[postgis-users] Topology: Simplifying Coastlines with Islands

[Michiel J. van Heek]

Dear list,

I am trying to simplify a dataset of country boundaries by using  
topology functions, as described in Strk's Blog:  
http://strk.keybit.net/blog/2012/04/13/simplifying-a-map-layer-using-postgis-topology/

This has worked quite well, except for coastlines with islands nearby.  
The simplified coastline would probably intersect the island, or pass  
the island at the wrong side, leading to invalid topology. Does that  
mean that countries with coastal islands such as Canada and Norway  
(see attached image) cannot be simplified this way?

Ideally, islands in the way of a to-be-simplified coastline should be  
merged with the mainland. (I have already removed the smaller islands,  
but I think I should not remove the bigger islands too.)

Best regards,
Michiel.

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