r.distance1grass
Locates the closest points between objects in two raster maps.
Usage
r.distance
r.distance --help
r.distance [-lon]
map=name1,name2
[,name1,name2, ...]
[separator=character]
[sort=string]
[--help]
[--verbose]
[--quiet]
[--ui]
Keywords
raster, distance
Overview
r.distance 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, in the following form:
cat1:cat2:distance:east1:north1:east2:north2
|
Category number from map1 |
|---|---|
|
Category number from map2 |
|
The distance in meters between "cat1" and "cat2" |
|
The coordinates of the grid cell "cat1" which is closest to "cat2" |
|
The coordinates of the grid cell "cat2" which is closest to "cat1" |
Flags
-l The -l flag outputs the category labels of the matched raster objects at the beginning of the line, if they exist.
-o The -o flag reports zero distance if the input rasters are overlapping.
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.graph:
r.distance map=map1,map2 | \awk -F: ’{print "move",$4,$5,"\ndraw",$6,$7}’ | d.graph -m
To create a vector map of all the "map1" coordinates, filter the output into awk and then into v.in.ascii:
r.distance map=map1,map2 | \awk -F: ’{print $4,$5}’ | v.in.ascii format=point output=name separator=space
Source code
Available at: r.distance source code (history)
Accessed: Monday Feb 24 17:50:36 2025
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© 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual
Releases
10 releases since Debian 4.0 (Etch); the text changed 9 times.