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I want to use the intersection tool in QGIS version 2.18 for two layers:

  1. Corine land use data downloaded from: http://land.copernicus.eu/pan-european/corine-land-cover/clc-2012 (a geodatabase, vector format)
  2. buffer layer in vector format.

When I try to use the intersection tool, I get an error:

"Input layer A contains invalid geometries (feature 1255). Unable to complete intersection algorithm."

Layer A is the Corine layer.

How can I get rid of this error and use the intersection tool properly?

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7
  • Check this. You need to correct invalid features before to apply intersection tool.
    – aldo_tapia
    Jul 21, 2017 at 14:36
  • @aldo_tapia Thanks, but for some reason I can't toggle the editing mode for the Corine layer.
    – Iris
    Jul 21, 2017 at 14:48
  • Did you download the Esri Geodatabase or SQL database format?
    – aldo_tapia
    Jul 21, 2017 at 15:41
  • @aldo_tapia I downloaded the Esri Geodatabase format.
    – Iris
    Jul 21, 2017 at 16:27
  • You can select what you want to use (based on layer B extent) and go to save as using save selected features and create a new vector layer. After this, you can edit the new layer and delete invalid geometries (you also can use Topology Checker Plugin to identify those errors)
    – aldo_tapia
    Jul 21, 2017 at 16:42

1 Answer 1

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I finally got over my problems. Downgrading to QGIS 2.14 Essen helped me get rid of the invalid geometry problems (for some reason using the tips here: https://faunaliagis.wordpress.com/2013/08/14/bad-bad-polygon-fixing-invalid-geometries-with-quantum-gis/ didn't get rid of all the problems) and then I used clip function instead of intersection.

Also, I had some problems with changing projections and I finally figured out that changing layer CRS does not work as I wanted, but saving a new file with the projection I want worked. :)

Oh, and if anyone is doing something similar with Corine, it might be worth to check that you don't have any features in multiple buffer zones (happens if the buffers are really close). In that case you can use multipart to singleparts function.

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