[OSM-dev] Advice sought on polygon-with-hole drawing

Paul Lenz paul at lenz-online.de
Fri Mar 14 06:33:36 GMT 2008

Hallo dev-request at openstreetmap.org,

> Send dev mailing list submissions to
> The island itself is just a simple, single polygon. 

No, it isn't. Big islands are divided into several "coastline"
polygons. If a such a polygon is not closed, you have to search
the whole data base for all following polygons which complete 
the island. Only after that, you know which side of the polygon 
is land and which side is water. Here you find a small map with
really big and complicated islands which even have small lakes:
I suppose it is a challenge for every renderer.


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