i.class(1)	       Grass User's Manual	       i.class(1)



NNAAMMEE
       ii..ccllaassss	 -  An	imagery  function that generates spectral
       signatures for an image by allowing the	user  to  outline
       regions	of interest.  The resulting signature file can be
       used as input for _i_._m_a_x_l_i_k or as a seed signature file for
       _i_._c_l_u_s_t_e_r.
       _(_G_R_A_S_S _I_m_a_g_e _P_r_o_c_e_s_s_i_n_g _P_r_o_g_r_a_m_)

SSYYNNOOPPSSIISS
       ii..ccllaassss

DDEESSCCRRIIPPTTIIOONN
       _i_._c_l_a_s_s	performs  the  first  pass  in the GRASS two-pass
       supervised image classification process; the GRASS program
       _i_._m_a_x_l_i_k  executes the second pass.  Both programs must be
       run to generate a classified map in GRASS raster format.


       _i_._c_l_a_s_s is an interactive program that allows the user  to
       outline	a region on the screen and calculate the spectral
       signature based on the cells that are within that  region.
       During  this process the user will be shown a histogram of
       the region for each image band.	The user can also display
       the  cells  of  the  image bands which fall within a user-
       specified number of standard deviations from the means  in
       the  spectral  signature.  By doing this, the user can see
       how much of the image is likely to be put into  the  class
       associated with the current signature.


       The spectral signatures that result are composed of region
       means and covariance matrices.	These  region  means  and
       covariance matrices are used in the second pass (_i_._m_a_x_l_i_k)
       to classify the image.


       Alternatively,  the  spectral  signatures   generated   by
       _i_._c_l_a_s_s can be used for seed means for the clusters in the
       _i_._c_l_u_s_t_e_r program.

UUSSEERR IINNPPUUTTSS
       The first screen in the program _i_._c_l_a_s_s asks the user  for
       the imagery _g_r_o_u_p and _s_u_b_g_r_o_u_p to be analyzed:

       LOCATION:  location     SUPERVISED  CLASSIFIER	  MAPSET:
       demo

	    Please select the group and subgroup to be analyzed

       GROUP:	    spot_______    (list  will	 show	available
       groups)
       SUBGROUP:    123________    (list will show available sub-
       groups)


	    AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
			  (OR <Ctrl-C> TO CANCEL)



       The _g_r_o_u_p should contain the imagery bands that	the  user
       wishes  to  classify.   The  _s_u_b_g_r_o_u_p  is a subset of this
       group.  The user must create a group  and  a  subgroup  by
       running	the GRASS program _i_._g_r_o_u_p before running _i_._c_l_a_s_s.
       The subgroup should contain only the image bands that  the
       user  wishes  to  classify.   Note that this subgroup must
       contain more than one band.


       After the first screen, the program asks the user for  the
       name  of the resulting signature file.  The signature file
       is both the output file for _i_._c_l_a_s_s and the required input
       file  for  the  GRASS  program  _i_._m_a_x_l_i_k.  It contains the
       region means and covariance  matrices  that  are  used  to
       classify an image in _i_._m_a_x_l_i_k.


       After entering the resulting signature file name, the user
       is asked to enter the name of a seed signature file.  This
       is optional.  A "seed" signature file is a previously cre-
       ated signature file.  Such a seed signature  file  may  be
       the  result of an earlier run of _i_._c_l_a_s_s.  The seed signa-
       ture file is copied into the new resulting signature  file
       before  any  new signatures are added by _i_._c_l_a_s_s.  In this
       way, you can collect the work from several  sessions  with
       _i_._c_l_a_s_s into one signature file.


       Next,  the  user  is asked to enter the name of the raster
       map to  be  displayed  during  the  process  of	outlining
       regions.   Typically, the user will want to enter the name
       of a color composite previously	created  by  _i_._c_o_m_p_o_s_i_t_e.
       However,  the  user  can  enter	the  name of any existing
       raster map.  This leaves the potential for using a  raster
       map  not  directly derived from the image as a backdrop on
       which the user can outline the classes of interest.


       At this point the _i_._c_l_a_s_s graphics screen will be drawn on
       the  graphics monitor and the user will be directed to use
       the mouse.  From this point on  the  user  will	primarily
       work  with the mouse, selecting options from the menus and
       outlining regions on the screen.  The only time	that  the
       user  will need to return to the text terminal is to enter
       names for the signatures created.

TTHHEE DDIISSPPLLAAYY FFRRAAMMEESS
       The display frame layout that _i_._c_l_a_s_s uses is  represented
       below for reference.

       +-----------------------+---------------------------+
       |		       |			   |
       |		       |    Map Display Frame	   |
       |		       |			   |
       |		       |			   |
       |   Histogram Display   |			   |
       |	Frame	       |			   |
       |		       |			   |
       |		       |			   |
       |		       |			   |
       |		       +---------------------------+
       |		       |			   |
       |		       |    Zoom Display Frame	   |
       |		       |			   |
       |		       |			   |
       |		       |			   |
       |		       |			   |
       |		       |			   |
       |		       |			   |
       +-----------------------+---------------------------+
       |	Menu Frame				   |
       +---------------------------------------------------+


TTHHEE MMEENNUUSS
       All  of	the  menus  in	the _i_._c_l_a_s_s program are displayed
       across the bottom of the  graphics  monitor  in	the  Menu
       Frame.	To select an option from one of these menus, sim-
       ply place the cursor over your  selection  and  press  any
       button  on  the	mouse.	Each of the menus is discussed in
       the following paragraphs.

   TThhee CCoommmmaanndd MMeennuu
       The Command Menu includes the following selections:

       _Z_o_o_m   This command allows the user to outline a rectangu-
	      lar region in either the Map or Zoom Display Frames
	      and the region is displayed, magnified, to  fit  in
	      the  Zoom  Display Frame.  A red rectangle is drawn
	      in the Map Display Frame, indicating what area  the
	      Zoom Display Frame shows.


       To  outline  the  rectangular  region simply use any mouse
       button to anchor the first corner of the border	and  then
       use any button to choose the other corner.

       _D_e_f_i_n_e _r_e_g_i_o_n
	      This  selection  takes the user to the Region Menu.
	      This menu includes the options that allow the  user
	      to  outline  a  region of interest on the displayed
	      raster map.

       _R_e_d_i_s_p_l_a_y _m_a_p
	      This selection takes  the  user  to  the	Redisplay
	      Menu.  The Redisplay Menu allows the user to redraw
	      map display frames.

       _A_n_a_l_y_z_e _r_e_g_i_o_n
	      This selection starts the process of analyzing  the
	      currently  defined  region.   A  histogram  of  the
	      defined region will be displayed for each band.  On
	      the  histogram  for  each  band, the mean, standard
	      deviation, minimum  cell	value  and  maximum  cell
	      value are marked.  The histograms are automatically
	      scaled in an attempt to fit the data into the space
	      available,  but it is possible that all of the data
	      will not fit.  In this case, as much of the data as
	      possible,  centered  around  the mean, will be dis-
	      played.  After the histograms  are  displayed,  the
	      user will be given the Signature Menu.

       _Q_u_i_t   The user should make this selection to end the ses-
	      sion with _i_._c_l_a_s_s.


   TThhee RReeggiioonn MMeennuu
       The Region Menu contains the following selections:

       _E_r_a_s_e _r_e_g_i_o_n
	      This selection erases any currently defined region.

       _D_r_a_w _r_e_g_i_o_n
	      This  selection allows the user to use the mouse to
	      draw a region on either the  Map	or  Zoom  Display
	      Frame.   An  explanation	of which mouse buttons to
	      use is displayed in the Menu Frame.  The user  does
	      not  need  to  try to complete the region boundary.
	      The last line of the region will be added when  the
	      user  selects  the  Complete  region  option on the
	      Region Menu.

       _R_e_s_t_o_r_e _l_a_s_t _r_e_g_i_o_n
	      This selection restores the last	region	that  was
	      drawn.   After  a  region  is completed, it will be
	      saved to be  restored  later.   Only  one  previous
	      region is saved.

       _C_o_m_p_l_e_t_e _r_e_g_i_o_n
	      This  selection  completes  the region that is cur-
	      rently being drawn.  As noted above, it  saves  the
	      complete	region	to  be restored later, if needed.
	      Once the user has made a complete region, it can be
	      analyzed	with  the Analyze Region selection on the
	      Command Menu.

       _D_o_n_e   Use this selection to return to the Command Menu.


TThhee RReeddiissppllaayy MMaapp MMeennuu
       The Redisplay Map Menu has the following selections, which
       are  useful to redraw the raster maps displayed in the Map
       and Zoom Display Frames.

       _M_a_p _g_e_o_g_r_a_p_h_i_c _r_e_g_i_o_n
	      This selection causes the raster	map  in  the  Map
	      Display Frame to be redrawn.

       _Z_o_o_m _r_e_g_i_o_n
	      This  selection causes the Zoom Display Frame to be
	      redrawn.

       _B_o_t_h   This selection causes both the Map and Zoom Display
	      Frames to be redrawn.

       _C_a_n_c_e_l Use  this selection if you do not want to redisplay
	      either of the above  regions.   The  user  will  be
	      returned to the Command Menu.


   TThhee AAnnaallyyzzee RReeggiioonn MMeennuu
       The Analyze Region Menu contains the Signature Menu, which
       allows the user to set the number of  standard  deviations
       and the display color, and then to display (as an overlay)
       the cells that match the signature within  the  number  of
       standard  deviations specified.	Note that once the match-
       ing cells are displayed, the Map  Display  Frame  must  be
       redisplayed  to	see  only  the original raster map again.
       The following selections are available  on  the	Signature
       Menu:

       _S_e_t _s_t_d _d_e_v_'_s
	      This selection allows the user to set the number of
	      standard deviations from the mean for  the  maximum
	      and  minimum  range.  The maximum and minimum range
	      is used when finding the	cells  that  "match"  the
	      signature.   The	user  is presented with a menu of
	      typical choices and  an  "Other"	option.   If  the
	      "Other"  option  is  selected,  enter the number of
	      standard deviations from the keyboard on	the  text
	      terminal.   Otherwise,  the selected option will be
	      used.  When the number of  standard  deviations  is
	      set,  the  histograms for each band will be redrawn
	      with the maximum and minimum range marked.


       Note that the number in parentheses on this  selection  is
       the current number of standard deviations.

       _S_e_t _c_o_l_o_r
	      This selection allows the user to set the color for
	      the display of cells that "match" the current  sig-
	      nature.  The user is presented with a menu of color
	      choices.	The color selected will be used when  the
	      Display Matches Menu selection is made.


       Note  that  the	color in parentheses on this selection is
       the current color for display.

       _D_i_s_p_l_a_y _m_a_t_c_h_e_s
	      This selection displays the cells that "match"  the
	      current  signature  in  the  current color.  A cell
	      "matches" the current signature if the  cell  value
	      in each band is between the minimum range and maxi-
	      mum range for that band defined by  the  number  of
	      standard deviations currently set.

       _D_o_n_e   When  this  selection  is  chosen, the user will be
	      asked whether or not he/she would like to save  the
	      current  signature.   If	the user answers with the
	      "Yes" selection, he/she will be asked  to  enter	a
	      description for the resultant signature file on the
	      text terminal keyboard.  The saved  signature  file
	      description  will  be  used by _i_._m_a_x_l_i_k to name the
	      category that is created from  the  current  signa-
	      ture.   After either a "No" answer or the signature
	      description is entered, the user is returned to the
	      Command Menu.


NNOOTTEESS
       _i_._c_l_a_s_s	uses the current MASK to generate the overlay for
       cells that match a signature.  As  a  result,  if  a  MASK
       already	exists it will be removed during the execution of
       this program.


       The cell values in the image bands cannot fall outside  of
       the  range  of  0 to 255.  _i_._c_l_a_s_s will report an error if
       they do.


       _i_._c_l_a_s_s, like some of the other imagery programs, does not
       use  the  standard  GRASS  display  frames.  After running
       _i_._c_l_a_s_s, you will need to create a  display  frame  (e.g.,
       using  _d_._f_r_a_m_e  or _d_._e_r_a_s_e) before you can use most of the
       GRASS display (d.) commands.


       _i_._g_r_o_u_p must be run before _i_._c_l_a_s_s to  create  an  imagery
       group  and  a  subgroup	containing  the image bands to be
       classified.


       The user can perform a supervised image classification  by
       running	_i_._c_l_a_s_s  followed by _i_._m_a_x_l_i_k.	The user can per-
       form an unsupervised classification by  running	_i_._c_l_u_s_t_e_r
       followed by _i_._m_a_x_l_i_k.


       _i_._c_l_a_s_s	is interactive and requires no command line argu-
       ments.  The user must be running a graphics display  moni-
       tor (see _d_._m_o_n) to run this program.

SSEEEE AALLSSOO
       _G_R_A_S_S _T_u_t_o_r_i_a_l_: _I_m_a_g_e _P_r_o_c_e_s_s_i_n_g


       _d_._f_r_a_m_e_,  _d_._m_o_n_,  _g_._r_e_g_i_o_n_, _i_._c_c_a_, _i_._c_l_u_s_t_e_r_, _i_._c_o_m_p_o_s_i_t_e_,
       _i_._g_r_o_u_p_, _i_._m_a_x_l_i_k_, _r_._m_a_p_c_a_l_c_, _r_._m_a_s_k

AAUUTTHHOORR
       David Satnik, Central Washington University

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_3 _$



GRASS 5.0					       i.class(1)
