<!-- Creator : groff version 1.19.2 -->
<!-- CreationDate: Thu Jan 14 08:19:50 2010 -->
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta name="generator" content="groff -Thtml, see www.gnu.org">
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<meta name="Content-Style" content="text/css">
<style type="text/css">
p { margin-top: 0; margin-bottom: 0; }
pre { margin-top: 0; margin-bottom: 0; }
table { margin-top: 0; margin-bottom: 0; }
</style>
<title>GRDROTATER</title>
</head>
<body bgcolor="#ffffff">
<h1 align=center>GRDROTATER</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>
<a name="NAME"></a>
<h2>NAME</h2>
<p style="margin-left:11%; margin-top: 1em">grdrotater
− Rotate a grid using a finite rotation</p>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>
<p style="margin-left:11%; margin-top: 1em"><b>grdrotate</b>
<i>ingrdfile</i> <b>−G</b><i>outgrdfile</i>
<b>−T</b><i>plon</i>/<i>plat</i>/<i>omega</i> [
<b>−F</b><i>polygonfile</i> ] [
<b>−H</b>[<b>i</b>][<i>nrec</i>] ] [ <b>−N</b> ]
[
<b>−Q</b>[<b>b</b>|<b>c</b>|<b>l</b>|<b>n</b>][[<b>/</b>]<i>threshold</i>]
] [
<b>−R</b><i>west</i>/<i>east</i>/<i>south</i>/<i>north</i>[<b>r</b>]
] [ <b>−S</b> ] [ <b>−V</b> ] [
<b>−:</b>[<b>i</b>|<b>o</b>] ] [
<b>−b</b>[<b>i</b>|<b>o</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>−m</b>[<i>flag</i>] ]</p>
<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</h2>
<p style="margin-left:11%; margin-top: 1em"><b>grdrotater</b>
reads a geographical grid and reconstructs it given a total
reconstruction rotation. Optionally, the user may supply a
clipping polygon in multiple-segment format; then, only the
part of the grid inside the polygon is used to determine the
return grid region. The outline of the projected region is
returned on stdout.</p>
<table width="100%" border=0 rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="8%"></td>
<td width="7%"></td>
<td width="85%">
<p valign="top">No space between the option flag and the
associated arguments. Use upper case for the option flags
and lower case for modifiers.</p></td>
</table>
<p style="margin-left:11%;"><i>ingrdfile</i></p>
<p style="margin-left:22%;">Name of a grid file in
geographical (lon, lat) coordinates.</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 style="margin-top: 1em" valign="top"><b>−G</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Name of output
grid. This is the grid with the data reconstructed according
to the specified rotation.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−T</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Finite rotation.
Specify the longitude and latitude of the rotation pole and
the opening angle, all in degrees.</p></td>
</table>
<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="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">Specify a
multi-segment closed polygon file that describes the inside
area of the grid that should be projected [Default projects
entire grid].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−H</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Input file(s) has
header record(s). If used, the default number of header
records is <b><A HREF="gmtdefaults.html#N_HEADER_RECS">N_HEADER_RECS</A></b>. Use <b>−Hi</b> if
only input data should have header records [Default will
write out header records if the input data have them]. Blank
lines and lines starting with # are always skipped.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−N</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Do Not output the
rotated polygon outline [Default will write it to
stdout].</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−Q</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Quick mode, use
bilinear rather than bicubic interpolation [Default].
Alternatively, select the interpolation mode by adding
<b>b</b> for B-spline smoothing, <b>c</b> for bicubic
interpolation, <b>l</b> for bilinear interpolation or
<b>n</b> for nearest-neighbor value. Optionally, append
<i>threshold</i> in the range [0,1]. This parameter controls
how close to nodes with NaN values the interpolation will
go. E.g., a <i>threshold</i> of 0.5 will interpolate about
half way from a non-NaN to a NaN node, whereas 0.1 will go
about 90% of the way, etc. [Default is 1, which means none
of the (4 or 16) nearby nodes may be NaN]. <b>−Q0</b>
will just return the value of the nearest node instead of
interpolating. This is the same as using
<b>−Qn</b>.</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−R</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><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 valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−S</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Skip the rotation
of the grid, just rotate the polygon outline (requires
<b>−F</b>).</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−V</b></p> </td>
<td width="7%"></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="4%">
<p style="margin-top: 1em" valign="top"><b>−:</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Toggles between
(longitude,latitude) and (latitude,longitude) input/output.
[Default is (longitude,latitude)].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−bi</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Selects binary
input. 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 columns in your binary input file if it exceeds
the columns needed by the program. Or append <b>c</b> if the
input file is netCDF. Optionally, append
<i>var1</i><b>/</b><i>var2</i><b>/</b><i>...</i> to specify
the variables to be read. [Default is 2 input columns].</p></td>
<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 same as input].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−m</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Multiple segment
file(s). Segments are separated by a special record. For
ASCII files the first character must be <i>flag</i> [Default
is ’>’]. For binary files all fields must be
NaN and <b>−b</b> must set the number of output
columns explicitly. By default the <b>−m</b> setting
applies to both input and output. Use <b>−mi</b> and
<b>−mo</b> to give separate settings to input and
output.</p> </td>
</table>
<a name="EXAMPLES"></a>
<h2>EXAMPLES</h2>
<p style="margin-left:11%; margin-top: 1em">To rotate the
data defined by grid topo.grd and the polygon outline
clip_path.d, using a finite rotation with pole at (135.5,
-33.0) and a rotation angle of 37.3 degrees and bicubic
interpolation, try</p>
<p style="margin-left:11%; margin-top: 1em"><b>grdrotater</b>
topo.grd <b>−T</b>135.5/-33/37.3 <b>−V
−F</b>clip_path.d <b>−G</b>rot_topo.grd >
rot_clip_path.d</p>
<p style="margin-left:11%; margin-top: 1em">To rotate the
entire grid faa.grd using a finite rotation pole at (67:45W,
22:35S) and a rotation angle of 19.6 degrees using a
bilinear interpolation, try</p>
<p style="margin-left:11%; margin-top: 1em"><b>grdrotater</b>
faa.grd <b>−T</b>67:45W/22:35S/19.6 <b>−V
−Q −G</b>rot_faa.grd > rot_faa_path.d</p>
<p style="margin-left:11%; margin-top: 1em">To just see how
the outline of the grid large.grd will plot after the same
rotation, try</p>
<p style="margin-left:11%; margin-top: 1em"><b>grdrotater</b>
large.grd <b>−T</b>67:45W/22:35S/19.6 <b>−V
−S</b> | psxy <b>−Rg −JH</b>180/6i
<b>−B</b>30 <b>−m −W</b>0.5<b>p</b> | gv
-</p>
<p style="margin-left:11%; margin-top: 1em">Let say you
have rotated gridA.grd and gridB.grd, restricting each
rotation to nodes inside polygons polyA.d and polyB.d,
respectively, using rotation A = (123W,22S,16,4) and
rotation B = (108W, 16S, -14.5), yielding rotated grids
rot_gridA.grd and rot_gridB.grd. To determine the region of
overlap between the rotated grids, we use grdmath:</p>
<p style="margin-left:11%; margin-top: 1em">grdmath 1
rot_gridA.grd ISNAN SUB 1 rot_gridB.grd ISNAN SUB 2 EQ =
overlap.grd</p>
<p style="margin-left:11%; margin-top: 1em">The grid
overlap.grd now has 1s in the regions of overlap and 0
elsewhere. You can use it as a mask or use grdcontour to
extract a polygon (contour).</p>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</h2>
<p style="margin-left:11%; margin-top: 1em"><i><A HREF="backtracker.html">backtracker</A></i>(1),
<i><A HREF="hotspotter.html">hotspotter</A></i>(1), <i><A HREF="originator.html">originator</A></i>(1)
<i><A HREF="rotconverter.html">rotconverter</A></i>(1)</p>
<hr>
</body>
</html>
