[Qgis-user] buffered polygons without overlaps

[Nicolas Cadieux]

« I'm sure there's got to be some combination of buffering, clipping, difference, intersection, union, and dissolve operations that will get me what I need, but I just can't visualise it. »
Yup!

If you can send me a copy or part of the files, I could have a shot at it and then give you the breakdown.  

Nicolas Cadieux
https://gitlab.com/njacadieux

> Le 2 mars 2023 à 12:48, Cory Albrecht via QGIS-User <qgis-user at lists.osgeo.org> a écrit :
> 
> 
> Hello,
> 
> I've been trying to find a way to buffer a bunch of touching polygons so that the touching sides get buffered, only the "outside".
> 
> I'm working off a shapefile of Scotland's 1930s civil parishes that I need to combine with another map of Scotland that has better coastal resolution and more complete islands. But the civil parishes map has a different coastline so I need to make that outer edge of the outer ring of parishes match the higher resolution coastline data, not worrying about the extra islands for the moment.
> 
> Regular buffer won't work, because all polygons will get extended and there will be overlaps.
> 
> I tried using this solution:
> 
> https://gis.stackexchange.com/questions/175599/buffer-neighbouring-polygons-without-overlap-using-qgis
> 
> but it didn't preserve the inner boundaries like I need. They ended up being wildly different.
> 
> I found a plugin "Buffer without overlaps" and it almost does what I need. It sections off the overlaps as separate polygons (with shrunken versions of the originals) but it consolidates those overlaps as one polygon that overlaps the two original polygons instead of two polygons split by the original border, so I cannot just dissolve them back together with some attribute filter.
> 
> 
> I'm sure there's got to be some combination of buffering, clipping, difference, intersection, union, and dissolve operations that will get me what I need, but I just can't visualise it.
> 
> I just use QGIS for a hobby, so I don't know all the neat computational tricks possible in the GIS field that I could use to do this, so any assistance or guidance on how to accomplish this task would be greatly appreciated.
> 
> Thanks in advance!
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