I am using QGIS 3.8 and I am using a layer from OSM of Tokyo city. The layer is consisted from many polygons and I have tried to merge it but I got error. This is how the original layer was look like: enter image description here

This is the parts I manage to merge: enter image description here

When I have checked the geometry validity no error appeard on the problematic areas, beside this one that appeard on area that I manage to merge. I have tried to check but couldn't find any visible error:

enter image description here

I really don't know how to fix it and how to merge the "green layers" with the pink ones. I have seen previous messages in this forum but they were using scripts.

any idea ?

  • What error did you get? Commented Nov 12, 2019 at 11:10
  • Holes lies outside shell
    – ReutKeller
    Commented Nov 12, 2019 at 12:51
  • Which tool are you using? Try to use Dissolve (Native and from GDAL) and Polygon dissolve from SAGA. Commented Nov 12, 2019 at 13:34
  • If you do not have a real topology error in your data you may suffer from an issue that is fixed lately. lists.osgeo.org/pipermail/gdal-dev/2019-October/050967.html. Unfortunately the fix is at the moment only in GDAL-master and you must either build GDAL yourself or download a ready made development version.
    – user30184
    Commented Nov 12, 2019 at 15:22
  • 1
    Can you share the file? This way it would be possible to see if there are other ways to solve the problem
    – Babel
    Commented Nov 14, 2019 at 9:37


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