[Tile-serving] [osm2pgsql] Don't let invalid geometries into the database (#428)

[SomeoneElseOSM]

I'd definitely agree that there's a need for wider discussion here, and that probably doesn't need to come from a code perspective (most mappers see the osm editors and the results on the map styles on osm.org, and that's it - they're unaware that osm2pgsql even exists, let alone the role of it, its -G flag and which map layers on osm.org use it).

Perhaps a way forward would be to create a bunch of "invalid but potentially meaningful to humans and/or mapnik" multipolygons on the api06 dev server and link to it in an osm.org diary or blog entry and talk@ list post so that people can look at the data (with the data layer on), and edit it to get a feeling for what this change will do?  

It'd probably also need a discussion of what sort of geometries osm2pgsql considers invalid and why.  "inner hole outside outer way" is an obvious one that's easy to describe but I suspect there are others too and without going through the code mappers won't know about them.

Because there are people created and "correcting" invalid geometries all the time "what's currently invalid in the planet" is always going to be a bit of a finger-in-the-air test.

(quotes around "correcting" because obviously it tends to be "remote mapping" - changing the data to something that a QA site likes, not necessarily to what exists on the ground)

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Reply to this email directly or view it on GitHub:
https://github.com/openstreetmap/osm2pgsql/pull/428#issuecomment-129373021
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