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<title>SEGY2GRD</title>
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<h1 align="center">SEGY2GRD</h1>
<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#OPTIONS">OPTIONS</a><br>
<a href="#EXAMPLES">EXAMPLES</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<hr>
<h2>NAME
<a name="NAME"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">segy2grd
− Converting SEGY file to grid file format</p>
<h2>SYNOPSIS
<a name="SYNOPSIS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>segy2grd</b>
<i>segyfile</i> <b>−G</b><i>grdfile</i>
<b>−I</b><i>xinc</i>[<i>unit</i>][<b>=</b>|<b>+</b>][/<i>yinc</i>[<i>unit</i>][<b>=</b>|<b>+</b>]]
<b>−R</b><i>west</i>/<i>east</i>/<i>south</i>/<i>north</i>[<b>r</b>]
[ <b>−A</b>[<b>n</b>|<b>z</b>] ] [
<b>−D</b><i>xname</i>/<i>yname</i>/<i>zname</i>/<i>scale</i>/<i>offset</i>/<i>title</i>/<i>remark</i>
] [ <b>−F</b> ] [ <b>−N</b><i>nodata</i> ] [
<b>−S</b>[<i>zfile</i>] ] [ <b>−V</b> ] [
<b>−Z</b>[<i>flags</i>] ] [
<b>−:</b>[<b>i</b>|<b>o</b>] ] [
<b>−bi</b>[<b>s</b>|<b>S</b>|<b>d</b>|<b>D</b>[<i>ncol</i>]|<b>c</b>[<i>var1</i><b>/</b><i>...</i>]]
]</p>
<h2>DESCRIPTION
<a name="DESCRIPTION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>segy2grd</b>
reads an IEEE SEGY file and creates a binary grid file.
Either a simple mapping (equivalent to xyz2grd -Z) or a more
complicated averaging where a particular grid cell includes
values from more than one sample in the SEGY file can be
done. <b>segy2grd</b> will report if some of the nodes are
not filled in with data. Such unconstrained nodes are set to
a value specified by the user [Default is NaN]. Nodes with
more than one value will be set to the average value.
<i><br>
segyfile</i> is an IEEE floating point SEGY file. Traces are
all assumed to <br>
start at 0 time/depth.</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−G</b></p></td>
<td width="8%"></td>
<td width="78%">
<p><i>grdfile</i> is the name of the binary output grid
file.</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−I</b></p></td>
<td width="8%"></td>
<td width="78%">
<p><i>x_inc</i> [and optionally <i>y_inc</i>] is the grid
spacing. Append <b>m</b> to indicate minutes or <b>c</b> to
indicate seconds.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−R</b></p></td>
<td width="8%"></td>
<td width="78%">
<p><i>west, east, south,</i> and <i>north</i> specify the
Region of interest, and you may specify them in decimal
degrees or in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append
<b>r</b> if lower left and upper right map coordinates are
given instead of w/e/s/n. The two shorthands
<b>−Rg</b> and <b>−Rd</b> stand for global
domain (0/360 and -180/+180 in longitude respectively, with
-90/+90 in latitude). Alternatively, specify the name of an
existing grid file and the <b>−R</b> settings (and
grid spacing, if applicable) are copied from the grid.</p></td></tr>
</table>
<h2>OPTIONS
<a name="OPTIONS"></a>
</h2>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em"><b>−A</b></p></td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em">Add up multiple values that
belong to the same node (same as <b>−Az</b>). Append
<b>n</b> to simply count the number of data points that were
assigned to each node. [Default (no <b>−A</b> option)
will calculate mean value]. Not used for simple mapping.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−D</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Give values for <i>xname, yname, zname, scale, offset,
title,</i> and <i>remark</i>. To leave some of these values
untouched, specify = as the value.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−F</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Force pixel registration [Default is grid
registration].</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−N</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>No data. Set nodes with no input sample to this value
[Default is NaN].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−S</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>set variable spacing <i>header</i> is c for cdp, o for
offset, b<number> for 4-byte float starting at byte
number If -S not set, assumes even spacing of samples at the
dx, dy supplied with -I</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−L</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Override number of samples in each trace</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−X</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>applies scalar <i>x-scale</i> to coordinates in trace
header to match the coordinates specified in -R</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−Y</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Specifies sample interval as <i>s_int</i> if incorrect
in the SEGY file</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−M</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Fix number of traces to read in. Default tries to read
10000 traces. -M0 will read number in binary header, -Mn
will attempt to read only n traces.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−V</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Selects verbose mode, which will send progress reports
to stderr [Default runs "silently"].</p></td></tr>
</table>
<h2>EXAMPLES
<a name="EXAMPLES"></a>
</h2>
<p style="margin-left:22%; margin-top: 1em">To create a
grid file from an even spaced SEGY file test.segy, try</p>
<p style="margin-left:22%; margin-top: 1em">segy2grd
test.segy <b>−I</b> 0.1/0.1 <b>−G</b> test.grd
<b>−R</b> 198/208/18/25 <b>−V</b></p>
<p style="margin-left:22%; margin-top: 1em">Note that this
will read in 18-25s (or km) on each trace, but the first
trace will be assumed to be at X=198</p>
<p style="margin-left:22%; margin-top: 1em">To create a
grid file from the SEGY file test.segy, locating traces
according to the CDP number, where there are 10 CDPs per km
and the sample interval is 0.1, try</p>
<p style="margin-left:22%; margin-top: 1em">segy2grd
test.segy <b>−G</b> test.grd <b>−R</b>
0/100/0/10 <b>−I</b> 0.5/0.2 <b>−V −X</b>
0.1 <b>−Y</b> 0.1</p>
<p style="margin-left:22%; margin-top: 1em">Because the
grid interval is larger than the SEGY file sampling, the
individual samples will be averaged in bins</p>
<h2>SEE ALSO
<a name="SEE ALSO"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><i><A HREF="GMT.html">GMT</A></i>(1),
<i><A HREF="grd2xyz.html">grd2xyz</A></i>(1), <i><A HREF="grdedit.html">grdedit</A></i>(1), <i><A HREF="pssegy.html">pssegy</A></i>(1)</p>
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