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<H1><A NAME="SECTION002640000000000000000">
K.4 The Five Resolutions</A>
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<P>
We will demonstrate the power of the new database by starting with
a regional hemisphere map centered near Papua New Guinea and zoom
in on a specified point. The map regions will be specified in
projected km from the projection center, e.g., we may want the
map to go from -2000 km to +2000 km in the longitudinal direction
and -1500 km to +1500 km in the latitudinal direction.
However, <A NAME="tex2html722"
HREF="http://www.soest.hawaii.edu/gmt"><B>GMT</B></A> programs expects degrees in the <B>-R</B> option that
specifies the desired region. Given the chosen map projection we
can automate this process by using a simple cshell script that we
call <I>getbox</I><A NAME="15689"></A>:
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<PRE>
range=`(echo $2 $4; echo $3 $5) | mapproject $1 -R0/360/-90/90 -I -Fk -C`
echo $range | awk '{printf "-R%f/%f/%f/%fr\n",$1,$2,$3,$4}'
</PRE>
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Also, as we zoom in on the projection center we want to draw the
outline of the next map region on the plot. To do that we need
the geographical coordinates of the four corners of the region
rectangle. Again, we automate this task by adding the simple
script <I>getrect</I><A NAME="15793"></A>:
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(echo $2 $4; echo $3 $4; echo $3 $5; echo $2 $5) | mapproject $1 -R0/360/-90/90 -I -Fk -C
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<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A>
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<LI><A NAME="tex2html2965"
HREF="node137.html">K.4.1 The crude resolution (<B>-Dc</B>)</A>
<LI><A NAME="tex2html2966"
HREF="node138.html">K.4.2 The low resolution (<B>-Dl</B>)</A>
<LI><A NAME="tex2html2967"
HREF="node139.html">K.4.3 The intermediate resolution (<B>-Di</B>)</A>
<LI><A NAME="tex2html2968"
HREF="node140.html">K.4.4 The high resolution (<B>-Dh</B>)</A>
<LI><A NAME="tex2html2969"
HREF="node141.html">K.4.5 The full resolution (<B>-Df</B>)</A>
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<B> Previous:</B> <A NAME="tex2html2954"
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<ADDRESS>
Paul Wessel
2001-04-18
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