[postgis-users] Topology: Simplifying Coastlines with Islands

[Michiel J. van Heek]

Quoting Sandro Santilli <strk at keybit.net>:

> On Tue, May 29, 2012 at 03:23:06PM +0200, Sandro Santilli wrote:
>
>> I recon that for long island, splitting the unsimplified edge on
>> the closest point to the island might make it simplifiable.
>> Probably a single point is not enough for the Brazil case, but
>> a recursive approach would find next closest point and succeed.
>
> Just wanted to get back on this as I think it's the logical continuation
> of the SimplifyEdgeGeom approach. On "collision" exception you would
> basically have the information about the edge being simplified (let's call
> it "E") _and_ the colliding obstacle (let's call it "O", be it a node or
> edge).
>
> You would then compute the closest point of "O" onto "E" and split "E"
> by that point. Then re-run on each of the sub-edges "E1" and "E2" resulting
> from the split.
>
> Re-joining the sub-edges after simplification may or may not be something
> you'll want to do within the same function.
>
> I'll love to know if such approach would have all the required lower-level
> editing functions in place.

Hello Sandro,

Just want to let you know that I did not have the opportunity to  
proceed with this. Extremely busy with other work. Sorry about that. I  
hope to be able to look into topology again a few weeks from now.

Best regards,
Michiel.

P.S. The reason that my function only selects faces with a single  
edge, is it aims to delete islands, completely surrounded by sea.  
Small coastal islands practically always consist of only one edge.