multiple overlaps (>2) between polygons

[Antonio Valanzano]

Hi members, 

I have the problem of cleaning some polygon data .

They present several overlaps  and I want to clean them removing the overlaps and retaining all the attributes of the original polygons.

 

 

The solution I have been able to realize is based of the indication I have found at this link

https://blog.cleverelephant.ca/2019/07/postgis-overlays.html

 

This solution requires several steps:

-          Extracting  the exterior rings

-          Unioning  them to create a multilinestring composed of linestrings splitted at intersections

-          Polygonizing  the multilinestring in order to create a multipolygon

-         Converting the multipolygon  to separate polygons each one with the number of overlapping origins

I wonder if a more direct solution could be possible.

 

Regards

Antonio

 

[a.fu...@lqt.it]

On Fri, 20 Dec 2024 00:04:13 -0800 (PST), Antonio Valanzano wrote:
> This solution requires several steps:
>
> - Extracting  the exterior rings
> - Unioning  them to create a multilinestring
> composed of linestrings splitted at intersections
> - Polygonizing  the multilinestring in order to
> create a multipolygon
> - Converting the multipolygon  to separate polygons
> each one with the number of overlapping origins

> I wonder if a more direct solution could be possible.
>

Hi Antonio,

the only alternative that comes to mind is to create an
ISO Topology ... but I sincerely doubt that it could be
considered a simpler or easier solution

bye Sandro

[Maurizio Trevisani]

The problem is not only the multiple overlaps, where you could decide to eliminate those arcs which separate a polygon from an overlap chosing the polygon to aggregate the overlap (from the two or more adjacent) which has the highest circularity, but also the more difficult problem of the holes (where I guess you need some editing to add missing arcs).

Try to clip the original linestrings by the original polygons to get correctly modem all the arcs.

Bye,

Maurizio Trevisani 

Il giorno 20 dic 2024, alle ore 09:04, Antonio Valanzano <anva...@gmail.com> ha scritto:



Hi members, 

I have the problem of cleaning some polygon data .

They present several overlaps  and I want to clean them removing the overlaps and retaining all the attributes of the original polygons.

 

<polygon_overlapping.jpeg>

 

The solution I have been able to realize is based of the indication I have found at this link

https://blog.cleverelephant.ca/2019/07/postgis-overlays.html

 

This solution requires several steps:

-          Extracting  the exterior rings

-          Unioning  them to create a multilinestring composed of linestrings splitted at intersections

-          Polygonizing  the multilinestring in order to create a multipolygon

-         Converting the multipolygon  to separate polygons each one with the number of overlapping origins

<new_polygons.jpeg>

I wonder if a more direct solution could be possible.

 

Regards

Antonio

 

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<polygon_overlapping.jpeg>

<new_polygons.jpeg>