[OSM-dev] Getting admin_level=* from relations to render properly

[John Smith]

On 28 April 2010 19:00, Lennard <ldp at xs4all.nl> wrote:
> That cannot be solved from mapnik. This is a job to be done during the db
> import for mapnik, both for non-slim mode (a one off job) and slim mode
> imports, which have to take into account loading diff files. At some point,
> it just sounds much simpler to correctly tag the member ways. This is *not*
> wrong, they *are* boundary demarcation lines.

This can be solved in mapnik by using more selective query statements,
currently there is limited or no limitation placed on the admin
boundary queries... So yes this can be solved in mapnik/pgsql, however
I lack the SQL knowledge to fix it, or this thread wouldn't have gone
on for this long without a solution.

As for pre-processing being more efficient, possibly, but you need to
figure out the same sort of logic to figure it out in any case.

> By the time mapnik sees the data, it has been processed. Relations could
> have been converted into line geometries, and there is no way for mapnik to
> discern those from the proper ways, other than the test for osm_id>0. I
> suggest you play around with a limited dataset, and see how that ends up in
> the pg db, in which tables, for different taggings.

You are right about the osm_id, but I lack the ability to come up with
a suitable query to do the test, which is why this thread is still
going on.