I want to take ST_Difference or ST_Intersection to take the difference between two polygons.

SELECT a.id, a.geom, st_difference(a.geom, b.geom)
FROM liechtenstein.flaechen_norden a, liechtenstein.naturschutzgebiet b

From geometry a I want only these areas which are not in geometry b. But my code - whether ST_Difference or ST_Intersection - doesnt work, I get this error:

FEHLER:  lwgeom_difference: GEOS Error: TopologyException: Input geom 0 is invalid: Ring Self-intersection at or near point 505930 5252800 at 505930 5252800

I think the problem is that there are many polgons which have a hole in themselfes. How do I include these polygons so that I get the difference?

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.