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I am editing a layer in QGIS with severe polygon overlaps. Is there a way to delete the underlapping portions (i.e. the invisible parts) using QGIS?

If I import the layer into GRASS using the GRASS-plugin, I can get a very useful layer which contains the overlaps (polygons_2), but if I use the difference geoprocessing tool to slice the overlaps from the original file, it naturally cuts away the overlap as well as the underlap, leaving holes instead of overlaps. I have also tried the v.clean functions in grass, but the overlaps are really too big to use snapping without distorting the data.

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I recommend SAGA Polygon self-intersection tool.

Image below is a single polygon layer, with multiple overlapping features (polygons). (Dodge blending mode is used to highlight overlaps, but it is simply green in normal display).

enter image description here

  1. Activate Polygon self-intersection tool from QGIS Processing Toolbox | SAGA | Vector polygon tools.
  2. Set id or any field to represent each polygon feature to identifier and hit [Run].

enter image description here

Done. All those overlapping (or underlapping) parts are now removed.

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