QGIS 2.18.5

I've created a viewshed over a hilly area and I would like to add a fixed distance buffer just to compensate for any underestimations from the viewshed plugin's result.

This is the result with a 100m buffer:

enter image description here

You can see the buffer does not work if the feature has holes in it. Some of the holes are quite large and if filled, will alter the viewshed drastically.

I've also tried the solution from this thread: Fixed buffers and interior buffers are not working for a polygon that contains a hole

However I get this result:

enter image description here

enter image description here

enter image description here

Any ideas how to fix this?

  • 1
    Perhaps some polygon geometries are not valid. Check the topology first. – user30184 May 17 '17 at 10:32
  • 2
    Also make sure you don't have any active selections on the layer you are buffering – MappaGnosis May 17 '17 at 10:39
  • All geometry types are WKB type: "Polygon" No selections are made prior to buffering – James B May 17 '17 at 11:05
  • @JamesB - Try the Fill holes algorithm from the Processing Toolbox. – Joseph May 17 '17 at 12:13
  • @Joseph I've just updated the question as you posted your comment. How about a means to split the features instead, thus splitting the closed holes. – James B May 17 '17 at 12:14

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