[Qgis-user] buffered polygons without overlaps

[Cory Albrecht]

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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