[Qgis-user] Removal of overlap geometries within the same layer - merge to largest neighbor polygon

[Nyall Dawson]

On Tue, 25 July 2023, 8:02 pm Andreas Neumann via QGIS-User, <
qgis-user at lists.osgeo.org> wrote:

> Hi,
>
> A friend of mine has a dirty input data set with lots of overlapping
> geometries (within the same layer) and asked me if there is a tool within
> QGIS to automatically remove the overlaps and assign the overlapping area
> to the neighbor polygon with the largest area.
>
> The solution was surprisingly hard to find, although I am pretty sure
> there are multiple combinations of algorithms that would solve the problem.
> Here is the solution I came up with: https://github.com/qgis-ch/overlap_removal/tree/main
> - perhaps you have better ideas - more elegant solutions?
>
> Wouldn't it be great if QGIS had a processing tool to solve this overlap
> cleaning within the same layer "out of the box" without having to use a
> graphical model or a more or less complicated sequence of algorithms in the
> processing toolbox? Apparently, ArcGIS has such a tool ...
>
> Saga and GRASS also might have such tools - but I couldn't get the SAGA
> based QGIS plugin "Dissect and dissolve overlaps" (
> https://plugins.qgis.org/plugins/dissect_dissolve_overlaps).
>
> The same problem exists for automatically filling small gaps in the
> polygon data set ...
>

The recently introduced geos tools for coverage layer cleaning and
simplification seem like a good fit here! See eg
https://lin-ear-th-inking.blogspot.com/2022/08/validating-polygonal-coverages-in-jts.html?m=1

These tools would ideally be exposed through the qgis processing toolbox.

Nyall

Andreas
>
>
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