[OSM-talk] Boundary rendering bug

Lennard ldp at xs4all.nl
Thu Feb 10 10:43:53 GMT 2011


> It's not really a bug, if you have the following setup:
[...]
> What you're telling mapnik is that there are two boundaries, one is
> admin_level 6, the other is admin_level undefined. The admin 6 one will
> render at z11 or closer, the undefined one renders at z9 to z11.

Correct. And at z11 only, both are rendered, leading to a more solid line
appearance.

> To map the boundary as a relation you should have:
>
> Member way:
> no boundary tags (that includes the boundary name)

Uh, no. Please, do add boundary=administrative + admin_level=n. Where n is
the highest order admin level that applies, so if two relations with
admin_level=6 and 8 respectively use that way, set admin_level=6 on the
way.

And, I hate to say it, read the wiki.

One of these days, I should just modify the mapnik stylesheet to use
osmarender's boundary handling (render boundary lines from ways alone),
and use the relations only for the name rendering. Bye bye overlapping*
boundary rendering!

* Which would bring so much goodness, that I wonder why I haven't done
that yet. :)

> Boundary relations are just specialized multipolygons once they reach the
> renderer so all the rules here apply:
> http://wiki.openstreetmap.org/wiki/Relation:multipolygon#Usage

Right, so why even bother with type=boundary when type=multipolygon will
do fine? :)

-- 
Lennard




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