When I selecting features to merge in QGIS 2.14.3-Essen using "merge selected features", I sometimes get "dirty" results with redundant polygon vertices. Is there an ex-ante or an ex-post way to get rid of them? Using Mac OS 10.11.6 El Capitan

Before After

  • 1
    Those vertices aren't redundant, they're there because your input polygons don't share the exact same border. You'd get the same result merging them in another GIS.
    – Dan C
    Feb 10, 2018 at 14:20

1 Answer 1


Those gaps are produced because during the digitizing process the "topological" option is not enabled. Hence borders must be redrawn instead of being used as a reference for the new polygon.

There is a simple and quick approach to solve the problem. Here is a demonstration with a polygon layer with the same issues:

1) First the original shapefile, with Chilean administrative regions.

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2) After enabling editing mode and merge two regions gaps appear.

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3) In editing mode again you could use the 'Node Tool' in order to select the vertices of those gaps.

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4) Finally, press Supr to delete the vertices and consequently the gaps.

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  • This fixed my issues, thanks so much for explaining.
    – A. Prok
    Mar 7, 2018 at 21:19
  • Great! If it was helpful, you could accept the answer using the tick symbol.
    – gtapko
    Mar 14, 2018 at 2:25

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