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     [coordinates=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=name [required]
           Name of raster map containing back-path easting information

       y_input=name [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=name [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.   Eventually, 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 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.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 coordinates.

       y_input=name
           Name of input raster map layer containing backlink UTM northing coordinates.

       coordinates =x,y[,x,y,x,y, ...]
           Each  x,y  coordinate  pair  gives  the easting and northing (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.

       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

           •   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 (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.

       Last changed: $Date: 2014-11-28 16:43:22 +0100 (Fri, 28 Nov 2014) $

SOURCE CODE

       Available at: r.spreadpath source code (history)

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       © 2003-2018 GRASS Development Team, GRASS GIS 7.4.0 Reference Manual