[GRASS5] [bug #4249] (grass) v.build.polylines or v.clean: polylines created by v.build.polylines are broken back into separate lines by v.clean

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this bug's URL: http://intevation.de/rt/webrt?serial_num=4249
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Subject: v.build.polylines or v.clean: polylines created by v.build.polylines are broken back into separate lines by v.clean

Platform: GNU/Linux/x86
grass obtained from: CVS
grass binary for platform: Compiled from Sources
GRASS Version: 2006-04-05

### There is a vector consisted of 3 lines connected with nodes:

$ v.build fafkulec
Building topology ...
3 primitives registered
Building areas:  100%
0 areas built
0 isles built
Attaching islands:
Attaching centroids:  100%
Topology was built.
Number of nodes     :   3
Number of primitives:   3
Number of points    :   0
Number of lines     :   3
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0



### I need to join lines into one:

v.build.polylines input=fafkulec output=fafkulec_poly

The number of lines in the binary map is 3

Polyline 0: start line = 3
The number of polylines in the output map is 1
Building topology ...
1 primitives registered
Building areas:  100%
0 areas built
0 isles built
Attaching islands:
Attaching centroids:  100%
Topology was built.
Number of nodes     :   1
Number of primitives:   1
Number of points    :   0
Number of lines     :   1
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0



### Fine. Only one line. But once I run v.clean on it, lines become separated back. Somehow, points at which v.build.polylines joined the lines are taken for errors by the v.clean:

$ v.clean input=fafkulec_poly output=fafkulec_poly_cl type=line error=fafkulec_poly_er tool=break,rmdupl

+---------------------------------+---------------+
| Tool                            | Threshold     |
+---------------------------------+---------------+
| Break                            | 0.000000e+00 |
| Remove duplicates                | 0.000000e+00 |
+---------------------------------+---------------+
Copying vector lines ...
--------------------------------------------------
Rebuilding parts of topology ...
Building topology ...
1 primitives registered
Topology was built.
Number of nodes     :   1
Number of primitives:   1
Number of points    :   0
Number of lines     :   1
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   -
Number of isles     :   -
--------------------------------------------------
Tool: Break lines at intersections
Intersections:     2
--------------------------------------------------
Tool: Remove duplicates
Duplicates:     0
--------------------------------------------------
Rebuilding topology for output vector ...
Building topology ...
3 primitives registered
Building areas:  100%
0 areas built
0 isles built
Attaching islands:
Attaching centroids:  100%
Topology was built.
Number of nodes     :   3
Number of primitives:   3
Number of points    :   0
Number of lines     :   3
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0
--------------------------------------------------
Building topology for error vector ...
Building topology ...
2 primitives registered
Building areas:  100%
0 areas built
0 isles built
Attaching islands:
Attaching centroids:  100%
Topology was built.
Number of nodes     :   2
Number of primitives:   2
Number of points    :   2
Number of lines     :   0
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0


All the vectors mentioned above are in the location for download here:

http://www.biol.uni.wroc.pl/sieczka/udostepnione/grass/poly_clean.tar.bz2

Maciek


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