## 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 interactive mode provides extended functionality.

The first menu if the interactive mode 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
Parser support: Bob Covill (Tekmap, Canada)

Last changed: $Date: 2002/03/01 00:27:45 $