Provided by: gmt_4.5.11-1build1_amd64 
NAME
gmtstitch - Join line segments whose end points match within tolerance
SYNOPSIS
gmtstitch [ infiles ] [ -C[closed] ] [ -D[template] ] [ -H[i][nrec] ] [ -L[linkfile] ] [ -Q[template] ] [
-Tcutoff[m|c|e|E|k|K][/nn_dist] ] [ -V ] [ -:[i|o] ] [ -b[i|o][s|S|d|D[ncol]|c[var1/...]] ] [
-bo[s|S|d|D[ncol]|c[var1/...]] ] [ -m[i|o][flag] ]
DESCRIPTION
gmtstitch reads one or more data files (which may be multisegment files; see -m) 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 -L to get a list of all separation distances and analyze them to determine a
suitable cutoff.
file(s)
One of more data files. If none are supplied then we read standard input.
OPTIONS
-C Write all the closed polygons to closed [gmtstitch_closed.d] and all other segments as they are to
stdout. No stitching takes place. Use -Tcutoff to set a minimum separation [0], and if cutoff is
> 0 then we also close the polygons on output.
-D 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
must 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 before 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.
-H Input file(s) has header record(s). If used, the default number of header records is
N_HEADER_RECS. Use -Hi 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.
-L 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 -T.
-Q Used with -D to a list file with the names of the individual output files. Optionally, append a
filename template for the individual file names; this template may contain a C format specifier
that can format an character (C or O for closed or open, respectively). [Default is
gmtstitch_list.d].
-T Specifies the separation tolerance in the data coordinate units [0]. Append m or c for minutes or
seconds, or e or k for meters or km (implies -fg using use flat Earth approximation. Use E or K
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 /nn_dist which adds the requirement that a link will only be made
if the second closest connection exceeds the nn_dist. The latter distance is assumed to be in the
same units as cutoff.
-V Selects verbose mode, which will send progress reports to stderr [Default runs "silently"].
-: Toggles between (longitude,latitude) and (latitude,longitude) input and/or output. [Default is
(longitude,latitude)]. Append i to select input only or o to select output only. [Default
affects both].
-bi Selects binary input. Append s for single precision [Default is d (double)]. Uppercase S or D
will force byte-swapping. Optionally, append ncol, the number of columns in your binary input
file if it exceeds the columns needed by the program. Or append c if the input file is netCDF.
Optionally, append var1/var2/... to specify the variables to be read. [Default is 2 input
columns].
-bo Selects binary output. Append s for single precision [Default is d (double)]. Uppercase S or D
will force byte-swapping. Optionally, append ncol, the number of desired columns in your binary
output file. [Default is same as input].
-f Special formatting of input and/or output columns (time or geographical data). Specify i or o 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 T (absolute calendar time), t (relative time in chosen
TIME_UNIT since TIME_EPOCH), x (longitude), y (latitude), or f (floating point) to each column or
column range item. Shorthand -f[i|o]g means -f[i|o]0x,1y (geographic coordinates).
-m Multiple segment file(s). Segments are separated by a special record. For ASCII files the first
character must be flag [Default is '>']. For binary files all fields must be NaN and -b must set
the number of output columns explicitly. By default the -m setting applies to both input and
output. Use -mi and -mo to give separate settings to input and output.
ASCII FORMAT PRECISION
The ASCII output formats of numerical data are controlled by parameters in your .gmtdefaults4 file.
Longitude and latitude are formatted according to OUTPUT_DEGREE_FORMAT, whereas other values are
formatted according to D_FORMAT. 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 (-bo if available) or specify more decimals using the
D_FORMAT setting.
EXAMPLES
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
gmtstitch segment_*.d -Tf 0.1 -m > new_segments.d
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
gmtstitch my_lines.d -Tf 0.15k -m -D Map_segment_%4.4d.dat
BUGS
The line connection does not work if a line only has a single point. However, gmtstitch will correctly
add the point to the nearest segment. Running gmtstitch again on the new set of lines will eventually
connect all close lines.
SEE ALSO
GMT(1), mapproject(1)
GMT 4.5.11 5 Nov 2013 GMTSTITCH(1gmt)