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<title>GMTSTITCH</title>
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<h1 align=center>GMTSTITCH</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">gmtstitch
− Join line segments whose end points match within
tolerance</p>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>
<p style="margin-left:11%; margin-top: 1em"><b>gmtstitch</b>
[ <i>infiles</i> ] [ <b>−C</b>[<i>closed</i>] ] [
<b>−D</b>[<i>template</i>] ] [
<b>−H</b>[<b>i</b>][<i>nrec</i>] ] [
<b>−L</b>[<i>linkfile</i>] ] [
<b>−Q</b>[<i>template</i>] ] [
<b>−T</b><i>cutoff</i>[<b>m</b>|<b>c</b>|<b>e</b>|<b>E</b>|<b>k</b>|<b>K</b>][/<i>nn_dist</i>]
] [ <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>−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>−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>gmtstitch</b>
reads one or more data files (which may be multisegment
files; see <b>−m</b>) and examines the coordinates of
the end points of all line segments. If a pair of end points
are identical or closer to each other than the specified
separation tolerance then the two line segments are joined
into a single segment. The process repeats until all the
remaining endpoints no longer pass the tolerance test; the
resulting segments are then written out to standard output.
It it is not clear what the separation tolerance should be
then use <b>−L</b> to get a list of all separation
distances and analyze them to determine a suitable cutoff.
<i><br>
file(s)</i></p>
<p style="margin-left:22%;">One of more data files. If none
are supplied then we read standard input.</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="4%">
<p style="margin-top: 1em" valign="top"><b>−C</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Write all the
closed polygons to <i>closed</i> [gmtstitch_closed.d] and
all other segments as they are to stdout. No stitching takes
place. Use <b>−T</b><i>cutoff</i> to set a minimum
separation [0], and if <i>cutoff</i> is > 0 then we also
close the polygons on output.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−D</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">For multiple
segment data, dump each segment to a separate output file
[Default writes a multiple segment file to stdout]. Append a
format template for the individual file names; this template
<b>must</b> contain a C format specifier that can format an
integer argument (the segment number); this is usually %d
but could be %8.8d which gives leading zeros, etc.
Optionally, it may also contain the format %c <i>before</i>
the integer; this will then be replaced by C (closed) or O
(open) to indicate segment type. [Default is
gmtstitch_segment_%d.d]. Note that segment headers will be
written in either case. For composite segments, a generic
segment header will be written and the segment headers of
individual pieces will be written out as comments to make it
possible to identify where the stitched pieces came
from.</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>−L</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Writes the link
information to the specified file [links.d]. For each
segment we write the original segment id, and for the
beginning and end point of the segment we report the id of
the closest segment, whether it is the beginning (B) or end
(E) point that is closest, and the distance between those
points in units determined by <b>−T</b>.</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">Used with
<b>−D</b> to a list file with the names of the
individual output files. Optionally, append a filename
template for the individual file names; this template
<b>may</b> contain a C format specifier that can format an
character (C or O for closed or open, respectively).
[Default is gmtstitch_list.d].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−T</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Specifies the
separation tolerance in the data coordinate units [0].
Append <b>m</b> or <b>c</b> for minutes or seconds, or
<b>e</b> or <b>k</b> for meters or km (implies
<b>−fg</b> using use flat Earth approximation. Use
<b>E</b> or <b>K</b> for exact geodesic distances; however.
if the current ELLIPSOID is Sphere then spherical great
circle distances are used. If two lines has endpoints that
are closer than this cutoff they will be joined. Optionally,
append /<i>nn_dist</i> which adds the requirement that a
link will only be made if the second closest connection
exceeds the <i>nn_dist</i>. The latter distance is assumed
to be in the same units as <i>cutoff</i>.</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 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="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>−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).</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="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 combine the
digitized multisegment lines segment_*.d (whose coordinates
are in cm) into as few complete lines as possible, assuming
the end points slop could be up to 0.1 mm, run</p>
<p style="margin-left:11%; margin-top: 1em"><b>gmtstitch</b>
segment_*.d <b>−Tf</b>0.1 <b>−m</b> >
new_segments.d</p>
<p style="margin-left:11%; margin-top: 1em">To combine the
digitized segments in the multisegment file my_lines.d
(whose coordinates are in lon,lat) into as few complete
lines as possible, assuming the end points slop could be up
to 150 m, and write the complete segments to separate files
called Map_segment_0001.dat, Map_segment_0002.dat, etc.,
run</p>
<p style="margin-left:11%; margin-top: 1em"><b>gmtstitch</b>
my_lines.d <b>−Tf</b>0.15k <b>−m
−D</b>Map_segment_%4.4d.dat</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="mapproject.html">mapproject</A></i>(1)</p>
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