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<title>PROJECT</title>
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<h1 align="center">PROJECT</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="#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">project −
project data along a line or great circle, generate a
profile track, or translate coordinates.</p>
<h2>SYNOPSIS
<a name="SYNOPSIS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>project</b>
[ <i>infile</i> ] <b>−C</b><i>cx</i>/<i>cy</i> [
<b>−A</b><i>azimuth</i> ] [ <b>−Dd</b>|<b>g</b>
] [ <b>−E</b><i>bx</i>/<i>by</i> ] [
<b>−F</b><i>flags</i> ] [ <b>−G</b><i>dist</i> ]
[ <b>−H</b>[<b>i</b>][<i>nrec</i>] ] [
<b>−L</b>[<b>w</b>][<i>l_min</i>/<i>l_max</i>] ] [
<b>−N</b> ] [ <b>−Q</b> ] [ <b>−S</b> ] [
<b>−T</b><i>px</i>/<i>py</i> ] [ <b>−V</b> ] [
<b>−W</b><i>w_min</i>/<i>w_max</i> ] [
<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>−f</b>[<b>i</b>|<b>o</b>]<i>colinfo</i> ] [
<b>−m</b>[<b>i</b>|<b>o</b>][<i>flag</i>] ]</p>
<h2>DESCRIPTION
<a name="DESCRIPTION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>project</b>
reads arbitrary (<i>x, y</i>[, <i>z</i>]) data from standard
input [or <i>infile</i> ] and writes to standard output any
combination of (<i>x, y, z, p, q, r, s</i>), where (<i>p,
q</i>) are the coordinates in the projection, (<i>r, s</i>)
is the position in the (<i>x, y</i>) coordinate system of
the point on the profile (<i>q</i> = 0 path) closest to
(<i>x, y</i>), and <i>z</i> is all remaining columns in the
input (beyond the required <i>x</i> and <i>y</i> columns).
Alternatively, <b>project</b> may be used to generate (<i>r,
s, p</i>) triples at equal increments <i>dist</i> along a
profile. In this case ( <b>−G</b> option), no input is
read. Projections are defined in any (but only) one of three
ways: (Definition 1) By a Center <b>−C</b> and an
Azimuth <b>−A</b> in degrees clockwise from North.
(Definition 2) By a Center <b>−C</b> and end point E
of the projection path <b>−E</b>. (Definition 3) By a
Center <b>−C</b> and a roTation pole position
<b>−T</b>. To spherically project data along a great
circle path, an oblique coordinate system is created which
has its equator along that path, and the zero meridian
through the Center. Then the oblique longitude (<i>p</i>)
corresponds to the distance from the Center along the great
circle, and the oblique latitude (<i>q</i>) corresponds to
the distance perpendicular to the great circle path. When
moving in the increasing (<i>p</i>) direction, (toward
<i>B</i> or in the <i>azimuth</i> direction), the positive
(<i>q</i>) direction is to your left. If a Pole has been
specified, then the positive (<i>q</i>) direction is toward
the pole. <br>
To specify an oblique projection, use the <b>−T</b>
option to set the Pole. Then the equator of the projection
is already determined and the <b>−C</b> option is used
to locate the <i>p</i> = 0 meridian. The Center <i>cx/cy</i>
will be taken as a point through which the <i>p</i> = 0
meridian passes. If you do not care to choose a particular
point, use the South pole (<i>ox</i> = 0, <i>oy</i> = -90).
<br>
Data can be selectively windowed by using the
<b>−L</b> and <b>−W</b> options. If
<b>−W</b> is used, the projection Width is set to use
only points with <i>w_min</i> < q < <i>w_max</i>. If
<b>−L</b> is set, then the Length is set to use only
those points with <i>l_min</i> < p < <i>l_max</i>. If
the <b>−E</b> option has been used to define the
projection, then <b>−Lw</b> may be selected to window
the length of the projection to exactly the span from
<b>O</b> to <b>B</b>. <br>
Flat Earth (Cartesian) coordinate transformations can also
be made. Set <b>−N</b> and remember that
<i>azimuth</i> is clockwise from North (the <i>y</i> axis),
NOT the usual cartesian theta, which is counterclockwise
from the <i>x</i> axis. <i>azimuth</i> = 90 - theta. <br>
No assumptions are made regarding the units for <i>x, y, r,
s, p, q, dist, l_min, l_max, w_min, w_max</i>. If
<b>−Q</b> is selected, map units are assumed and <i>x,
y, r, s</i> must be in degrees and <i>p, q, dist, l_min,
l_max, w_min, w_max</i> will be in km. <br>
Calculations of specific great-circle and geodesic distances
or for back-azimuths or azimuths are better done using
<b>mapproject</b>. <b><br>
project</b> is CASE SENSITIVE. Use UPPER CASE for all
one-letter designators which begin optional arguments. Use
lower case for the xyzpqrs letters in
<b>−flags</b>.</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>−C</b></p></td>
<td width="8%"></td>
<td width="78%">
<p><i>cx/cy</i> sets the origin of the projection, in
Definition 1 or 2. If Definition 3 is used
(<b>−T</b>), then <i>cx/cy</i> are the coordinates of
a point through which the oblique zero meridian (<i>p</i> =
0) should pass.</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="9%">
<p style="margin-top: 1em"><i>infile</i></p></td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em">name of ASCII (or binary, see
<b>−bi</b>) file(s) with 2 or more columns holding
(x,y,[z]) data values. If no filenames are given,
<b>project</b> will read from standard input. If the
<b>−G</b> option is selected, no input data are
read.</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−F</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Specify your desired output using any combination of
<i>xyzpqrs</i>, in any order. Do not space between the
letters. Use lower case. The output will be ASCII (or
binary, see <b>−bo</b>) columns of values
corresponding to <i>xyzpqrs</i> [Default]. If both input and
output are using ASCII format then the <i>z</i> data are
treated as textstring(s). If the <b>−G</b> option is
selected, the output will be <i>rsp</i>.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−A</b></p></td>
<td width="2%"></td>
<td width="78%">
<p><i>azimuth</i> defines the azimuth of the projection
(Definition 1).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−D</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Set the location of the Discontinuity in longitude
(<i>r</i> coordinate). <b>−Dd</b> will place the
discontinuity at the Dateline, (-180 < <i>r</i> <
180); <b>−Dg</b> will place it at Greenwich, (0 <
<i>r</i> < 360). Default usually falls at dateline due to
<i>atan2</i> calls.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−E</b></p></td>
<td width="2%"></td>
<td width="78%">
<p><i>bx/by</i> defines the end point of the projection
path (Definition 2).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−G</b></p></td>
<td width="2%"></td>
<td width="78%">
<p><i>dist</i> Generate mode. No input is read. Create
(<i>r, s, p</i>) output points every <i>dist</i> units of
<i>p</i>. See <b>−Q</b> option.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−H</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>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>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−L</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Length controls. Project only those points whose
<i>p</i> coordinate is within <i>l_min</i> < <i>p</i>
< <i>l_max</i>. If <b>−E</b> has been set, then you
may use <b>−Lw</b> to stay within the distance from
<b>C</b> to <b>E</b>.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−N</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Flat Earth. Make a Cartesian coordinate transformation
in the plane. [Default uses spherical trigonometry.]</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−Q</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Map type units, i.e., project assumes <i>x, y, r, s</i>
are in degrees while <i>p, q, dist, l_min, l_max, w_min,
w_max</i> are in km. If <b>−Q</b> is not set, then all
these are assumed to be in the same units.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−S</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Sort the output into increasing <i>p</i> order. Useful
when projecting random data into a sequential profile.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−T</b></p></td>
<td width="2%"></td>
<td width="78%">
<p><i>px/py</i> sets the position of the roTation pole of
the projection. (Definition 3).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−V</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Selects verbose mode, which will send progress reports
to stderr [Default runs "silently"].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−W</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Width controls. Project only those points whose <i>q</i>
coordinate is within <i>w_min</i> < <i>q</i> <
<i>w_max</i>.</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−:</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Toggles between (longitude,latitude) and
(latitude,longitude) input and/or output. [Default is
(longitude,latitude)]. Append <b>i</b> to select input only
or <b>o</b> to select output only. [Default affects
both].</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−bi</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>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>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−bo</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>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 given by <b>−F</b> or
<b>−G</b>].</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−f</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>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).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>−m</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>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></tr>
</table>
<h2>ASCII FORMAT PRECISION
<a name="ASCII FORMAT PRECISION"></a>
</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>
<h2>EXAMPLES
<a name="EXAMPLES"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">To generate
points every 10km along a great circle from 10N,50W to
30N,10W:</p>
<p style="margin-left:11%; margin-top: 1em"><b>project
−C</b>-50/10 <b>−E</b>-10/30 <b>−G</b> 10
<b>−Q</b> > great_circle_points.xyp</p>
<p style="margin-left:11%; margin-top: 1em">(Note that
great_circle_points.xyp could now be used as input for
<b><A HREF="grdtrack.html">grdtrack</A></b>, etc. ).</p>
<p style="margin-left:11%; margin-top: 1em">To project the
shiptrack gravity, magnetics, and bathymetry in c2610.xygmb
along a great circle through an origin at 30S, 30W, the
great circle having an azimuth of N20W at the origin,
keeping only the data from NE of the profile and within +/-
500 km of the origin, run:</p>
<p style="margin-left:11%; margin-top: 1em"><b>project</b>
c2610.xygmb <b>−C</b>-30/-30 <b>−A</b>-20
<b>−W</b>-10000/0 <b>−L</b>-500/500
<b>−F</b> pz <b>−Q</b> >
c2610_projected.pgmb</p>
<p style="margin-left:11%; margin-top: 1em">(Note in this
example that <b>−W</b>-10000/0 is used to admit any
value with a large negative <i>q</i> coordinate. This will
take those points which are on our right as we walk along
the great circle path, or to the NE in this example.)</p>
<p style="margin-left:11%; margin-top: 1em">To make a
Cartesian coordinate transformation of mydata.xy so that the
new origin is at 5,3 and the new <i>x</i> axis (<i>p</i>)
makes an angle of 20 degrees with the old <i>x</i> axis,
use:</p>
<p style="margin-left:11%; margin-top: 1em"><b>project</b>
mydata.xy <b>−C</b> 5/3 <b>−A</b> 70
<b>−F</b> pq > mydata.pq</p>
<p style="margin-left:11%; margin-top: 1em">To take data in
the file pacific.lonlat and transform it into oblique
coordinates using a pole from the hotspot reference frame
and placing the oblique zero meridian (<i>p</i> = 0 line)
through Tahiti, run:</p>
<p style="margin-left:11%; margin-top: 1em"><b>project</b>
pacific.lonlat <b>−T</b>-75/68
<b>−C</b>-149:26/-17:37 <b>−F</b> pq >
pacific.pq</p>
<p style="margin-left:11%; margin-top: 1em">Suppose that
pacific_topo.grd is a grid file of bathymetry, and you want
to make a file of flowlines in the hotspot reference frame.
If you run:</p>
<p style="margin-left:11%; margin-top: 1em"><b><A HREF="grd2xyz.html">grd2xyz</A></b>
pacific_topo.grd | <b>project −T</b>-75/68
<b>−C</b> 0/-90 <b>−F</b> xyq | <b>xyz2grd
−R</b><i>etc</i> <b>−I</b><i>etc</i>
<b>−C</b> flow.grd</p>
<p style="margin-left:11%; margin-top: 1em">then flow.grd
is a file in the same area as pacific_topo.grd, but flow
contains the latitudes about the pole of the projection. You
now can use grdcontour on flow.grd to draw lines of constant
oblique latitude, which are flow lines in the hotspot
frame.</p>
<p style="margin-left:11%; margin-top: 1em">If you have an
arbitrarily rotation pole <i>px/py</i> and you would like to
draw an oblique small circle on a map, you will first need
to make a file with the oblique coordinates for the small
circle (i.e., lon = 0−360, lat is constant), then
create a file with two records: the north pole (0/90) and
the origin (0/0), and find what their oblique coordinates
are using your rotation pole. Now, use the projected North
pole and origin coordinates as the rotation pole and center,
respectively, and project your file as in the pacific
example above. This gives coordinates for an oblique small
circle.</p>
<h2>SEE ALSO
<a name="SEE ALSO"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><i><A HREF="fitcircle.html">fitcircle</A></i>(1),
<i><A HREF="GMT.html">GMT</A></i>(1), <i>mapproject</i>(1),
<i>grdproject</i>(1)</p>
<hr>
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