r.support(1)	       Grass User's Manual	     r.support(1)



NNAAMMEE
       rr..ssuuppppoorrtt   -  Allows  the  user  to  create and/or modify
       raster map layer support files.
       _(_G_R_A_S_S _R_a_s_t_e_r _P_r_o_g_r_a_m_)

SSYYNNOOPPSSIISS
       rr..ssuuppppoorrtt [--rr] mmaapp==_n_a_m_e

OOPPTTIIOONNSS
   FFllaagg::
       --rr Update the stats (histogram, range)


DDEESSCCRRIIPPTTIIOONN
       The GRASS program _r_._s_u_p_p_o_r_t  allows  the  user  to  create
       and/or  modify  raster map layer support files.	It may be
       run only on  raster  map  layers  in  the  user's  current
       mapset.

	Most  options  have to be used interactively, so the user
       runs the program by typing rr..ssuuppppoorrtt, and will be  queried
       for inputs.


       Various	GRASS  programs depend on one or more of the fol-
       lowing GRASS _s_u_p_p_o_r_t files:

       cceellllhhdd The cell header  file  contains  information  on	a
	      map's  projection,  zone,  regional boundaries, row
	      and column totals, cell resolution, storage format,
	      and  compression.   It describes where and how this
	      map's raster (cell) data fits in with reference  to
	      other  raster  map  layers'  data.  Without it, the
	      raster map layer could not be displayed or analyzed
	      properly.  Using _r_._s_u_p_p_o_r_t, the user can change the
	      # of columns, # of bytes per cell, and default geo-
	      graphic  region  settings.   Generally, users would
	      not change this information.  Cell header files are
	      stored  under the _c_e_l_l_h_d directory under the user's
	      current mapset.

       ssttaattss  Raster map layer statistics are saved in	the  form
	      of  a  histogram	and  range of the category values
	      which occur in the map layer.  Statistics files are
	      stored in subdirectories of the _c_e_l_l___m_i_s_c directory
	      under the user's current mapset.	 This  option  is
	      (currently)  the	only  option which can be used on
	      command line (-r flag).

       ccaattss   A category file associates each category	value  in
	      the  raster  map	layer with a category description
	      (label).	The user may add  or  edit  the  category
	      descriptions,  alter  the number of categories, and
	      add or alter the map's TITLE.  Category files asso-
	      ciated  with raster map layers are stored under the
	      _c_a_t_s directory in the user's current mapset.

       ccoollrr   A color file associates each category value in  the
	      raster  map  layer  with a color.  Using _r_._s_u_p_p_o_r_t,
	      the user may assign one of eight color table  types
	      to the raster map layer.	Map color table files are
	      stored under the _c_o_l_r and _c_o_l_r_2  directories  under
	      the user's current mapset.

       hhiisstt   Historical  information  about the raster map layer
	      is stored in a history file.  The user may  add  or
	      edit  the  raster  map's	TITLE,	data  type,  data
	      source, data  description,  and  include	comments.
	      (Note  that the specification of map data type here
	      is somewhat archaic, and should always  be  set  to
	      _r_a_s_t_e_r.)	 Map  history  files are stored under the
	      _h_i_s_t directory under the user's current mapset.


NNOOTTEESS
       The _r_._s_u_p_p_o_r_t program attempts to verify that the informa-
       tion  in  the  cell  header is reasonable. The data format
       specified in the header is verified against the raster map
       layer  itself. This includes checking that files which the
       header indicates are _c_o_m_p_r_e_s_s_e_d are really compressed, and
       that  the  number  of  rows  and  columns specified in the
       header correspond to the actual file size.


       The _r_._s_u_p_p_o_r_t program can also be used  to  determine  the
       number  of columns and rows of data in a raster map layer,
       in the event that no cell header is  available.	 This  is
       useful,	for example, for importing raster map layers cre-
       ated by software other than GRASS.


       If the file is not compressed, the file size should be the
       product of the number of rows and columns.  If the file is
       compressed, this test cannot be performed since	the  file
       size  will  bear no relation to the product. The number of
       rows can still be verified, but the number of columns can-
       not.


       To  compute  or correct the _s_t_a_t_s, the cell header must be
       correct, since the raster map layer is read  to	determine
       the stats.


       If  a  new  _c_a_t_s  or _c_o_l_r (or _c_o_l_r_2) file is required, the
       _s_t_a_t_s must be correct.


       The user is allowed to change  the  number  of  categories
       specified  in  the category file. This should oonnllyy be done
       if the user knows that the maximum category value  in  the
       raster  map layer is different than that which is recorded
       in the category file.  Changing the category value in  the
       _c_a_t_s  file allows the user to add more category labels, or
       to remove labels. It does NOT change the  category  values
       in the raster map layer itself.


       The color file is unique among GRASS support files.  While
       it is necessary to protect a  user's  original  data  from
       being modified by users working under other mapsets, these
       users need to be able to create color tables for maps that
       are  stored  under  mapsets  other  than their own.  Color
       table files meet both these objectives.


       Color table files get stored in one  of	two  directories,
       both  under  the  user's  current  mapset. The color files
       created by a user for raster maps stored under that user's
       current	mapset get stored in the directory _$_L_O_C_A_T_I_O_N_/_c_o_l_r
       and cannot be modified or removed  by  other  users.   The
       color  table  files  that  the  user  modifies/creates for
       raster map layers _n_o_t  stored  under  the  user's  current
       mapset  get  stored  in	a  _s_e_c_o_n_d_a_r_y _c_o_l_o_r file under the
       user's mapset.  This secondary color table is stored under
       $LOCATION/colr2/  where	 is  the name of the mapset under
       which the raster map data  are  stored.	 In  versions  of
       GRASS  prior  to  3.0,  this  was  also the case for color
       tables in the user's own mapset. Now, however, if  a  user
       modifies  a color table associated with a raster map layer
       in his own current mapset, these changes will be  made  to
       the  user's  original  color  file (i.e., the user's color
       changes will overwrite whatever previous color table  file
       existed	for  this  map	under  the  user's $LOCATION/colr
       directory).  No secondary  color  files	are  created  for
       raster map layers stored in the user's own mapset.

WWAARRNNIINNGG
       In  order to modify the _c_e_l_l _h_e_a_d_e_r, the raster (cell) map
       layer under consideration must _n_o_t be a _r_e_c_l_a_s_s file. This
       is  because  the  _r_e_c_l_a_s_s  file's  header does not contain
       positional information, but rather a reference to  another
       raster  map  layer.  Thus it shares a cell header with the
       referenced raster map layer.  In order to change the  cell
       header, _r_._s_u_p_p_o_r_t must be run on the true raster file ref-
       erenced.

SSEEEE AALLSSOO
       For more information regarding the location  and  function
       of  GRASS  support  files,  consult the GGRRAASSSS PPrrooggrraammmmeerr''ss
       MMaannuuaall chapter on "GRASS Database Structure"


       _d_._c_o_l_o_r_s

       _r_._c_o_l_o_r_s

       _r_._r_e_c_l_a_s_s

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

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_4 _$



GRASS 5.0					     r.support(1)
