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



NNAAMMEE
       rr..sspprreeaaddppaatthh  -	Recursively  traces  the  least cost path
       backwards to cells from	which  the  cumulative	cost  was
       determined.

       (GRASS Raster Program)

SSYYNNOOPPSSIISS
       rr..sspprreeaaddppaatthh

       rr..sspprreeaaddppaatthh hheellpp

       rr..sspprreeaaddppaatthh   [[--vv]]  xx__iinnppuutt==_n_a_m_e  yy__oouuttppuutt==_n_a_m_e  [ccoooorrddii--
       nnaattee==_x_,_y_[_x_,_y_,_._._._]]oouuttppuutt==_n_a_m_e

DDEESSCCRRIIPPTTIIOONN
       _r_._s_p_r_e_a_d_p_a_t_h recursively traces the least cost path  back-
       wards  to the origin, given backlink information input map
       layers and target locations from where  paths  are  to  be
       traced.	The  backlink  information map layers record each
       cell's backlink UTM northing  (the  y_input)  and  easting
       (the x_input) coordinates from which the cell's cumulative
       cost was determined.


       The backlink inputs can be generated  from  another  GRASS
       raster  program _r_._s_p_r_e_a_d. One of the major applications of
       _r_._s_p_r_e_a_d_p_a_t_h along with _r_._s_p_r_e_a_d is to accurately find the
       least  cost  corridors  and/or  paths on a raster setting.
       More information on _r_._s_p_r_e_a_d and _r_._s_p_r_e_a_d_p_a_t_h can be found
       in Xu (1994).

FFllaaggss::
       --vv     Run verbosely.


PPaarraammeetteerrss::
       xx__iinnppuutt==_n_a_m_e
	      Name  of input raster map layer containing backlink
	      UTM easting coordinates.

       yy__iinnppuutt==_n_a_m_e
	      Name of input raster map layer containing  backlink
	      UTM northing coordinates.

       ccoooorrddiinnaattee==_x_,_y_[_,_x_,_y_,_x_,_y_, _._._._]
	      Each x,y coordinate pair gives the easting and nor-
	      thing (respectively) geographic  coordinates  of	a
	      target  point  from  which  to  backwards trace the
	      least cost path. As many points as desired  can  be
	      entered by the user.

       oouuttppuutt==_n_a_m_e
	      Name  of	raster	map layer to contain output. Also
	      can be used as the map layer of  the  input  target
	      points. If so used, the input target point map will
	      be overwritten by the output.


OOPPTTIIOONNSS
       The user can run _r_._s_p_r_e_a_d_p_a_t_h either interactively or non-
       interactively.  The  program  is  run interactively if the
       user types _r_._s_p_r_e_a_d_p_a_t_h without	specifying  flag  setting
       and  parameter  values  on the command line. In this case,
       the user will be prompted for input.


       Alternately, the user can  run  _r_._s_p_r_e_a_d_p_a_t_h  non-interac-
       tively,	by  specifying the names of raster map layers and
       desired options on the command line, using the form:


       rr..sspprreeaaddppaatthh  [[--vv]]  xx__iinnppuutt==_n_a_m_e  yy__oouuttppuutt==_n_a_m_e	 _[_c_o_o_r_d_i_-
       _n_a_t_e_=_x_,_y_[_x_,_y_,_._._._]_]oouuttppuutt==_n_a_m_e



SSEEEE AALLSSOO
       _r_._r_o_s.

RREEFFEERREENNCCEESS
       Xu,  Jianping,  1994,  Simulating  the spread of wildfires
       using a geographic information system and remote  sensing,
       Ph.  D.	Dissertation,  Rutgers University, New Brunswick,
       New Jersey.

AAUUTTHHOORR
       Jianping Xu and Richard G. Lathrop, Jr., Center for Remote
       Sensing and Spatial Analysis, Rutgers University.

NNOOTTIICCEE
       This  program  is  part	of the alpha section of the GRASS
       distribution. Unlike the  code  in  the	main  section  of
       GRASS,  the  alpha  code has not yet been fully tested for
       one release cycle.

       _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.spreadpath(1)
