[postgis-users] MultiPolygon -> Polygon

[Birgit Laggner]

Hi James, 

perhaps you could split the data per multipolygon into the largest polygon and the rest. Then buffer the smaller polygons by a small amount and union them with the large polygon? 

Regards, 
Birgit 


Von: "James Sewell" <james.sewell at lisasoft.com> 
An: postgis-users at lists.osgeo.org 
Gesendet: Montag, 6. August 2018 09:24:42 
Betreff: [postgis-users] MultiPolygon -> Polygon 

Hi all, 
I have a set of LineStrings which are being turned in Polygons (most of which are invalid). 

I can clean these (makevalid or buffer), but then some of them result in MultiPolygons (which makes sense - mostly small bowties). 

I'm looking for the easiest way to get a single Polygon from each of these MultiPolygons - I can tolerate a small amount of change in area (up to 5%). 

I've tried small just keeping the largest poly, buffer(small_number) and concavehull but nothing seems quite right. 

Any ideas? 

Cheers, 

James Sewell, 




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