Ubuntu Manpage: i.gensig - Generates statistics for i.maxlik from raster map.

NAME

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

KEYWORDS

       imagery,  classification,  supervised  classification,  Maximum Likelihood Classification,
       MLC, signatures

SYNOPSIS

       i.gensig
       i.gensig --help
       i.gensig  trainingmap=name  group=name  subgroup=name  signaturefile=name    [--overwrite]
       [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       trainingmap=name [required]
           Ground truth training map

       group=name [required]
           Name of input imagery group

       subgroup=name [required]
           Name of input imagery subgroup

       signaturefile=name [required]
           Name for output file containing result signatures

DESCRIPTION

       i.gensig  is  a non-interactive method for generating input into i.maxlik.  It can be used
       as the first pass in the GRASS two-pass classification process (instead  of  i.cluster  or
       g.gui.iclass).   It  reads  a raster map layer, called the training map, which has some of
       the pixels or regions already classified.  i.gensig will then extract spectral  signatures
       from an image based on the classification of the pixels in the training map and make these
       signatures available to i.maxlik.

       The user would then execute the GRASS  program  i.maxlik  to  actually  create  the  final
       classified map.

       This  module  generates  signature  files of type "sig". Use module i.signatures to manage
       generated signature files.

       All raster maps used to generate signature file can have semantic label set. Use r.support
       to  set semantic labels of each member of the imagery group.  Signatures generated for one
       scene are suitable for classification of other scenes as long  as  they  consist  of  same
       raster bands (semantic labels match).

OPTIONS

Parameters
trainingmap=name
ground truth training map

This map must be prepared by the user in advance using vector or raster digitizer. Of
course other methods could be devised by the user for creating this training map -
i.gensig makes no assumption about the origin of this map layer. It simply creates
signatures for the classes defined in the training map for the image to be classified (the
image is specified in other options - see below). The wxGUI vector digitizer can be used
for interactively creating the training map.

group=name
imagery group

This is the name of the group that contains the band files which comprise the image to be
analyzed. The i.group command is used to construct groups of raster layers which comprise
an image.

subgroup=name
subgroup containing image files

This names the subgroup within the group that selects a subset of the bands to be
analyzed. The i.group command is also used to prepare this subgroup. The subgroup
mechanism allows the user to select a subset of all the band files that form an image.

signaturefile=name
resultant signature file

This is the resultant signature file (containing the means and covariance matrices) for
each class in the training map that is associated with the band files in the subgroup
select (see above). Resultant singature file can be used with any other imagery group as
long as semantic labels match.

NOTES

       The  structure  of  the  SIG  files  generated by i.gensig is as follows (ASCII file, used
       internally by i.maxlik):
       Note: the line numbers are  not  present  in  the  file  but  have  been  added  here  for
       explanation only:

       SIG file "lsat7_2000_gensig":
        1 1
        2 #
        3 Semantic_label1
        4 #water
        5 4186
        6 67.9508 48.7346 37.8915 15.3129 13.8473 12.0855
        7 1.74334
        8 0.439504 2.07267
        9 0.662523 1.63501 4.21189
       10 0.530339 2.40757 5.52857 22.433
       11 0.561184 2.30762 5.18846 20.5364 20.4926
       12 0.393218 1.2184 2.63628 9.61528 9.36025 5.85314

           •   Line 1: version number (currently always 1)

           •   Line 2: text label

           •   Line 3: Space separated list of semantic labels

           •   Line 4: text label of class

           •   Line 5: number of points in class

           •   Line 6: mean values per band of the class

           •   Line 7-12: (semi)-matrix of band-band covariance

AUTHORS

       Michael Shapiro, U.S.Army Construction Engineering Research Laboratory
       Semantic label support: Maris Nartiss, University of Latvia

SOURCE CODE

       Available at: i.gensig source code (history)

       Accessed: Thursday Aug 01 11:31:35 2024

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       © 2003-2024 GRASS Development Team, GRASS GIS 8.4.0 Reference Manual