[OSM-talk] Rendering issues with Carto 4.0

Jochen Topf jochen at remote.org
Wed Jun 21 20:06:48 UTC 2017


On Wed, Jun 21, 2017 at 05:25:28PM +0200, Maarten Deen wrote:
> I don't know if this was an issue with previous renderings too, but what I
> also see are multipolygons that do not have a way that is inside it as
> member. The inside way still renders but the style of the outer will also
> render over the inside way.
> Example here: http://www.openstreetmap.org/relation/2456565 where there is a
> lake in a woodland area which results in trees in the lake.
> 
> Is it possible to make a maproulette challenge for these cases?

This is a much more difficult issue to detect, because you have to
understand the different tags and how they interact. For instance,
drawing a building on top of a residential area is okay, you should not
cut out a space in the residential area for that building. But you have
to cut out a lake from a forest. There is no clear documentation what
these interactions are.

The other problem is that you need to do a lot of geometry operations to
find those overlaps. Not really difficult, but it is more effort than
just comparing tags on member ways and relations.

I want to do this at some point, but want to focus on the easier cases
first.

Also see https://github.com/osmlab/fixing-polygons-in-osm/issues/22

Jochen
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Jochen Topf  jochen at remote.org  https://www.jochentopf.com/  +49-351-31778688



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