[Tagging] Waterway river vs stream

Christoph Hormann chris_hormann at gmx.de
Sat Oct 19 20:13:04 UTC 2013


On Saturday 19 October 2013, Jonathan wrote:
>
> It seems a river is something that has a source and a mouth (either
> where it joins the sea, lake or a larger river).  So I would say that
> only streams that have been named "River ...." or "The River ..."
> should ever be tagged as a river, everything else is a stream.

Be careful here - different languages use different distinctions and 
even in English use of the terms might differ by country or region.  
And of course duplicating information that is already in the name tag 
is not necessary.

> One option might be to tag every natural watercourse water=stream and
> strahler=[1...12] and then let the renderer choose how to display it
> based on the strahler order?

No, first of all this kind of topological measure is not possible to 
determine locally by the mapper since it depends on the whole river 
system upstream from the point in question (and even more: it requires 
complete data of it).  Second it is not suited for use in map rendering 
from a cartographic viewpoint.

I explained the requirements for an importance rating for rendering of 
rivers in:

http://www.imagico.de/map/water_generalize_en.php

The only really important thing for allowing good rendering of the 
waterways is to have correct orientation and connectivity of all ways - 
which is a huge problem in the OSM data, in my opinion one of the most 
severe we have (together with the notoriously broken boundary relations 
maybe).

Greetings,

-- 
Christoph Hormann
http://www.imagico.de/



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