i.gensig(1grass)

1i.gensig(1)                   Grass User's Manual                  i.gensig(1)
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NAME

6       i.gensig  - Generates statistics for i.maxlik from raster map.
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KEYWORDS

9       imagery,  classification, supervised classification, Maximum Likelihood
10       Classification, MLC, signatures
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SYNOPSIS

13       i.gensig
14       i.gensig --help
15       i.gensig trainingmap=name group=name  subgroup=name  signaturefile=name
16       [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]
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18   Flags:
19       --overwrite
20           Allow output files to overwrite existing files
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22       --help
23           Print usage summary
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25       --verbose
26           Verbose module output
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28       --quiet
29           Quiet module output
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31       --ui
32           Force launching GUI dialog
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34   Parameters:
35       trainingmap=name [required]
36           Ground truth training map
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38       group=name [required]
39           Name of input imagery group
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41       subgroup=name [required]
42           Name of input imagery subgroup
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44       signaturefile=name [required]
45           Name for output file containing result signatures
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DESCRIPTION

48       i.gensig  is  a non-interactive method for generating input into i.max‐
49       lik.  It can be used as the first pass in the GRASS two-pass  classifi‐
50       cation  process  (instead  of  i.cluster  or g.gui.iclass).  It reads a
51       raster map layer, called the training map, which has some of the pixels
52       or  regions  already  classified.   i.gensig will then extract spectral
53       signatures from an image based on the classification of the  pixels  in
54       the training map and make these signatures available to i.maxlik.
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56       The user would then execute the GRASS program i.maxlik to actually cre‐
57       ate the final classified map.
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OPTIONS

60   Parameters
61       trainingmap=name
62           ground truth training map
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64       This map must be prepared by the user in advance using vector or raster
65       digitizer.  Of  course  other  methods could be devised by the user for
66       creating this training map - i.gensig makes  no  assumption  about  the
67       origin  of this map layer. It simply creates signatures for the classes
68       defined in the training map for the image to be classified  (the  image
69       is  specified in other options - see below). The wxGUI vector digitizer
70       can be used for interactively creating the training map.
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72       group=name
73           imagery group
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75       This is the name of the group that contains the band files  which  com‐
76       prise  the  image  to be analyzed. The i.group  command is used to con‐
77       struct groups of raster layers which comprise an image.
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79       subgroup=name
80           subgroup containing image files
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82       This names the subgroup within the group that selects a subset  of  the
83       bands to be analyzed. The i.group  command is also used to prepare this
84       subgroup.  The subgroup mechanism allows the user to select a subset of
85       all the band files that form an image.
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87       signaturefile=name
88           resultant signature file
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90       This  is the resultant signature file (containing the means and covari‐
91       ance matrices) for each class in the training map  that  is  associated
92       with the band files in the subgroup select (see above).
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INTERACTIVE MODE

95       If  none  of  the arguments are specified on the command line, i.gensig
96       will interactively prompt for the names of these maps and files.
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98       It should be noted that interactive mode here  only  means  interactive
99       prompting  for  maps  and files.  It does not mean visualization of the
100       signatures that result from the process.
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NOTES

103       The structure of the SIG files generated  by  i.gensig  is  as  follows
104       (ASCII file, used internally by i.maxlik):
105       Note:  the line numbers are not present in the file but have been added
106       here for explanation only:
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108       SIG file "lsat7_2000_gensig":
109        1 #
110        2 #water
111        3 4186
112        4 67.9508 48.7346 37.8915 15.3129 13.8473 12.0855
113        5 1.74334
114        6 0.439504 2.07267
115        7 0.662523 1.63501 4.21189
116        8 0.530339 2.40757 5.52857 22.433
117        9 0.561184 2.30762 5.18846 20.5364 20.4926
118       10 0.393218 1.2184 2.63628 9.61528 9.36025 5.85314
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120           ·   Line 2: text label
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122           ·   Line 3: number of points in class
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124           ·   Line 4: mean values per band of the class
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126           ·   Line 5-10: (semi)-matrix of band-band covariance
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AUTHOR

133       Michael Shapiro, U.S.Army Construction Engineering Research Laboratory
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135       Last changed: $Date: 2014-11-01 11:07:51 +0100 (Sat, 01 Nov 2014) $
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SOURCE CODE

138       Available at: i.gensig source code (history)
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140       Main  index | Imagery index | Topics index | Keywords index | Graphical
141       index | Full index
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143       © 2003-2019 GRASS Development Team, GRASS GIS 7.6.0 Reference Manual
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147GRASS 7.6.0                                                        i.gensig(1)