1r.los(1)                      Grass User's Manual                     r.los(1)
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NAME

6       r.los  - Line-of-sight raster analysis program.
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KEYWORDS

9       raster
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SYNOPSIS

12       r.los
13       r.los help
14       r.los   input=string  output=string  coordinate=x,y   [patt_map=string]
15       [obs_elev=float]   [max_dist=float]   [--overwrite]
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17   Flags:
18       --overwrite
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20   Parameters:
21       input=string
22           Raster map containing elevation data
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24       output=string
25           Raster map name for storing results
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27       coordinate=x,y
28           Coordinate identifying the viewing location
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30       patt_map=string
31           Binary (1/0) raster map
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33       obs_elev=float
34           Height of the viewing location Default: 1.75
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36       max_dist=float
37           Max distance from  the  viewing  point  (meters)  Options:  0-99999
38           Default: 1000
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DESCRIPTION

41       r.los generates a raster map output in which the cells that are visible
42       from a user-specified observer location are marked with integer  values
43       that  represent  the  vertical angle (in degrees) required to see those
44       cells (viewshed).
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46       The program can be run either non-interactively or  interactively.   To
47       run  r.los  non-interactively,  the user must specify at least an input
48       file name, output file name, and  the  geographic  coordinates  of  the
49       user's  viewing  location on the command line; any remaining parameters
50       whose values are unspecified on the command line will be set  to  their
51       default values (see below).
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53       The  patt_map  is  the name of a binary (1/0) raster map layer in which
54       cells within the areas of interest are assigned the category value '1',
55       and all other cells are assigned the category value '0'. If this param‐
56       eter is omitted, the analysis will be  performed  for  the  whole  area
57       within  a  certain  distance of the viewing point inside the geographic
58       region boundaries.
59       Default: assign all cells that are within the max_dist and  within  the
60       user's current geographic region boundaries a value of 1.
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62       The  obs_elev= parameter defines the height of the observer (in meters)
63       above the viewing point's elevation.
64       Default: 1.75 (meters)
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66       The max_dist= parameter is the maximum distance (in  meters)  from  the
67       viewing  point  inside of which the line of sight analysis will be per‐
68       formed.  The cells outside this distance range are assigned  the  cate‐
69       gory value '0'.
70       Options: 0-99999 (stated in map units)
71       Default: 1000
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NOTES

74       For  accurate  results,  the program must be run with the resolution of
75       the geographic region set equal to the  resolution  of  the  data  (see
76       g.region).
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78       It  is advisable to use a 'pattern layer' which identifies the areas of
79       interest in which the line of sight analysis is required.  Such a  mea‐
80       sure will reduce the time taken by the program to run.
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SEE ALSO

83       g.region
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AUTHOR

86       Kewan Q. Khawaja, Intelligent Engineering Systems Laboratory, M.I.T.
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88       Last changed: $Date: 2003/05/06 13:58:46 $
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90       Full index
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94GRASS 6.2.2                                                           r.los(1)