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<B> Next:</B> <A NAME="tex2html2665"
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<H2><A NAME="SECTION001722000000000000000"></A>
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B.2.2 Grid line and Pixel registration
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Scanline format means that the data are stored in rows (<I>y</I> = constant)
going from the ``top'' (<IMG
WIDTH="58" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
SRC="img136.gif"
ALT="$y = y_{max}$"> (north)) to the ``bottom''
(<IMG
WIDTH="56" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
SRC="img137.gif"
ALT="$y = y_{min}$"> (south)). Data within each row are ordered from
``left'' (<IMG
WIDTH="56" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
SRC="img138.gif"
ALT="$x = x_{min}$"> (west)) to ``right'' (<IMG
WIDTH="58" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
SRC="img139.gif"
ALT="$x = x_{max}$">
(east)). The <I>node_offset</I> signals how the nodes are laid out.
The grid is always defined as the intersections of all <I>x</I>
( <!-- MATH
$x = x_{min}, x_{min} + x_{inc}, x_{min} + 2 \cdot x_{inc}, \ldots, x_{max}$
-->
<IMG
WIDTH="273" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
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ALT="\( x = x_{min}, x_{min} + x_{inc}, x_{min} + 2 \cdot x_{inc}, \ldots, x_{max} \)"> )
and <I>y</I> ( <!-- MATH
$y = y_{min}, y_{min} + y_{inc}, y_{min} + 2 \cdot y_{inc}, \ldots, y_{max}$
-->
<IMG
WIDTH="273" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
SRC="img141.gif"
ALT="\( y = y_{min}, y_{min} + y_{inc}, y_{min} + 2 \cdot y_{inc}, \ldots, y_{max} \)"> )
lines. The two scenarios differ in which area each data point
represents.
The default registration in <A NAME="tex2html582"
HREF="http://www.soest.hawaii.edu/gmt"><B>GMT</B></A> is grid line registration. Most
programs can handle both types, and for some programs like <A NAME="tex2html583"
HREF="../grdimage.html"><I><B>grdimage</B></I></A><A NAME="13496"></A>
a pixel registered file makes more sense. Utility programs like
<A NAME="tex2html584"
HREF="../grdsample.html"><I><B>grdsample</B></I></A><A NAME="13505"></A> and <A NAME="tex2html585"
HREF="../grdproject.html"><I><B>grdproject</B></I></A><A NAME="13514"></A> will allow you to convert
from one format to the other.
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<!--Table of Child-Links-->
<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A>
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<LI><A NAME="tex2html2666"
HREF="node116.html">B.2.2.1 Grid line registration</A>
<LI><A NAME="tex2html2667"
HREF="node117.html">B.2.2.2 Pixel registration</A>
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<ADDRESS>
Paul Wessel
2001-04-18
</ADDRESS>
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