NAME¶
i.gensig - Generates statistics for i.maxlik from raster map.
KEYWORDS¶
imagery, classification, supervised, MLC
SYNOPSIS¶
i.gensig
i.gensig help
i.gensig trainingmap=
name group=
name
subgroup=
name signaturefile=
string
[--
verbose] [--
quiet]
Parameters:¶
- trainingmap=name
-
Ground truth training map
- group=name
-
Name of input imagery group
- subgroup=name
-
Name of input imagery subgroup
- signaturefile=string
-
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
i.class). 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.
OPTIONS¶
Parameters¶
- trainingmap=name
-
ground truth training map
This map must be prepared by the user in advance. Programs like
v.digit
or
r.digit can be used to define representative areas of the
classes the user defines to be in the image. 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).
- 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).
INTERACTIVE MODE¶
If none of the arguments are specified on the command line,
i.gensig will
interactively prompt for the names of these maps and files.
It should be noted that interactive mode here only means interactive prompting
for maps and files. It does not mean visualization of the signatures that
result from the process.
SEE ALSO¶
i.group for creating groups and subgroups.
v.digit and
r.digit for interactively creating the training map.
i.cluster for unsupervised clustering as an alternative to
i.gensig to create signatures.
i.class for a graphic/interactive as an alternative to
i.gensig to
create signatures.
AUTHOR¶
Michael Shapiro, U.S.Army Construction Engineering Research Laboratory
Last changed: $Date: 2011-11-08 12:29:50 +0100 (Tue, 08 Nov 2011) $
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© 2003-2011 GRASS Development Team