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



NNAAMMEE
       rr..ggrrooww	-  Generates  an output raster map layer with contiguous areas
       grown by one cell (pixel).
       _(_G_R_A_S_S _R_a_s_t_e_r _P_r_o_g_r_a_m_)

SSYYNNOOPPSSIISS
       rr..ggrrooww
       rr..ggrrooww hheellpp
       rr..ggrrooww [--bbqq] iinnppuutt==_n_a_m_e oouuttppuutt==_n_a_m_e

DDEESSCCRRIIPPTTIIOONN
       _r_._g_r_o_w adds one cell around the perimeters of all areas in a user-spec-
       ified raster map layer and stores the output in a new raster map layer.


       An area consists of any contiguous clump of cells with  non-zero  cate-
       gory  values.  No distinction is made between differing category values
       within an area. Rather, a border is grown around the  outside  of  each
       entire contiguous set of non-zero cells.


       The  oouuttppuutt  raster map layer will not go outside the boundaries set in
       the current geographic region.  Thus, if a contiguous area in the iinnppuutt
       raster  map  layer  extends  to	the geographic edge of the current map
       layer, no new border cells can be added to that side of the area.


       Growth around a rectangular area in the iinnppuutt  raster  map  layer  will
       occur  straight out from each edge, but not diagonally from the corners
       of the rectangle. Thus, the "grown"  border  area  will	contain  lines
       along the edge of the original rectangle, but the corners of the border
       will not be squared off.  Instead, the lines of	the  border  which  go
       along  each  side of the original rectangle will touch only at the cor-
       ners of the cells at the end of each line.

OOPPTTIIOONNSS
       The user can run _r_._g_r_o_w either interactively or non-interactively.  The
       program	is run interactively if the user types rr..ggrrooww without specify-
       ing flag settings and parameter values on the command  line.   In  this
       case, the user will be prompted for input.


       Alternately,  the  user can run _r_._g_r_o_w non-interactively, by specifying
       the names of an iinnppuutt and oouuttppuutt map layer, and including  any  desired
       flags, on the command line.



   FFllaaggss::
       --bb     Output  a  binary raster map layer having only zero-one category
	      values, regardless of the  category  values  in  the  iinnppuutt  map
	      layer.   In  this case, all cells with a non-zero category value
	      in the iinnppuutt map layer are assigned to category 1 in the	oouuttppuutt
	      map  layer.  If the -b flag is not used, these cells will retain
	      their original non-zero category values.	In  either  case,  all
	      cells  whose category value is changed from 0 during the growing
	      process are assigned a category value of 1 in the oouuttppuutt map.

       --qq     Run quietly, supressing printing of  information	about  program
	      progress to standard output.




   PPaarraammeetteerrss::
       iinnppuutt==_n_a_m_e
	      Name  of	an  existing  raster  map  layer in the user's current
	      mapset search path containing areas to be "grown".

       oouuttppuutt==_n_a_m_e
	      Name of the new raster map  layer  to  contain  program  output.
	      This map will be binary if the user sets the -b flag. Otherwise,
	      iinnppuutt map cells having  non-zero	category  values  will	retain
	      their  original  values.	In either case, all cells whose values
	      changed during growth will be assigned category value 1  in  the
	      oouuttppuutt map.


NNOOTTEESS
       The _r_._g_r_o_w command can be used to represent the boundary of one or more
       areas. In this case, the zero-one (binary) output option should NOT  be
       used.  Then  the  iinnppuutt map layer can be subtracted from the oouuttppuutt map
       layer using the _r_._m_a_p_c_a_l_c command.  All original non-zero category val-
       ues  will  be  subtracted  out,	leaving  the boundary areas only. This
       resulting zero-one boundary  depiction  can  be	displayed  over  other
       related raster map layers using the overlay option of _d_._r_a_s_t.


       If  the resolution of the current geographic region does not agree with
       the resolution of the input raster map layer, unintended resampling  of
       the  original raster map layer may occur.  The user should be sure that
       the current geographic region is set properly.

SSEEEE AALLSSOO
       _d_._r_a_s_t

       _g_._r_e_g_i_o_n

       _r_._m_a_p_c_a_l_c

       _r_._p_o_l_y

AAUUTTHHOORR
       Marjorie Larson, 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.grow(1)
