NAME
r.spreadpath - Recursively traces the least cost path backwards to cells
from which the cumulative cost was determined. (GRASS Raster Program)
SYNOPSIS
r.spreadpath
r.spreadpath help
r.spreadpath [-v] x_input=name y_output=name [coordinate=x,y[x,y,...]]
output=name
DESCRIPTION
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).
Flags:
-v Run verbosely.
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.
coordinate=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.
OPTIONS
The user can run r.spreadpath either interactively or non- interactively.
The program is run interactively if the user types r.spreadpath 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.spreadpath non- interactively,
by specifying the names of raster map layers and desired options on the
command line, using the form:
r.spreadpath [-v] x_input=name y_output=name [coordinate=x,y[x,y,...]]
output=name
SEE ALSO
r.spread, r.ros.
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.
AUTHOR
Jianping Xu and Richard G. Lathrop, Jr., Center for Remote Sensing and
Spatial Analysis, Rutgers University.
NOTICE
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.