Hi Simon!
Seems like a common problem that GIS should handle easy, but it is perhaps not
that easy. I had a similar problem that ended up in below. I have my data in
Postgres + PostGIS so it is handled by the database in in a view. The code
disassembles the polygons in the rings, union the rings and then build polygons
again from the lines. Then I do a join with the original data (in this case not
exactly) based on location on the centerpoint. In your case I would do a
suitable group by and concatenate the attributes. Hope this helps even it is
not QGIS.
WITH orings AS (
SELECT st_exteriorring((st_dumprings((st_dump(omr.geom)).geom)).geom)
AS geom
FROM qdp2.omr
), oboundaries AS (
SELECT st_union(orings.geom) AS geom
FROM orings
), opoly AS (
SELECT (st_dump(st_polygonize(oboundaries.geom))).geom AS geom
FROM oboundaries
)
SELECT row_number() OVER () AS id,
p.namn,
'delområde'::text AS delomr,
p.plan_uuid,
p.status,
p.publicerad,
op.geom
FROM opoly op,
qdp2.plan_omr po,
qdp2.plan p
WHERE st_contains(po.geom, st_pointonsurface(op.geom)) AND po.plan_uuid =
p.plan_uuid
Med vänliga hälsningar
Karl-Magnus Jönsson
Från: QGIS-User <[email protected]> För Simon Dietmann via
QGIS-User
Skickat: den 17 februari 2026 15:01
Till: qgis-user <[email protected]>
Ämne: [Qgis-user] aggregate polygon overlay
Dear list,
I am trying to solve the following problem:
I have one polygon layer with many polygons that are in many cases overlapping
and with different attribute valus, e.g. a, b, c:
[cid:[email protected]]
My goal is to generate a polygon layer with polygons for every overlap
constellation containing a concat string of those attributes, in this example
seven polygons with the attributes a, b, c, ab, bc, ac, abc.
I started with a union of my original layer, the result is a layer with 12
polygons where overlapping areas of the original polygons result in overlapping
intersections containing one of the original attributes each, for example in
the middle, there are 3 polygons, one with a, one with b and one with c.
How is it possible to summarize those overlapping polygons into one polygon
each with all the attributes, given that there is a large number of polygons
and different attributes?
Thank you for any hints,
regards
Simon
i.A. Simon Dietmann
Projektleiter | Geograph
[cid:[email protected]]
PGNU Planungsgesellschaft Natur & Umwelt mbH
Amtsgericht Frankfurt am Main, HRB 111938;
Geschäftsführer: Dr. Benjamin Hill, Dorit Thurm, Sebastian Braun
Hamburger Allee 45 +++ 60486 Frankfurt am Main
Durchwahl: +49 69 952964-32 +++ Fax: +49 69 952964-99
E-Mail: [email protected]<mailto:[email protected]> +++ Web:
www.pgnu.de<http://www.pgnu.de>
> Diese E-Mail könnte vertrauliche und/oder rechtlich geschützte Informationen
> enthalten. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail
> irrtümlich erhalten haben, informieren Sie bitte sofort den Absender und
> vernichten Sie diese Mail. Das unerlaubte Kopieren sowie die unbefugte
> Weitergabe dieser Mail sind nicht gestattet.
> This e-mail may contain confidential and/or privileged information. If you
> are not the intended recipient (or have received this e-mail in error) please
> notify the sender immediately and destroy this e-mail. Any unauthorised
> copying, disclosure or distribution of the material in this e-mail is
> strictly forbidden.
_______________________________________________
QGIS-User mailing list
[email protected]
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
