Opened 14 years ago
Closed 13 years ago
#2089 closed bug (invalid)
Buffer produces incorrect results with multipart vectors
Reported by: | jaanvajakas | Owned by: | cfarmer |
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Priority: | major: does not work as expected | Milestone: | Version 1.6.0 |
Component: | Python plugins and bindings | Version: | Trunk |
Keywords: | Cc: | ||
Must Fix for Release: | No | Platform: | All |
Platform Version: | Awaiting user input: | no |
Description
To reproduce:
- create a new project in QGIS,
- add layer kirdem2.epg4326.shp using Layers -> Add vector layer...,
- Tools -> Geoprocessing tools -> Buffer(s), set buffer distance to -0.0003, choose output file, click OK
Expected result: an inner buffer of the polygons in platte carree distance (not real distance, as interpreting degrees as meters would be ambiguous)
Actual result: certainly not a buffer neither in platte carree distance nor in real geodetic distance nor any other projection. In some places, the buffer exceeds the original polygon border (see qgis_buffer_bug1.png); in some places, the buffer has "pixel artifacts" (qgis_buffer_bug1.png); some islands are missing altogether (qgis_buffer_bug2.png).
The input data kirdem2.epg4326.shp is part of the publicly available dataset '01.09.2009a. asustusüksus SHP' (zip - 13,65 MB, 6.11.2009 ) on http://www.maaamet.ee/index.php?lang_id=1&page_id=272&menu_id=0 (I cut a small part out and converted to EPSG:4326 using QGIS).
Attachments (3)
Change History (7)
by , 14 years ago
Attachment: | kirdem2.epsg4326.zip added |
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by , 14 years ago
Attachment: | qgis_buffer_bug1.png added |
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by , 14 years ago
Attachment: | qgis_buffer_bug2.png added |
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comment:1 by , 14 years ago
Owner: | changed from | to
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comment:2 by , 14 years ago
Milestone: | → Version 1.4.0 |
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Platform: | Windows → All |
Priority: | critical: causes crash or data corruption → major: does not work as expected |
Summary: | Buffer produces incorrect results → Buffer produces incorrect results with multipart vectors |
Version: | 1.3.0 → HEAD |
If you transform your vector from multipart to singleparts the buffer results ok.
This may be a simple workaround or it may be simply necessary, I'm not sure how buffer tools is supposed to work with multipart vectors.
Carson?
comment:3 by , 14 years ago
Milestone: | Version 1.5.0 → Version 1.6.0 |
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awaiting Carson reply, I'll push this to 1.6 as in any case there is a workaround
comment:4 by , 13 years ago
Resolution: | → invalid |
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Status: | new → closed |
Tested using r14367.
I am unable to reproduce this error. Looking at the areas described in this ticket, results appear to be as expected. I suspect this was a GEOS error, but appears to now have been fixed (GEOS version?). Please test and confirm if this now works.
I am going to close this as "invalid" because this is now a relatively old ticket, and appears to now be invalid, however, if it is still a problem, please reopen this ticket.
Carson
the input dataset