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



NNAAMMEE
       _i_._g_e_n_s_i_g  - Generates statistics for _i_._m_a_x_l_i_k
	from raster map layer.
       _(_G_R_A_S_S _I_m_a_g_e_r_y _P_r_o_g_r_a_m_)

SSYYNNOOPPSSIISS
       ii..ggeennssiigg
       ii..ggeennssiigg hheellpp
       ii..ggeennssiigg ttrraaiinniinnggmmaapp==_n_a_m_e ggrroouupp==_n_a_m_e ssuubbggrroouupp==_n_a_m_e ssiiggnnaattuurreeffiillee==_n_a_m_e

DDEESSCCRRIIPPTTIIOONN
       _i_._g_e_n_s_i_g  is  a non-interactive method for generating input into _i_._m_a_x_-
       _l_i_k.  It can be used as the first pass in the GRASS two-pass  classifi-
       cation  process	(instead  of _i_._c_l_u_s_t_e_r or _i_._c_l_a_s_s).  It reads a raster
       map layer, called the training map, which has some  of  the  pixels  or
       regions already classified.  _i_._g_e_n_s_i_g will then extract spectral signa-
       tures from an image based on the classification of the  pixels  in  the
       training map and make these signatures available to _i_._m_a_x_l_i_k.


       The user would then execute the GRASS program _i_._m_a_x_l_i_k to actually cre-
       ate the final classified map.

OOPPTTIIOONNSS
   PPaarraammeetteerrss
       ttrraaiinniinnggmmaapp==_n_a_m_e
	      ground truth training map


       This map must be prepared by the user in advance. Programs like _v_._d_i_g_i_t
       or  _r_._d_i_g_i_t  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_._g_e_n_s_i_g makes no
       assumption about the origin of this map layer. It simply creates signa-
       tures  for  the classes defined in the training map for the image to be
       classified (the image is specified in other options - see below).

       ggrroouupp==_n_a_m_e
	      imagery group


       This is the name of the group that contains the band files  which  com-
       prise  the  image  to be analyzed. The _i_._g_r_o_u_p  command is used to con-
       struct groups of raster layers which comprise an image.



       ssuubbggrroouupp==_n_a_m_e
	      subgroup containing image files


       This names the subgroup within the group that selects a subset  of  the
       bands to be analyzed. The _i_._g_r_o_u_p  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.

       ssiiggnnaattuurreeffiillee==_n_a_m_e
	      resultant signature file


       This  is the resultant signature file (containing the means and covari-
       ance matrices) for each class in the training map  that	is  associated
       with the band files in the subgroup select (see above).


IINNTTEERRAACCTTIIVVEE MMOODDEE
       If  none  of  the arguments are specified on the command line, _i_._g_e_n_s_i_g
       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.

SSEEEE AALLSSOO
       _i_._g_r_o_u_p for creating groups and subgroups.


       _v_._d_i_g_i_t and _r_._d_i_g_i_t for interactively  creating the training map.


       _i_._c_l_u_s_t_e_r for unsupervised clustering as an alternative to _i_._g_e_n_s_i_g  to
       create signatures.


       _i_._c_l_a_s_s for a graphic/interactive as an alternative to _i_._g_e_n_s_i_g to cre-
       ate signatures.

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

       _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.gensig(1)
