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I have a database with topological error. In particular I have an overlay of polygons. I would like to correct these errors.

I thought to use an automatic procedure since I have a lot of errors. I thought to use the v.clean command in grass (I use QGIS).

The command works well but it creates many additional geometries.

Is there a method to avoid this problem? image1 image2

  • Are overlays errors or should there be some? Post some printscreens of errors and what settings you used on v.clean. Also check this post, it might help: gis.stackexchange.com/q/324211/16109 – Mat Jun 8 at 13:15
  • Hi! thanks for your answer. I update the question with 2 image of my situation. I'm working with a large database of polygon. I tried to run v.clean algorithm from qgis platform with the standard option. Also, I tried to run command from Grass, in this case I used the following command: rmdupl,rmdangle,snap,rmdac,prune,rmsa. The command seems to function, I obtained at the end this warning message: number of incorrect borders: 2922 and number of centroids outside the area:2048. – matte85 Jun 8 at 14:12
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Use the Geometry Checker plugin. Just leave the the value of "Check for overlaps smaller than ..." equal 0.0 and run. In the next window, click "Fix selected errors using default resolution". Take a look here, it might help.

Geometry Checker is a core plugin, so it is already installed. You just need to go to activate it in the Plugin Manager. Go to the installed tab and click on Geometry Checker. Take a look here.

  • OP stated that v.clean was not a solution. Without a much more explicit answer, this Answer may be deleted as low-quality. – Vince Jun 8 at 23:19
  • @Vince, you were right. I usually fix this problem using v.clean under my own PyQGIS algorithm, that's why I said to use it. Considering that the solution was vague, I suggest to use the Geometry Checker plugin. – lcoandrade Jun 9 at 2:17
  • thanks a lot for your answers! I use the qgis version 3.6 and I can't find this plugin. Do you know a plugin for this version? or should I install the previous version and then 2.18? – matte85 Jun 9 at 8:11
  • @matte85, Geometry Checker is a core plugin, so it is already installed. You just need to go to activate it in the Plugin Manager. Go to the installed tab and click on Geometry Checker. Take a look here: docs.qgis.org/2.8/en/docs/training_manual/qgis_plugins/… – lcoandrade Jun 9 at 11:53

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