O.3.5 Label placement at general line intersections

If (1) the number of intersecting straight line segments needed to pick the desired label positions becomes too large to be given conveniently on the command line, or (2) we have another data set or lines whose intersections we wish to use, the general crossing algorithm makes more sense:

pscoast -R50/160/-15/15 -JM5.5i -Glightgray -A500 -K -P > GMT_App_O_5.ps
grdcontour geoid.grd -JM -O -B20f10WSne -C10 -A20+d+s8 -GXcross.d -S10 -T:LH >> GMT_App_O_5.ps

Figure O.5: Labels are placed at the intersections between contours and the multi-segment lines specified in the -GX option.

In this case, we have created three strands of lines whose intersections with the contours define the label placements, presented in Figure O.5.