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<HTML>
<HEAD>
<TITLE>grdreformat</TITLE>
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<BODY>
<H1>grdreformat</H1>
<HR>
<PRE>
<!-- Manpage converted by man2html 3.0.1 -->
grdreformat - Converting between different grdfile for
mats.
</PRE>
<H2>SYNOPSIS</H2><PRE>
<B>grdreformat</B> <I>ingrdfile</I>[<I>=id</I>[<I>/scale/offset</I>[<I>/nanvalue</I>]]] <I>out</I>
<I>grdfile</I>[<I>=id</I>[<I>/scale/offset</I>[<I>/nanvalue</I>]]] [
<B>-R</B><I>west/east/south/north</I>[<B>r</B>] ] [ <B>-V</B> ]
</PRE>
<H2>DESCRIPTION</H2><PRE>
<B>grdreformat</B> reads a grdfile in one format and writes it
out using another format. As an option the user may select
a subset of the data to be written and to specify scaling,
translation, and nan-value.
<I>ingrdfile</I>
The grdfile to be read. Append format =<I>id</I> number if
not a standard GMT netcdf-based grdfile. If <I>id</I> is
set, you may optionally append <I>scale</I> and <I>offset</I> to
scale the data and then add an offset. If <I>scale</I> and
<I>offset</I> are supplied you may also append a value
that represent 'not-a-number' (for floating-point
grids this is unneccesary since the IEEE NaN is
used; however short integers need a value which
means no data available.)
<I>outgrdfile</I>
The grdfile to be written. Append format =<I>id</I> number
if not a standard GMT netcdf-based grdfile. If <I>id</I>
is set, you may optionally append <I>scale</I> and <I>offset</I>
to scale the data and then add an offset. If <I>scale</I>
and <I>offset</I> are supplied you may also append a value
that represent 'not-a-number' (for floating-point
grids this is unneccesary since the IEEE NaN is
used; however short integers need a value which
means no data available.) For format =<I>id</I> > 0 the
size of the GMT grdheader block is <I>hsize</I> = 896
bytes, and the total size of the file is <I>hsize</I> <I>+</I> <I>nx</I>
<I>*</I> <I>ny</I> <I>*</I> <I>item</I><B>_</B><I>size</I>, where item_size <I>is</I> <I>the</I> <I>size</I> <I>in</I>
<I>bytes</I> <I>of</I> <I>each</I> <I>element</I> <I>(1,</I> <I>2,</I> <I>4).</I> <I>Bit</I> <I>grids</I> <I>are</I>
<I>stored</I> <I>using</I> <I>4-byte</I> <I>integers,</I> <I>each</I> <I>holding</I> <I>32</I> <I>bits,</I>
<I>so</I> <I>for</I> <I>these</I> <I>files</I> <I>the</I> <I>size</I> <I>equation</I> <I>is</I> <I>modified</I> <I>by</I>
<I>using</I> <I>ceil</I> <I>(nx</I> <I>/</I> <I>32)</I> <I>*</I> <I>4</I> <I>instead</I> <I>of</I> <I>nx.</I> <I>For</I> <I>header</I>
<I>and</I> <I>grid</I> <I>details,</I> <I>see</I> <I>Appendix</I> <I>B.</I>
</PRE>
<H2>OPTIONS</H2><PRE>
<B>-R</B> <I>west,</I> <I>east,</I> <I>south,</I> and <I>north</I> specify the Region of
interest. To specify boundaries in degrees and min
utes [and seconds], use the dd:mm[:ss] format.
Append <B>r</B> if lower left and upper right map coordi
nates are given instead of wesn.
<B>-V</B> Selects verbose mode, which will send progress
To create a 4-byte raw floating point grid from the netcdf
file data.grd, try
grdreformat data.grd ras_data.b4=1 <B>-V</B>
To make a 2-byte short integer file, scale it by 10, sub
tract 32000, setting NaNs to -9999, do
grdreformat values.grd shorts.i2=2/10/-32000/-9999 <B>-V</B>
To create a Sun standard 8-bit rasterfile for a subset of
the data file image.grd, assuming the range in image.grd
is 0-1 and we need 0-255, try
grdreformat image.grd <B>-R</B>-60/-40/-40/-30 image.ras8=3/255/0
<B>-V</B>
</PRE>
<H2>SEE ALSO</H2><PRE>
<I>gmt</I>(l), <I><A HREF="grdmath.html">grdmath</A></I>(l)
</PRE>
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