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 layer.
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KEYWORDS

9       imagery
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SYNOPSIS

12       i.gensig
13       i.gensig help
14       i.gensig  trainingmap=string  group=string  subgroup=string  signature‐
15       file=string  [--verbose]  [--quiet]
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17   Parameters:
18       trainingmap=string
19           Ground truth training map
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21       group=string
22           Imagery group
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24       subgroup=string
25           Subgroup containing image files
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27       signaturefile=string
28           Resultant signature file
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DESCRIPTION

31       i.gensig is a non-interactive method for generating input  into  i.max‐
32       lik.   It can be used as the first pass in the GRASS two-pass classifi‐
33       cation process (instead of i.cluster or i.class).  It  reads  a  raster
34       map  layer,  called  the  training map, which has some of the pixels or
35       regions already classified.  i.gensig will then extract spectral signa‐
36       tures  from  an  image based on the classification of the pixels in the
37       training map and make these signatures available to i.maxlik.
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39       The user would then execute the GRASS program i.maxlik to actually cre‐
40       ate the final classified map.
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OPTIONS

43   Parameters
44       trainingmap=name
45              ground truth training map
46
47       This map must be prepared by the user in advance. Programs like v.digit
48       or r.digit can be used to define representative areas  of  the  classes
49       the  user defines to be in the image.  Of course other methods could be
50       devised by the user for creating this training map - i.gensig makes  no
51       assumption about the origin of this map layer. It simply creates signa‐
52       tures for the classes defined in the training map for the image  to  be
53       classified (the image is specified in other options - see below).
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55       group=name
56              imagery group
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58       This  is  the name of the group that contains the band files which com‐
59       prise the image to be analyzed. The i.group  command is  used  to  con‐
60       struct groups of raster layers which comprise an image.
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62       subgroup=name
63              subgroup containing image files
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65       This  names  the subgroup within the group that selects a subset of the
66       bands to be analyzed. The i.group  command is also used to prepare this
67       subgroup.  The subgroup mechanism allows the user to select a subset of
68       all the band files that form an image.
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70       signaturefile=name
71              resultant signature file
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73       This is the resultant signature file (containing the means and  covari‐
74       ance  matrices)  for  each class in the training map that is associated
75       with the band files in the subgroup select (see above).
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INTERACTIVE MODE

78       If none of the arguments are specified on the  command  line,  i.gensig
79       will interactively prompt for the names of these maps and files.
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81       It  should  be  noted that interactive mode here only means interactive
82       prompting for maps and files.  It does not mean  visualization  of  the
83       signatures that result from the process.
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SEE ALSO

86       i.group for creating groups and subgroups.
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88       v.digit and r.digit for interactively  creating the training map.
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90       i.cluster  for unsupervised clustering as an alternative to i.gensig to
91       create signatures.
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93       i.class for a graphic/interactive as an alternative to i.gensig to cre‐
94       ate signatures.
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AUTHOR

97       Michael Shapiro, U.S.Army Construction Engineering Research Laboratory
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99       Last changed: $Date: 2003-04-17 16:51:33 +0200 (Thu, 17 Apr 2003) $
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101       Full index
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103       © 2003-2008 GRASS Development Team
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107GRASS 6.3.0                                                        i.gensig(1)