -R -J -O -K -W255o \ -C0.01i/0.01i -D0.08i/0i -N >> example_12.ps # Then contour the data and draw triangles using dashed pen # Use "minmax" and "makecpt" to make a color palette (.cpt) file set z = `minmax table_5.11 -C -I25` makecpt -Cjet -T$z[5]/$z[6]/25 >! topo.cpt pscontour -R -J table_5.11 -B2f1WSne -W0.75p -Ctopo.cpt -L0.25pta -G1i/0 -X-3.25i -Y-3.65i -O -K \ -U"Example 12 in Cookbook" >> example_12.ps # Finally color the topography pscontour -R -J table_5.11 -B2f1eSnw -Ctopo.cpt -I -X3.25i -O -K >> example_12.ps echo "3.16 8 30 0 1 BC Delaunay Triangulation" | pstext -R0/8/0/11 -Jx1i -O -X-3.25i >> example_12.ps # \rm -f net.xy topo.cpt .gmt*