[OSM-talk] osm2pgsql multipolygon parsing

[Peter Wendorff]

Am 24.09.2013 10:12, schrieb Stefan Keller:
> 2013/9/23 Kai Krueger <kakrueger at gmail.com> wrote:
>> Indirectly it is a question of tagging schemas.
> 
> To me this is actually indirectly a question of a proper area type!
> See e.g. "Towards an Area Datatype for OSM" from Jochen at SOTM
> http://lanyrd.com/2013/sotm/scpkrr/
+1
But the transition necessary is the same:
IF we could come to a stable, but backwards compatible solution by
step-by-step hardening the current multipolygons it would be easier to
create a new area datatype later converting multipolygons on the fly.

While it is NOT possible overall to convert ways to polygons later (as
you would have to do that tag-based, and have to make sure to duplicate
it if there are line-tags and area-tags on the same way and so on), it
might be possible to auto-convert multipolygons to area; but to do that
multipolygons have to be clearly defined and possible to handle.

The discussion of this thread tackles the problem left for any such
conversion in future: What is the area described by any given
multipolygon with the given tags on inner/outer/relation?

If we could come to a clear consensus about that, and if we could slowly
enforce fixing any problems according to that in the data, then a
conversion to a new area data type could be done with less errors and
problems than it could be done now.

But thanks for the area datatype argument, as it's an additional
argument to strenghten the Multipolygon definition and -interpretation
for the current (or very near future) osm.

regards
Peter

> 
> --Stefan
> 
> 
> 2013/9/23 Kai Krueger <kakrueger at gmail.com>
> 
>> "Petr Morávek [Xificurk]"-2 wrote
>>> Anyway, this thread was not started to debate tagging schemes, the
>>> question I (and others) wanted to discuss here is this:
>>> Given the data that are currently in the database, how should osm2pgsql
>>> handle the import to get as much as possible multipolygons right?
>>
>> Indirectly it is a question of tagging schemas. With osm2pgsql being the
>> tool used in the default map rendering on osm.org and the prevalence of
>> "tagging for the renderer" decisions on how it handles multipolygons will
>> (and imho to a limited degree should) influence how people tag and what
>> they
>> perceive as correct tagging. Therefore it is important that there is a
>> consensus of what the correct tagging schema is and make sure that is
>> correctly supported by osm2pgsql. That is also why I think having this
>> discussion on talk, rather than on github or the dev list is appropriate.
>>
>> We need to come to a consensus between all of the main tools (at least iD,
>> P2, JOSM, osm2pgsql, osrm, ...) and the mappers to what the preferred,
>> encouraged and supported standard for tagging multi-polygons is and make
>> sure that all documentation is in line with this.
>>
>>
>>
>>
>>
>> --
>> View this message in context:
>> http://gis.19327.n5.nabble.com/osm2pgsql-multipolygon-parsing-tp5778300p5778654.html
>> Sent from the General Discussion mailing list archive at Nabble.com.
>>
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