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My goal is to create a buffer from a polygon. But the edges are the problem. That's the way I want it to look. So the goal is, that the edges are not connected. The example on the screenshot is done with PowerPoint, but I want to do it with QGIS, so I can do it for a lot of polygons at once.

Does anyone have an idea?

enter image description here

4 Answers 4

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Starting with a polygon (or several polygons):

enter image description here

Run the "Polygons to Lines":

enter image description here

Then "Explode lines". This won't look any different but if you enable "Show feature count" on the Layers list you'll see there are more features, like 4 for every rectangular polygon.

Then the "Single sided buffer" on the exploded lines will get you this as long as you buffer on the correct side, which for me was the "Right" side, seen here with the original polygon:

enter image description here

It might depend on which way round your polygon was digitised, in which case you might need to buffer both sides and then there must be another step to work out which one you need to keep...

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You can convert your polygons to polylines first and then perform a single sided buffer. Both are algorithms that can be found under Processing > Toolbox.

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    You also need to "Explode Lines" to convert the polyline into a set of single line segment features for buffering.
    – Spacedman
    Oct 11, 2018 at 14:11
  • @Spacedman, indeed, forgot to mention
    – PieterB
    Oct 18, 2018 at 7:31
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Taken from here: Have a peek at v.parallel, this might help you out.

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  • the problem is, that v.parallel only works with vector lines, not with polygones...
    – Simon
    Oct 11, 2018 at 13:56
  • But since you're clever you can convert your polygons to singular lines =)
    – Erik
    Oct 11, 2018 at 14:14
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I followed up the same process explained by @Spacedman, I use MMQGIS plugin, it makes me feel more comfortable with many more options under MMQGIS > Create > Create Buffers than the traditional buffering technique.

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