1GMTSTITCH(1) Generic Mapping Tools GMTSTITCH(1)
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6 gmtstitch - Join line segments whose end points match within tolerance
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9 gmtstitch [ infiles ] [ -C[closed] ] [ -D[template] ] [ -H[i][nrec] ] [
10 -L[linkfile] ] [ -Q[template] ] [ -Tcutoff[m|c|e|E|k|K][/nn_dist] ] [
11 -V ] [ -:[i|o] ] [ -b[i|o][s|S|d|D[ncol]|c[var1/...]] ] [
12 -bo[s|S|d|D[ncol]|c[var1/...]] ] [ -m[i|o][flag] ]
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15 gmtstitch reads one or more data files (which may be multisegment
16 files; see -m) and examines the coordinates of the end points of all
17 line segments. If a pair of end points are identical or closer to each
18 other than the specified separation tolerance then the two line seg‐
19 ments are joined into a single segment. The process repeats until all
20 the remaining endpoints no longer pass the tolerance test; the result‐
21 ing segments are then written out to standard output. It it is not
22 clear what the separation tolerance should be then use -L to get a list
23 of all separation distances and analyze them to determine a suitable
24 cutoff.
25 file(s)
27 One of more data files. If none are supplied then we read stan‐
28 dard input.
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31 -C Write all the closed polygons to closed [gmtstitch_closed.d] and
32 all other segments as they are to stdout. No stitching takes
33 place. Use -Tcutoff to set a minimum separation [0], and if
34 cutoff is > 0 then we also close the polygons on output.
35 -D For multiple segment data, dump each segment to a separate out‐
37 put file [Default writes a multiple segment file to stdout].
38 Append a format template for the individual file names; this
39 template must contain a C format specifier that can format an
40 integer argument (the segment number); this is usually %d but
41 could be %8.8d which gives leading zeros, etc. Optionally, it
42 may also contain the format %c before the integer; this will
43 then be replaced by C (closed) or O (open) to indicate segment
44 type. [Default is gmtstitch_segment_%d.d]. Note that segment
45 headers will be written in either case. For composite segments,
46 a generic segment header will be written and the segment headers
47 of individual pieces will be written out as comments to make it
48 possible to identify where the stitched pieces came from.
49 -H Input file(s) has header record(s). If used, the default number
51 of header records is N_HEADER_RECS. Use -Hi if only input data
52 should have header records [Default will write out header
53 records if the input data have them]. Blank lines and lines
54 starting with # are always skipped.
55 -L Writes the link information to the specified file [links.d]. For
57 each segment we write the original segment id, and for the
58 beginning and end point of the segment we report the id of the
59 closest segment, whether it is the beginning (B) or end (E)
60 point that is closest, and the distance between those points in
61 units determined by -T.
62 -Q Used with -D to a list file with the names of the individual
64 output files. Optionally, append a filename template for the
65 individual file names; this template may contain a C format
66 specifier that can format an character (C or O for closed or
67 open, respectively). [Default is gmtstitch_list.d].
68 -T Specifies the separation tolerance in the data coordinate units
70 [0]. Append m or c for minutes or seconds, or e or k for meters
71 or km (implies -fg using use flat Earth approximation. Use E or
72 K for exact geodesic distances; however. if the current ELLIP‐
73 SOID is Sphere then spherical great circle distances are used.
74 If two lines has endpoints that are closer than this cutoff they
75 will be joined. Optionally, append /nn_dist which adds the
76 requirement that a link will only be made if the second closest
77 connection exceeds the nn_dist. The latter distance is assumed
78 to be in the same units as cutoff.
79 -V Selects verbose mode, which will send progress reports to stderr
81 [Default runs "silently"].
82 -: Toggles between (longitude,latitude) and (latitude,longitude)
84 input and/or output. [Default is (longitude,latitude)]. Append
85 i to select input only or o to select output only. [Default
86 affects both].
87 -bi Selects binary input. Append s for single precision [Default is
89 d (double)]. Uppercase S or D will force byte-swapping.
90 Optionally, append ncol, the number of columns in your binary
91 input file if it exceeds the columns needed by the program. Or
92 append c if the input file is netCDF. Optionally, append
93 var1/var2/... to specify the variables to be read. [Default is
94 2 input columns].
95 -bo Selects binary output. Append s for single precision [Default
97 is d (double)]. Uppercase S or D will force byte-swapping.
98 Optionally, append ncol, the number of desired columns in your
99 binary output file. [Default is same as input].
100 -f Special formatting of input and/or output columns (time or geo‐
102 graphical data). Specify i or o to make this apply only to
103 input or output [Default applies to both]. Give one or more
104 columns (or column ranges) separated by commas. Append T (abso‐
105 lute calendar time), t (relative time in chosen TIME_UNIT since
106 TIME_EPOCH), x (longitude), y (latitude), or f (floating point)
107 to each column or column range item. Shorthand -f[i|o]g means
108 -f[i|o]0x,1y (geographic coordinates).
109 -m Multiple segment file(s). Segments are separated by a special
111 record. For ASCII files the first character must be flag
112 [Default is '>']. For binary files all fields must be NaN and
113 -b must set the number of output columns explicitly. By default
114 the -m setting applies to both input and output. Use -mi and
115 -mo to give separate settings to input and output.
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118 The ASCII output formats of numerical data are controlled by parameters
119 in your .gmtdefaults4 file. Longitude and latitude are formatted
120 according to OUTPUT_DEGREE_FORMAT, whereas other values are formatted
121 according to D_FORMAT. Be aware that the format in effect can lead to
122 loss of precision in the output, which can lead to various problems
123 downstream. If you find the output is not written with enough preci‐
124 sion, consider switching to binary output (-bo if available) or specify
125 more decimals using the D_FORMAT setting.
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128 To combine the digitized multisegment lines segment_*.d (whose coordi‐
129 nates are in cm) into as few complete lines as possible, assuming the
130 end points slop could be up to 0.1 mm, run
131 gmtstitch segment_*.d -Tf0.1 -m > new_segments.d
133 To combine the digitized segments in the multisegment file my_lines.d
135 (whose coordinates are in lon,lat) into as few complete lines as possi‐
136 ble, assuming the end points slop could be up to 150 m, and write the
137 complete segments to separate files called Map_segment_0001.dat,
138 Map_segment_0002.dat, etc., run
139 gmtstitch my_lines.d -Tf0.15k -m -DMap_segment_%4.4d.dat
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144 GMT(1), mapproject(1)
145GMT 4.5.6 10 Mar 2011 GMTSTITCH(1)