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 backwards to the
       origin, given backlink information input map layers  and  target  loca-
       tions  from  where paths are to be traced. The backlink information map
       layers record each cell's backlink UTM northing (the y_input) and east-
       ing (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 northing (respec-
	      tively)  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- interac-
       tively. 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-interactively, by speci-
       fying 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 geo-
       graphic 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)
