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r.spreadpath(1)		    GRASS GIS User's Manual	       r.spreadpath(1)

NAME
       r.spreadpath   -	 Recursively  traces  the least	cost path backwards to
       cells from which	the cumulative cost was	determined.

KEYWORDS
       raster, fire, cumulative	costs

SYNOPSIS
       r.spreadpath
       r.spreadpath --help
       r.spreadpath	   x_input=name		y_input=name	      [coordi-
       nates=east,north[,east,north,...]]	output=name	 [--overwrite]
       [--help]	 [--verbose]  [--quiet]	 [--ui]

   Flags:
       --overwrite
	   Allow output	files to overwrite existing files

       --help
	   Print usage summary

       --verbose
	   Verbose module output

       --quiet
	   Quiet module	output

       --ui
	   Force launching GUI dialog

   Parameters:
       x_input=nameA [required]
	   Name	of raster map containing back-path easting information

       y_input=nameA [required]
	   Name	of raster map containing back-path northing information

       coordinates=east,north[,east,north,...]
	   The map E and N grid	coordinates of starting	points

       output=nameA [required]
	   Name	for output raster map

DESCRIPTION
       r.spreadpath is part of the wildfire simulation toolset.	 Preparational
       steps for the fire simulation are the calculation of the	rate of	spread
       (ROS) with r.ros, and the creating of spread map	with r.spread.	 Even-
       tually, the fire	path(s)	based on starting point(s) are calculated with
       r.spreadpath.

       r.spreadpath 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.spread. One of	the major  applications	 of  r.spreadpath  along  with
       r.spread	is to accurately find the least	cost corridors and/or paths on
       a raster	setting. More information on r.spread and r.spreadpath can  be
       found in	Xu (1994).

Parameters:
       x_input=name
	   Name	 of input raster map layer containing backlink UTM easting co-
	   ordinates.

       y_input=name
	   Name	of input raster	map layer containing backlink UTM northing co-
	   ordinates.

       coordinates =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.

       output=name
	   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.

REFERENCES
	   o   Xu, Jianping, 1994, Simulating the spread of wildfires using  a
	       geographic  information	system and remote sensing, Ph. D. Dis-
	       sertation, Rutgers University, New Brunswick, New Jersey	(ref).

SEE ALSO
	r.spread, r.ros	Sample data download:  firedemo.sh  (run  this	script
       within the "Fire	simulation data	set" location.

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

SOURCE CODE
       Available at: r.spreadpath source code (history)

       Main index | Raster index | Topics index	| Keywords index  |  Graphical
       index | Full index

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.4 Reference	Manual

GRASS 7.8.4						       r.spreadpath(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | Parameters: | REFERENCES | SEE ALSO | AUTHOR | SOURCE CODE

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