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<title>PROJECT</title>
</head>
<body bgcolor="#ffffff">
<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>
<a name="NAME"></a>
<h2>NAME</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>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</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>
<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</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 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"><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>
</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="9%">
<p style="margin-top: 1em" valign="top"><i>infile</i></p></td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−F</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−A</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><i>azimuth</i>
defines the azimuth of the projection (Definition 1).</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−D</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−E</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><i>bx/by</i>
defines the end point of the projection path (Definition
2).</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−G</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><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 valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−H</b></p> </td>
<td width="2%"></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="9%">
<p style="margin-top: 1em" valign="top"><b>−L</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−N</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Flat Earth. Make a
Cartesian coordinate transformation in the plane. [Default
uses spherical trigonometry.]</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−Q</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−S</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Sort the output
into increasing <i>p</i> order. Useful when projecting
random data into a sequential profile.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−T</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><i>px/py</i> sets
the position of the roTation pole of the projection.
(Definition 3).</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−V</b></p> </td>
<td width="2%"></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="9%">
<p style="margin-top: 1em" valign="top"><b>−W</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−:</b></p> </td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−bi</b></p> </td>
<td width="2%"></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="9%">
<p style="margin-top: 1em" valign="top"><b>−bo</b></p> </td>
<td width="2%"></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 given by <b>−F</b> or
<b>−G</b>].</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−f</b></p> </td>
<td width="2%"></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).</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em" valign="top"><b>−m</b></p> </td>
<td width="2%"></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="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="EXAMPLES"></a>
<h2>EXAMPLES</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>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</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>
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