
NAME
r.distance - Locates the closest points between objects in two raster maps.
KEYWORDS
raster
SYNOPSIS
r.distance
r.distance help
r.distance [-loq] maps=map1,map2 [fs=string] [--verbose] [--quiet]
Flags:
- -l
- Include category labels in the output
- -o
- Report zero distance if rasters are overlapping
- -q
- Run quietly
- --verbose
- Verbose module output
- --quiet
- Quiet module output
Parameters:
- maps=map1,map2
- Maps for computing inter-class distances
- fs=string
- Output field separator
- Default: :
DESCRIPTION
Locates the closest points between "objects" in two raster maps. An
"object" is defined as all the grid cells that have the same category
number, and closest means having the shortest "straight-line" distance.
The cell centers are considered for the distance calculation (two
adjacent grid cells have the distance between their cell centers).
The output is an ascii list, one line per pair of objects
cat1:cat2:distance:east1:north1:east2:north2
Explanation:
- cat1
- Category number from map1
- cat2
- Category number from map2
- distance
- The distance in meters between "cat1" and "cat2"
- east1,north1
- The coordinates of the grid cell "cat1" which is closest to "cat2"
- east2,north2
- The coordinates of the grid cell "cat2" which is closest to "cat1"
NOTES
The output format lends itself to filtering. For example, to "see" lines
connecting each of the category pairs in two maps, filter the output using
awk and then into d.map graph:
r.distance maps=map1,map2 | \
awk -F: '{print "move",$4,$5,"\ndraw",$6,$7}' | d.graph -m
To create a site list of all the "map1" coordinates, filter the output into
awk and then into s.in.ascii:
r.distance maps=map1,map2 | \
awk -F: '{print $4,$5}' | s.in.ascii sites=name
SEE ALSO
r.buffer,
r.cost,
r.drain,
v.distance
AUTHOR
Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
Last changed: $Date: 2006-10-04 07:32:47 -0700 (Wed, 04 Oct 2006) $
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