[OSM-talk] Islands

David Groom reviews at pacific-rim.net
Sat Apr 14 02:16:49 BST 2007


I don't know :)

I've been meaning to update the large rivers page [1] to get debate going on the whole large rivers  / lakes idea, which would include a discussion on how to render islands.

Straying away from your initial question, and looking at large rivers, Osmarender currently renders large rivers, but the Mapnik layer does not.

As I understand it Mapnik needs a proper polygon to generate the fill and so does not generate a filled wide river from the proposed rendering on the large rivers [1] page. Own its own this is fairly easy to implement.

Moving now to your question about islands :

It is, as far as I can see, fairly difficult to intuitively split a river with islands in it into polygons (particularly where there are many islands close to each other) , where each polygon would be a continuous way and there is not a complicated system of segments going between the riverbank and each island.  

I'd like to see a modification of my proposal on the large rivers page [1] where riverbanks would be drawn as a polygon with a tag something like waterway = riverbank, and islands in these rivers would be drawn as waterway = riverbank; island = yes.  Given this suggested rendering, island in lakes could be tagged exactly the same as islands in rivers and they would still render correctly.

David


[1]  http://wiki.openstreetmap.org/index.php/Proposed_features/Large_rivers


  ----- Original Message ----- 
  From: lewispusey 
  To: talk at openstreetmap.org 
  Sent: Friday, April 13, 2007 5:08 PM
  Subject: [OSM-talk] Islands


  What is the current best way to draw and tag islands in rivers and lakes?
  Lewis


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