Opened 10 years ago
Last modified 6 years ago
#2531 new defect
v.parallel/v.segment: strange output
Reported by: | hellik | Owned by: | |
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Priority: | critical | Milestone: | 7.6.2 |
Component: | Vector | Version: | svn-trunk |
Keywords: | v.parallel, v.segment | Cc: | |
CPU: | Unspecified | Platform: | MSWindows Vista |
Description
tested in the nc sample data set
v.extract input=streams@PERMANENT cats=83348 output=streams_oneline v.parallel --verbose input=streams_oneline@user1 output=streams_oneline_parallel_test distance=100 side=both
see attached result; is this correct?
Attachments (3)
Change History (21)
by , 10 years ago
Attachment: | vparallel.png added |
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comment:1 by , 10 years ago
follow-up: 4 comment:2 by , 10 years ago
Keywords: | v.parallel added; parallel removed |
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IMHO this ticket is a duplicate of #90
follow-up: 5 comment:3 by , 10 years ago
Milestone: | 7.1.0 → 7.0.0 |
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Priority: | major → blocker |
comment:4 by , 10 years ago
follow-up: 6 comment:5 by , 10 years ago
Replying to hellik:
I wonder why it's blocker? I would say it's critical, but not the blocker.
comment:6 by , 10 years ago
Replying to martinl:
Replying to hellik:
I wonder why it's blocker? I would say it's critical, but not the blocker.
IMHO create parallel vector lines is a basic GIS function which should work in a release of a new GRASS GIS generation. additionally it's still an longstanding issue in g6 (see #90).
please feel free to downgrade.
follow-up: 8 comment:7 by , 10 years ago
Priority: | blocker → critical |
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It does not impact the overall GRASS functionality, hence downgrading.
We may also consider to move it to Addons... I am not sure how important v.parallel is.
by , 10 years ago
Attachment: | vsegment.png added |
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comment:8 by , 10 years ago
Replying to neteler:
I am not sure how important v.parallel is.
IMHO creating parallel vector lines is a core functionality of a GIS vector engine.
We may also consider to move it to Addons...
then, also v.segment should be moved to addons (see screenshot), as also this module is affected by the underlying function.
my 0.02c
comment:9 by , 10 years ago
Keywords: | v.segment added |
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comment:10 by , 10 years ago
Summary: | v.parallel: strange output → v.parallel/v.segment: strange output |
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comment:11 by , 10 years ago
In Vect_line_parallel2 in lib/vector/Vlib/buffer2.c, a call to clean_parallel is commented out. clean_parallel exists in buffer.c, not in buffer2.c. Maybe this might be a path to a solution.
What seems to be the issue (AFAIU) is that the length of the parallel line segments is longer than that of the original line segments, as if the lines as projected outward. This seems to be what leads to the loops. Don't know why such a projection is done... I'll attach a screenshot to show what I mean.
Have you checked out the -b flag ? And possibly tried to generalize the line before creating using v.parallel. Both might actually give you what you are looking for ?
by , 10 years ago
Attachment: | example_parallel_lines_longer_than_original.png added |
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comment:12 by , 9 years ago
Milestone: | 7.0.0 → 7.0.3 |
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comment:15 by , 9 years ago
Milestone: | 7.0.4 → 7.0.5 |
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comment:16 by , 8 years ago
Milestone: | 7.0.5 → 7.0.6 |
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comment:17 by , 7 years ago
Milestone: | 7.0.6 → 7.0.7 |
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comment:18 by , 6 years ago
Milestone: | 7.0.7 → 7.6.2 |
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Replying to hellik:
tested with