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 ssiiggnnaa--
       ttuurreeffiillee==_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 classification 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
       signatures 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 create 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  representa-
       tive  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 signatures 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 comprise the image to be analyzed. The _i_._g_r_o_u_p  com-
       mand  is  used  to construct 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 mech-
       anism  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  covariance	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 train-
       ing 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 create 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)
