this bug's URL: http://intevation.de/rt/webrt?serial_num=4247
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Subject: v.build.polylines: fails to build a polyline out of a closed boundary
Platform: GNU/Linux/x86
grass obtained from: CVS
grass binary for platform: Compiled from Sources
GRASS Version: 2006-04-05
If v.build.polylines in run on a topologicaly clean, self-closed boundary, the output will be an "incorrect bondary", twice that long as the input.
See screenshots from v.digit:
input:
http://www.biol.uni.wroc.pl/sieczka/udostepnione/grass/poly/parcel.png
v.build.polylines output "incorrect boundary":
http://www.biol.uni.wroc.pl/sieczka/udostepnione/grass/poly/parcel_poly.png
after editing the output the problem becomes visible:
http://www.biol.uni.wroc.pl/sieczka/udostepnione/grass/poly/parcel_poly_edited.png
Details:
### See that the input is clean:
$ v.build parcel
Building topology ...
1 primitives registered
Building areas: 100%
1 areas built
1 isles built
Attaching islands: 100%
Attaching centroids: 100%
Topology was built.
Number of nodes : 1
Number of primitives: 1
Number of points : 0
Number of lines : 0
Number of boundaries: 1
Number of centroids : 0
Number of areas : 1
Number of isles : 1
Number of areas without centroid : 1
### But after processing with the v.build.polylines it is not (an incorrect
### boundary is created):
$ v.build.polylines input=parcel output=parcel_poly
reating new map parcel_poly
The number of lines in the binary map is 1
Polyline 0: start line = 1
The number of polylines in the output map is 1
Building topology ...
Registering lines:
1 primitives registered
Building areas:
0 areas built
0 isles built
Attaching islands:
Attaching centroids:
Topology was built.
Number of nodes : 1
Number of primitives: 1
Number of points : 0
Number of lines : 0
Number of boundaries: 1
Number of centroids : 0
Number of areas : 0
Number of isles : 0
Number of incorrect boundaries : 1
Grass location with forementioned vectors:
http://www.biol.uni.wroc.pl/sieczka/udostepnione/grass/poly/poly.tar.bz2
Maciek
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