[Qgis-user] Self Intersections: Issues with Polygon Features

Nigel Berjak - General nigel at s3.co.za
Thu Jul 3 08:20:06 PDT 2025


Hi Werner

An old trick is to buffer using 0 units, which usually resolves 
self-intersections.

Cheers.

---
Regards,

Nigel Berjak
Please consider the environment before printing this email.

On 2025-07-03 16:11, Isenmann, Werner (RPF) via QGIS-User wrote:

> Hi,
> 
> some colleagues have problems with shapefiles (really...) that contain 
> polygons with self-intersections. The Vector Overlay - Clip tool, for 
> example, cannot be executed because the algorithm does not run due to 
> the self-intersection. Before executing the tool, the parameter 
> 'Invalid feature filtering' can be set to 'Skip (Ignore) Features with 
> Invalid Geometies'. The faulty polygons are then skipped, which is not 
> desirable, however.
> 
> QGIS offers various options for repairing self-intersections, for 
> example:
> 
> 1) Vector - Check Geometries plugin: however, this sometimes has very 
> long runtimes which might not be acceptable.
> 
> 2) Vector Geometry - Check Validity
> 
> a - Method QGIS: takes a very long time, or does not run through
> 
> b - Method GEOS: works correctly and quickly. However, only the first 
> error is ever found. This is not convenient for files with many errors.
> 
> Does anyone know a good solution for repairing (many) 
> self-intersections with high performance in QGIS?
> 
> Many thanks in advance,
> 
> Werner
> 
> ---
> 
> Werner Isenmann
> 
> Regierungspräsidium Freiburg
> 
> Referat 91 - Geowissenschaftliches Landesservicezentrum
> 
> Albertstraße 5
> 
> D-79104 Freiburg i. Br.
> 
> Phone: (+49) 761 208-3008
> 
> E-Mail: Werner.Isenmann at rpf.bwl.de
> 
> _______________________________________________
> QGIS-User mailing list
> QGIS-User at lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20250703/49d08179/attachment.htm>


More information about the QGIS-User mailing list