NAME
r.los - Line-of-sight raster analysis program.
(GRASS Raster Program)
SYNOPSIS
r.los
r.los help
r.los
input=name
output=name
coordinate=x,y
[patt_map=name]
[obs_elev=value]
[max_dist=value]
DESCRIPTION
r.los generates a raster map output in which the
cells that are visible from a user-specified observer
location are marked with integer values that represent the
vertical angle (in degrees) required to see those cells (viewshed).
The program can be run either non-interactively or interactively.
To run r.los non-interactively, the user must specify at least
an input file name, output file name, and the geographic
coordinates of the user's viewing location on the command line;
any remaining parameters whose values are unspecified on the command line
will be set to their default values (see below).
Non-interactive usage format is:
-
r.los
input=name
output=name
coordinate=x,y
[patt_map=name]
[obs_elev=value]
[max_dist=value]
Alternately, the user can type simply r.los on the command line;
in this case, the program will prompt the user for parameter values
using the standard GRASS
parser.
Parameters:
- input=name
- Name of a raster map layer containing elevation data,
used as program input.
- output=name
- Name assigned to the file in which the raster program output
will be stored.
- coordinate=x,y
- Geographic coordinates (i.e., easting and northing values)
identifying the desired location of the viewing point.
- patt_map=name
- Name of a binary (1/0) raster map layer in which cells
within the areas of interest are assigned the category
value '1', and all other cells are assigned the category
value '0'. If this parameter is omitted, the analysis will
be performed for the whole area within a certain distance
of the viewing point inside the geographic region
boundaries.
Default: assign all cells that are within the
max_dist and within the user's current geographic
region boundaries a value of 1.
- obs_elev=value
- Height of the observer (in meters) above the viewing
point's elevation.
Default: 1.75 (meters)
- max_dist=value
- Maximum distance (in meters) from the viewing point
inside of which the line of sight analysis will be
performed. The cells outside this distance range are
assigned the category value '0'.
Options: 0-99999 (stated in map units)
Default: 1000
NOTES
For accurate results, the program must be run with the resolution of the
geographic region set equal to the resolution of the data
(see g.region).
It is advisable to use a 'pattern layer' which identifies
the areas of interest in which the line of sight analysis
is required. Such a measure will reduce the time taken by
the program to run.
SEE ALSO
g.region
parser
AUTHOR
Kewan Q. Khawaja, Intelligent Engineering
Systems Laboratory, M.I.T.
Last changed: $Date$