[Tagging] Lakes, islands and multipolygons

sly (sylvain letuffe) liste at letuffe.org
Fri Oct 16 11:45:50 BST 2009

On vendredi 16 octobre 2009, Jukka Rahkonen wrote:
> Currently big lakes in Finland have been tagged as coastlines which is a
> good workaround and looks correct in slippy maps.  However, it is not
> right, because they are not seas but just lakes.  

I would myself prefer to use something else to make it easier to tell appart 

We have 
* natural=coastline
* waterway=riverbank

what about something like natural=lakebank or lakeline or waterline to define 
lake's bank

(Then put all that in a multipolygon relation natural=water)

> By the way, why do we call all polygons having holes as multipolygons,
> even if they have only one outer ring? But of course they can be
> considered as simple multipolygons.

The "multipolygon" name of osm was probably not perfectly choosen ;-)
It's a "describe them all" from 1 to n polygons. It's not multipolygon in the 
GIS sense but hey, does that matter ?

Sylvain Letuffe liste at letuffe.org
qui suis-je : http://slyserv.dyndns.org

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