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<title>GRD2XYZ</title>
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<h1 align=center>GRD2XYZ</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="#ASCII FORMAT PRECISION">ASCII FORMAT PRECISION</a><br>
<a href="#GRID FILE FORMATS">GRID FILE FORMATS</a><br>
<a href="#TIME COORDINATES">TIME COORDINATES</a><br>
<a href="#EXAMPLES">EXAMPLES</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<hr>
<a name="NAME"></a>
<h2>NAME</h2>
<p style="margin-left:11%; margin-top: 1em">grd2xyz −
Converting grid file(s) to ASCII or binary data</p>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>
<p style="margin-left:11%; margin-top: 1em"><b>grd2xyz</b>
<i>grdfiles</i> [ <b>−E</b>[<i>nodata</i>] ] [
<b>−H</b>[<b>i</b>][<i>nrec</i>] ] [
<b>−N</b><i>nodata</i> ] [
<b>−R</b><i>west</i>/<i>east</i>/<i>south</i>/<i>north</i>[<b>r</b>]
] [ <b>−S</b>[<b>r</b>] ] [ <b>−V</b> ] [
<b>−W</b>[<i>weight</i>] ] [
<b>−Z</b>[<i>flags</i>] ] [
<b>−bo</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>]]
] [ <b>−f</b><i>colinfo</i> ]</p>
<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</h2>
<p style="margin-left:11%; margin-top: 1em"><b>grd2xyz</b>
reads one or more binary 2-D grid files and writes out
xyz-triplets in ASCII [or binary] format to standard output.
Modify the precision of the ASCII output format by editing
the <b><A HREF="gmtdefaults.html#D_FORMAT">D_FORMAT</A></b> parameter in your .gmtdefaults4 file or
use <b>−−D_FORMAT</b>=<i>value</i> on the
command line, or choose binary output using single or double
precision storage. As an option you may output z-values
without the (x,y) in a number of formats, see
<b>−E</b> or <b>−Z</b> below. <i><br>
grdfiles</i></p>
<p style="margin-left:22%;">Names of 2-D binary grid files
to be converted. (See GRID FILE FORMATS below.)</p>
<a name="OPTIONS"></a>
<h2>OPTIONS</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" valign="top"><b>−E</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Output an ESRI
ArcInfo ASCII interchange grid format file. Append
<i>nodata</i> which will be used wherever the grid value
equals NaN [-9999]. Note that all data values are written as
integers.</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−H</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Output 1 header
record based on information in the first grid file header.
Ignored if binary output is selected. [Default is no
header].</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−N</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Output this z-value
where the latter equals NaN [Default writes NaN].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−R</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><i>xmin</i>,
<i>xmax</i>, <i>ymin</i>, and <i>ymax</i> specify the Region
of interest. For geographic regions, these limits correspond
to <i>west, east, south,</i> and <i>north</i> 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. For
calendar time coordinates you may either give (a) relative
time (relative to the selected <b><A HREF="gmtdefaults.html#TIME_EPOCH">TIME_EPOCH</A></b> and in the
selected <b><A HREF="gmtdefaults.html#TIME_UNIT">TIME_UNIT</A></b>; append <b>t</b> to
<b>−JX</b>|<b>x</b>), or (b) absolute time of the form
[<i>date</i>]<b>T</b>[<i>clock</i>] (append <b>T</b> to
<b>−JX</b>|<b>x</b>). At least one of <i>date</i> and
<i>clock</i> must be present; the <b>T</b> is always
required. The <i>date</i> string must be of the form
[-]yyyy[-mm[-dd]] (Gregorian calendar) or yyyy[-Www[-d]]
(ISO week calendar), while the <i>clock</i> string must be
of the form hh:mm:ss[.xxx]. The use of delimiters and their
type and positions must be exactly as indicated (however,
input, output and plot formats are customizable; see
<b><A HREF="gmtdefaults.html">gmtdefaults</A></b>). Using the <b>−R</b> option will
select a subsection of the grid. If this subsection exceeds
the boundaries of the grid, only the common region will be
output.</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−S</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Suppress output for
nodes whose z-value equals NaN [Default outputs all nodes].
Append <b>r</b> to reverse the suppression, i.e., only
output the nodes whose z-value equals NaN.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−V</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Selects verbose
mode, which will send progress reports to stderr [Default
runs "silently"].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−W</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Write out x,y,z,w,
where w is the supplied <i>weight</i> (or 1 if not supplied)
[Default writes x,y,z only].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−Z</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Write a 1-column
ASCII [or binary] table. Output will be organized according
to the specified ordering convention contained in
<i>flags</i>. If data should be written by rows, make
<i>flags</i> start with <b>T</b>(op) if first row is y =
ymax or <b>B</b>(ottom) if first row is y = ymin. Then,
append <b>L</b> or <b>R</b> to indicate that first element
should start at left or right end of row. Likewise for
column formats: start with <b>L</b> or <b>R</b> to position
first column, and then append <b>T</b> or <b>B</b> to
position first element in a row. For gridline registered
grids: If grid is periodic in x but the outcoming data
should not contain the (redundant) column at x = xmax,
append <b>x</b>. For grid periodic in y, skip writing the
redundant row at y = ymax by appending <b>y</b>. If the
byte-order needs to be swapped, append <b>w</b>. Select one
of several data types (all binary except <b>a</b>):</p></td>
</table>
<p style="margin-left:22%; margin-top: 1em"><b>a</b> ASCII
representation <b><br>
c</b> signed 1-byte character <b><br>
u</b> unsigned 1-byte character <b><br>
h</b> short 2-byte integer <b><br>
i</b> 4-byte integer <b><br>
l</b> long (4- or 8-byte) integer [architecture-dependent!]
<b><br>
f</b> 4-byte floating point single precision <b><br>
d</b> 8-byte floating point double precision</p>
<p style="margin-left:22%; margin-top: 1em">Default format
is scanline orientation of ASCII numbers:
<b>−ZTLa</b>. Note that <b>−Z</b> only applies
to 1-column output.</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="4%">
<p style="margin-top: 1em" valign="top"><b>−bo</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Selects binary
output. Append <b>s</b> for single precision [Default is
<b>d</b> (double)]. Uppercase <b>S</b> or <b>D</b> will
force byte-swapping. Optionally, append <i>ncol</i>, the
number of desired columns in your binary output file.
[Default is 3]. This option only applies to xyz output; see
<b>−Z</b> for z table output.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−f</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Special formatting
of input and/or output columns (time or geographical data).
Specify <b>i</b> or <b>o</b> to make this apply only to
input or output [Default applies to both]. Give one or more
columns (or column ranges) separated by commas. Append
<b>T</b> (absolute calendar time), <b>t</b> (relative time
in chosen <b><A HREF="gmtdefaults.html#TIME_UNIT">TIME_UNIT</A></b> since <b><A HREF="gmtdefaults.html#TIME_EPOCH">TIME_EPOCH</A></b>),
<b>x</b> (longitude), <b>y</b> (latitude), or <b>f</b>
(floating point) to each column or column range item.
Shorthand <b>−f</b>[<b>i</b>|<b>o</b>]<b>g</b> means
<b>−f</b>[<b>i</b>|<b>o</b>]0<b>x</b>,1<b>y</b>
(geographic coordinates). See also <b>TIME COORDINATES</b>
below.</p> </td>
</table>
<a name="ASCII FORMAT PRECISION"></a>
<h2>ASCII FORMAT PRECISION</h2>
<p style="margin-left:11%; margin-top: 1em">The ASCII
output formats of numerical data are controlled by
parameters in your .gmtdefaults4 file. Longitude and
latitude are formatted according to
<b><A HREF="gmtdefaults.html#OUTPUT_DEGREE_FORMAT">OUTPUT_DEGREE_FORMAT</A></b>, whereas other values are
formatted according to <b><A HREF="gmtdefaults.html#D_FORMAT">D_FORMAT</A></b>. Be aware that the
format in effect can lead to loss of precision in the
output, which can lead to various problems downstream. If
you find the output is not written with enough precision,
consider switching to binary output (<b>−bo</b> if
available) or specify more decimals using the
<b><A HREF="gmtdefaults.html#D_FORMAT">D_FORMAT</A></b> setting.</p>
<a name="GRID FILE FORMATS"></a>
<h2>GRID FILE FORMATS</h2>
<p style="margin-left:11%; margin-top: 1em"><b><A HREF="GMT.html">GMT</A></b> is
able to recognize many of the commonly used grid file
formats, as well as the precision, scale and offset of the
values contained in the grid file. When <b><A HREF="GMT.html">GMT</A></b> needs a
little help with that, you can add the suffix
<b>=</b><i>id</i>[<b>/</b><i>scale</i><b>/</b><i>offset</i>[<b>/</b><i>nan</i>]],
where <i>id</i> is a two-letter identifier of the grid type
and precision, and <i>scale</i> and <i>offset</i> are
optional scale factor and offset to be applied to all grid
values, and <i>nan</i> is the value used to indicate missing
data. See <b><A HREF="grdreformat.html">grdreformat</A></b>(1) and Section 4.17 of the GMT
Technical Reference and Cookbook for more information.</p>
<p style="margin-left:11%; margin-top: 1em">When reading a
netCDF file that contains multiple grids, <b><A HREF="GMT.html">GMT</A></b> will
read, by default, the first 2-dimensional grid that can find
in that file. To coax <b><A HREF="GMT.html">GMT</A></b> into reading another
multi-dimensional variable in the grid file, append
<b>?</b><i>varname</i> to the file name, where
<i>varname</i> is the name of the variable. Note that you
may need to escape the special meaning of <b>?</b> in your
shell program by putting a backslash in front of it, or by
placing the filename and suffix between quotes or double
quotes. See <b><A HREF="grdreformat.html">grdreformat</A></b>(1) and Section 4.18 of the
GMT Technical Reference and Cookbook for more information,
particularly on how to read splices of 3-, 4-, or
5-dimensional grids.</p>
<a name="TIME COORDINATES"></a>
<h2>TIME COORDINATES</h2>
<p style="margin-left:11%; margin-top: 1em">Time
coordinates in netCDF grids, be it the x, y, or z
coordinate, will be recognized as such. The variable’s
<b>unit</b> attribute is parsed to determine the unit and
epoch of the time coordinate in the grid. Values are then
converted to the internal time system specified by
<b><A HREF="gmtdefaults.html#TIME_UNIT">TIME_UNIT</A></b> and <b><A HREF="gmtdefaults.html#TIME_EPOCH">TIME_EPOCH</A></b> in the .gmtdefaults
file or on the command line. The default output is relative
time in that time system, or absolute time when using the
option <b>−f0T</b>, <b>−f1T</b>, or
<b>−f2T</b> for x, y, or z coordinate,
respectively.</p>
<a name="EXAMPLES"></a>
<h2>EXAMPLES</h2>
<p style="margin-left:11%; margin-top: 1em">To edit
individual values in the 5’ by 5’ hawaii_grv.grd
file, dump the .grd to ASCII:</p>
<p style="margin-left:11%; margin-top: 1em"><b>grd2xyz</b>
hawaii_grv.grd > hawaii_grv.xyz</p>
<p style="margin-left:11%; margin-top: 1em">To write a
single precision binary file without the x,y positions from
the file raw_data.grd file, using scanline orientation,
run</p>
<p style="margin-left:11%; margin-top: 1em"><b>grd2xyz</b>
raw_data.grd <b>−ZTLf</b> > hawaii_grv.b</p>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</h2>
<p style="margin-left:11%; margin-top: 1em"><i><A HREF="gmtdefaults.html">gmtdefaults</A></i>(1),
<i><A HREF="GMT.html">GMT</A></i>(1), <i><A HREF="grdedit.html">grdedit</A></i>(1), <i><A HREF="xyz2grd.html">xyz2grd</A></i>(1)</p>
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