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<H2><A NAME="SECTION003234000000000000000">
O.3.4 Label placement at simple line intersections</A>
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Often, it will suffice to place contours at the imaginary intersections between the
contour lines and a well-placed straight line segment. The <B>-Gl</B> or <B>-GL</B>
algorithms work well in those cases:
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<PRE>pscoast -R50/160/-15/15 -JM5.3i -Glightgray -A500 -K -P > GMT_App_O_4.ps
grdcontour geoid.grd -J -O -B20f10WSne -C10 -A20+d+s8 -GLZ-/Z+ -S10 -T:LH >> GMT_App_O_4.ps
</PRE>
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The obvious choice in this example is to specify a great circle between the high and
the low, thus placing all labels between these extrema.
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<DIV ALIGN="CENTER"><A NAME="fig:GMT_App_O_4"></A><A NAME="32942"></A>
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<CAPTION ALIGN="BOTTOM"><STRONG>Figure O.4:</STRONG>
Labels are placed at the intersections between contours and the
great circle specified in the <B>-GL</B> option.</CAPTION>
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The thin debug line in Figure <A HREF="#fig:GMT_App_O_4">O.4</A> shows the great circle and the
intersections where labels are plotted. Note that any number of such lines could be specified;
here we are content with just one.
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<ADDRESS>
Paul Wessel
2010-01-14
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