NAME

i.group - An imagery function that creates and edits groups and subgroups of (raster) imagery files.
(GRASS Image Processing Program)

SYNOPSIS

i.group

DESCRIPTION

i.group allows the user to collect raster map layers in an imagery group by assigning them to user-named subgroups or other groups. This enables the user to run analyses on any combination of the raster map layers in a group. The user creates the groups and subgroups and selects the raster map layers that are to reside in them. Imagery analysis programs like i.points, i.rectify, i.ortho.rectify and others ask the user for the name of an imagery group whose data are to be analyzed. Imagery analysis programs like i.cluster and i.maxlik ask the user for the imagery group and imagery subgroup whose data are to be analyzed.

The first menu in the i.group program asks the user to select a group. If the group does not exist, the user will be asked if he or she would like to create a new group. 

This program edits imagery groups. You may add raster map
layers to, or remove such layers from, an imagery group.
You may also create new groups.
       Please enter the group to be created/modified

  GROUP: _____________ (enter 'list' for a list of groups)


    AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
                   (OR <Ctrl-C> TO EXIT)
If the word list is entered, groups that have already been created in the user's current LOCATION_NAME and MAPSET(S) will be listed. The second menu in i.group provides the user with the following options: 
     1.    Select a different group
     2.    Edit group TITLE
     3.    Include new raster (cell) files in the group
           or remove raster (cell) files from the group
     4.    Assign colors to the group
     5.    Create a new subgroup within the group

           RETURN to exit

The options are described as follows:

  1. Select a different group
    If option number 1 is chosen, the following menu is displayed: 
         Please enter the group to be created/modified

GROUP: _____________ (enter 'list' for a list of groups)


  AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
                 (OR <Ctrl-C> TO EXIT)
    If the word list is entered, groups that have already been created in the current LOCATION_NAME and MAPSET(S) will be displayed.

  2. Edit group TITLE
    If option number 2 is selected, an entry space is provided to type in the group TITLE. This TITLE is useful in identifying each group: 
         TITLE______________________________________


This option offers an opportunity to go back and change
the entry if it is not correct by asking: Look ok?
(y/n).
  3. Include new raster (cell) files in the group or remove raster (cell) files from the group
    When choosing option number 3, the following menu is displayed: 
        LOCATION: location   GROUP: spot   MAPSET: demo

If you wish to delete a file from group [spot], remove
the 'x' from in front of the file name.

                 x_    spot.1 in demo
                 x_    spot.2 in demo
                 x_    spot.3 in demo


  AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
                (OR <Ctrl-C> TO CANCEL)
    Next,a menu listing all the other raster map layers present in the current MAPSET(S) will be displayed: 
     LOCATION: location      GROUP: spot      MAPSET: demo

Please mark an 'x' by the files to be added in 
group [spot]

                     MAPSET: demo

                    x_   composite1
                    x_   spotclass1
                    __   spotclass2

  AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
                (OR <Ctrl-C> TO CANCEL)
    If more than one MAPSET is selected, menus for those mapsets will also be displayed. All raster map layers selected with an 'x' will be included in the group being updated.

    The user will then have the opportunity to check the contents of the group that was just modified: 

     Group [spot] references the following raster files

                  __________________
                 spot.1       in demo
                 spot.2       in demo
                 spot.3       in demo
                 composite1   in demo
                 spotclass1   in demo
                  __________________
                    Look ok? (y/n)
    If the user responds with the letter y then the following sentence is displayed on the screen: 
    Group [spot] updated!
    And the main menu for i.group returns.

    If the user responds n, the menu containing the group files after it was modified will be displayed and the user will be asked to place an x in front of those raster map layers that are to be removed from the group. Then, a menu listing all of the other raster map layers in the current MAPSET will be displayed again, and the user will be again asked to place an x in front of raster map layers to be included in the group. This gives the user the opportunity to correct mistakes or make changes in the choice of raster map layers to be selected in a group without exiting i.group.

  4. Assign colors to the group
    Option number 4 provides the following menu: 
    Please indicate which files to use for red, green, and
blue colors.  You may leave any color out. You may
specify more than one color per file.  However, each
color may only be specified once.  For example, to get
a full color image, specify r,g,b for 3 different
files.  To get a grey scale image, specify rgb for a
single file.

                   b__    spot.1
                   g__    spot.2
                   r__    spot.3
                   ___    composite1
                   ___    spotclass1

       <<< r,g,b can only be specified once >>>

  AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
                (OR <Ctrl-C> TO CANCEL)
    This menu allows you to select a color for each imagery band or for each file for display. Note, however, that composite images and classified images are already assigned colors during their creation.

    An opportunity to change the choice of colors is offered after escaping the menu by: 

    Look ok? (y/n)
  5. Create a new subgroup within the group
    The following menu enables the user to create a subgroup out of any combination of raster map layers in the group. Any number of subgroups may be created by repeating the option. 
        LOCATION: location                MAPSET: spot

GROUP: spot1
SUBGROUP: ___________ ('list' will show available 
subgroups)

  AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
                (OR <Ctrl-C> TO CANCEL)
    After selecting or creating a subgroup, this menu is displayed: 
        Mark an 'x' by the files to form subgroup [123]

                   x_    spot.1
                   x_    spot.2
                   x_    spot.3
                   __    composite1
                   __    spotclass1

  AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
                (OR <Ctrl-C> TO CANCEL)
    The user is then given the opportunity to check the contents of the subgroup: 
    Subgroup [123] references the following raster 
(cell) files

                  __________________
                   spot.1   in demo
                   spot.2   in demo
                   spot.3   in demo
                  __________________
                    Look ok? (y/n)
    If the user responds with the letter n, the group menu will appear again enabling the user to select raster map layers to form the subgroup.

NOTES

The i.group options are only available for imagery map layers in the current LOCATION_NAME.

Subgroup names may not contain more than 12 characters.

This program is interactive and requires no command line arguments.

SEE ALSO

GRASS Tutorial: Image Pro cessing

i.cluster
i.maxlik
i.points
i.rectify

AUTHOR

Michael Shapiro, U.S.Army Construction Engineering Research Laboratory