<!-- 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>GRDSPOTTER</title>
</head>
<body bgcolor="#ffffff">
<h1 align=center>GRDSPOTTER</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>
<a href="#REFERENCES">REFERENCES</a><br>
<hr>
<a name="NAME"></a>
<h2>NAME</h2>
<p style="margin-left:11%; margin-top: 1em">grdspotter
− Create CVA image directly from gravity or bathymetry
grids</p>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>
<p style="margin-left:11%; margin-top: 1em"><b>grdspotter</b>
[<i>grdfile</i>] <b>−E</b><i>rotations_file</i>
<b>−G</b><i>CVAgrid</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><i>agegrid</i> ] [
<b>−B</b><i>n_try</i> ] [ <b>−C</b> ] [
<b>−D</b><i>DIgrid</i> ] [ <b>−F</b> ] [
<b>−M</b> ] [ <b>−N</b><i>upper_age</i> ] [
<b>−P</b><i>PAgrid</i> ] [
<b>−Q</b><i>IDinfo</i> ] [ <b>−S</b> ] [
<b>−T</b> ] [ <b>−U</b><i>fixed_val</i> ] [
<b>−V</b> ] [
<b>−Z</b><i>z_min</i>[/<i>z_max</i>[/<i>z_inc</i>]]
]</p>
<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</h2>
<p style="margin-left:11%; margin-top: 1em"><b>grdspotter</b>
reads a grid file with residual bathymetry or gravity and
calculates flowlines from each node that exceeds a minimum
value using the specified rotations file. These flowlines
are then convolved with the volume of the prism represented
by each grid node and added up to give a Cumulative Volcano
Amplitude grid (CVA).</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>grdfile</i></p>
<p style="margin-left:22%;">Data grid to be processed,
typically residual bathymetry or free-air anomalies.</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>−E</b></p> </td>
<td width="4%"></td>
<td width="82%">
<p style="margin-top: 1em" valign="top">Give file with
rotation parameters. This file must contain one record for
each rotation; each record must be of the following
format:</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%"></td>
<td width="4%"></td>
<td width="82%">
<p valign="top"><i>lon lat tstart [tstop] angle</i> [
<i>khat a b c d e f g df</i> ]</p></td>
</table>
<p style="margin-left:22%; margin-top: 1em">where
<i>tstart</i> and <i>tstop</i> are in Myr and <i>lon lat
angle</i> are in degrees. <i>tstart</i> and <i>tstop</i> are
the ages of the old and young ends of a stage. If
<b>−C</b> is set then a total reconstruction rotation
is expected and <i>tstop</i> is implicitly set to 0 and
should not be specified in the file. If a covariance matrix
<b>C</b> for the rotation is available it must be specified
in a format using the nine optional terms listed in
brackets. Here, <b>C</b> = (<i>g</i>/<i>khat</i>)*[ <i>a b
d; b c e; d e f</i> ] which shows <b>C</b> made up of three
row vectors. If the degrees of freedom (<i>df</i>) in
fitting the rotation is 0 or not given it is set to 10000.
Blank lines and records whose first column contains # will
be ignored.</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">Specify name for
output CVA grid file.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−I</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><i>x_inc</i> [and
optionally <i>y_inc</i>] is the grid spacing. Optionally,
append a suffix modifier. <b>Geographical (degrees)
coordinates</b>: Append <b>m</b> to indicate arc minutes or
<b>c</b> to indicate arc seconds. If one of the units
<b>e</b>, <b>k</b>, <b>i</b>, or <b>n</b> is appended
instead, the increment is assumed to be given in meter, km,
miles, or nautical miles, respectively, and will be
converted to the equivalent degrees longitude at the middle
latitude of the region (the conversion depends on
<b><A HREF="gmtdefaults.html#ELLIPSOID">ELLIPSOID</A></b>). If /<i>y_inc</i> is given but set to 0 it
will be reset equal to <i>x_inc</i>; otherwise it will be
converted to degrees latitude. <b>All coordinates</b>: If
<b>=</b> is appended then the corresponding max <i>x</i>
(<i>east</i>) or <i>y</i> (<i>north</i>) may be slightly
adjusted to fit exactly the given increment [by default the
increment may be adjusted slightly to fit the given domain].
Finally, instead of giving an increment you may specify the
<i>number of nodes</i> desired by appending <b>+</b> to the
supplied integer argument; the increment is then
recalculated from the number of nodes and the domain. The
resulting increment value depends on whether you have
selected a gridline-registered or pixel-registered grid; see
Appendix B for details. Note: if
<b>−R</b><i>grdfile</i> is used then grid spacing has
already been initialized; use <b>−I</b> to override
the values.</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>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>
</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="3%">
<p style="margin-top: 1em" valign="top"><b>−A</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Supply a crustal
age grid that is co-registered with the input data grid.
These ages become the upper ages to use when constructing
flowlines [Default extend flowlines back to oldest age found
in the rotation file; but see <b>−N</b>].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−B</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Get <i>n_try</i>
bootstrap estimates of the maximum CVA location; the
longitude and latitude results are written to stdout
[Default is no bootstrapping]. Cannot be used with
<b>−M</b>.</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−C</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Expect Total
Reconstruction Rotations rather than Forward Stage Rotations
[Default]. File format is similar to the stage pole format
except that the <i>tstart</i> column is not present (assumed
to be 0 Ma).</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−D</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Use flowlines to
determine the maximum CVA encountered along each flowline
and create a Data Importance (DI) grid with these values at
the originating nodes.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−F</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Force pixel
registration [Default is grid registration].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−L</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Supply a
co-registered grid with seamount chain IDs for each node.
This option requires that you also use <b>−Q</b>.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−M</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Do not attempt to
keep all flowlines in memory when using <b>−D</b>
and/or <b>−P</b>. Should you run out of memory you can
use this option to compute flowlines on-the-fly. It will be
slower as we no longer can reuse the flowlines calculated
for the CVA step. Cannot be used with <b>−B</b> or the
multi-slice mode in <b>−Z</b>.</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">Set the upper age
to assign to nodes whose crustal age is unknown (i.e., NaN)
[no upper age]. Also see <b>−A</b>.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−P</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Use flowlines to
determine the flowline age at the CVA maximum for each node
and create a Predicted Age (PA) grid with these values at
the originating nodes.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−Q</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Either give (1) a
single ID to use or (2) the name of a file with a list of
IDs to use [Default uses all IDs]. Each line would be TAG ID
[w e s n]. The <i>w/e/s/n</i> zoom box is optional; if
specified it means we only trace the flowline if inside this
region [Default uses region set by <b>−R</b>].
Requires <b>−L</b>.</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">Normalize the
resulting CVA grid to percentages of the CVA maximum. This
also normalizes the DI grid (if requested).</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">Truncate crustal
ages given via the <b>−A</b> option that exceed the
upper age set with <b>−N</b> [no truncation].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−U</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">After a node passes
the test implied by <b>−Z</b>, use this
<i>fixed_val</i> instead in the calculations. [Default uses
individual node values].</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>−Z</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Ignore nodes with
z-values lower than <i>z_min</i> [0] and optionally larger
than <i>z_max</i> [Inf]. Give <i>z_min/z_max/z_inc</i> to
make separate CVA grids for each <i>z</i>-slice [Default
makes one CVA grid]. Multi-slicing cannot be used with
<b>−M</b>.</p> </td>
</table>
<a name="EXAMPLES"></a>
<h2>EXAMPLES</h2>
<p style="margin-left:11%; margin-top: 1em">To create a CVA
image from the Pacific topography grid Pac_res_topo.grd,
using the DC85.d Euler poles, and only output a grid for the
specified domain, run</p>
<p style="margin-left:11%; margin-top: 1em"><b>grdspotter</b>
Pac_res_topo.grd <b>−E</b>DC85.d
<b>−G</b>CVA.grd <b>−R</b>190/220/15/25
<b>−I</b>2<b>m −N</b>145 <b>−T
−V</b></p>
<p style="margin-left:11%; margin-top: 1em">This file can
then be plotted with <b><A HREF="grdimage.html">grdimage</A></b>.</p>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</h2>
<p style="margin-left:11%; margin-top: 1em"><i><A HREF="GMT.html">GMT</A></i>(1),
<i><A HREF="grdimage.html">grdimage</A></i>(1), <i><A HREF="project.html">project</A></i>(1), <i><A HREF="mapproject.html">mapproject</A></i>(1),
<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)</p>
<a name="REFERENCES"></a>
<h2>REFERENCES</h2>
<p style="margin-left:11%; margin-top: 1em">Wessel, P.,
1999, "Hotspotting" tools released, EOS Trans.
AGU, 80 (29), p. 319.</p>
<hr>
</body>
</html>
