[OSM-dev] Algorithmic Problem

Bernhard R. Fischer bf at abenteuerland.at
Tue Dec 4 08:45:09 GMT 2012


On Thursday 22 November 2012 13:39:40 Bernhard R. Fischer wrote:
> I'm working on Smrender, a renderer for paper (sea) charts. I encountered a
> specific problem.
> 
> Does anybody have a suggestion on how to determine if a node is either on
> land or on the sea in the special case if the OSM data does not contain
> any piece of a coastline?
> 
> Thanks in advance,
> Bernhard


I now implemented the following solution. It does not involve to have 
prerendered data or similar approaches.

If the osm data to be rendered does not contain any coastline I look for 
objects which are tagged in a way which cannot exist on the sea such as 
natural=water+water=lake|river or building=*.

This works fine except in the corner case where an empty page shall be 
rendered but this case typically will not occur because Smrender is intended 
for users to create paper charts. I assume that typically one will not try to 
render an empty chart ;)

Bernhard
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