GMTSTITCH(1gmt) 					       Generic Mapping Tools						   GMTSTITCH(1gmt)

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 for-
	      mat %c before the integer; this will then be replaced by C (closed) or  O  (open)  to  indicate  segment	type.	[Default  is  gmt-
	      stitch_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 begin-
	      ning 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 individ-
	      ual file names; this template may contain a C format specifier that can format an character (C or O  for	closed	or  open,  respec-
	      tively). [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.   Option-
	      ally,  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.   Option-
	      ally, 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  pre-
       cision, 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 -Tf0.1 -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 pos-
       sible,  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 -Tf0.15k -m -DMap_segment_%4.4d.dat

SEE ALSO

       GMT(1), mapproject(1)

GMT 4.5.7							    15 Jul 2011 						   GMTSTITCH(1gmt)