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 lay-
       ers in the user's current mapset.

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


       Various	GRASS  programs  depend  on one or more of the following 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 resolu-
	      tion, 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  geographic 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 (cur-
	      rently)  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 associated
	      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 ta-
	      ble 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 information 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  com-
       pressed,  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  col-
       umns  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 created 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 cannot.


       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 max-
       imum  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 neces-
       sary 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 direc-
       tory _$_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 over-
       write 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 referenced.

SSEEEE AALLSSOO
       For  more information regarding the location and function of GRASS sup-
       port 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)
