Bug report #2088

Buffer produces incorrect results

Added by jaanvajakas - almost 12 years ago. Updated almost 12 years ago.

Status:Closed
Priority:Low
Assignee:Borys Jurgiel
Category:Python plugins
Affected QGIS version: Regression?:No
Operating System:Windows Easy fix?:No
Pull Request or Patch supplied: Resolution:duplicate
Crashes QGIS or corrupts data: Copied to github as #:12148

Description

To reproduce:
1. Create a new project in QGIS.
2. Add layer kirdem2.epg4326.shp using Layers -> Add vector layer...
3. Tools -> Geoprocessing tools -> Buffer(s), set buffer distance to -0.00003, 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. asustus├╝ksus 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).

History

#1 Updated by jaanvajakas - almost 12 years ago

  • Resolution set to duplicate
  • Status changed from Open to Closed

#2 Updated by jaanvajakas - almost 12 years ago

Sorry, I somehow managed to create two tickets. The right one is
https://trac.osgeo.org/qgis/ticket/2089

Also available in: Atom PDF