+1, spent a lot of time debugging issues when a tag from outer leaks into multipolygon itself.
Also, I'd prefer to use not non-deleted tags, but the whole set of tags, as I'm currently using a stlyesheet with a large deletion list. This would make geometry interpretation stylesheet-independent. 2014-06-13 2:25 GMT+03:00 Paul Norman <penor...@mac.com>: > Osm2pgsql currently tries *very* hard to turn multipolygon relations into > geometries. It currently detects two types of MP relations, new-style and > old-style. A new-style MP has tags on the relation while an old-style MP > only has type=multipolygon on the relation and relies on the ways for the > tags. > > It then tries to deal with odd tagging in various ways. MP handling is one > of the biggest sources of osm2pgsql bug reports[1] and a big time-sink. > > One of the bigger issues is moving tags from ways to MPs that are falsely > detected as old-style. This is an attempt to interpret flawed tagging. > > I think we need to move to a more strict parsing of MPs, accepting only > new-style MPs and old-style MPs where all outers have identical > non-deleted[2] > tags and the relation itself has no non-deleted tags. > > Osm2pgsql is not just a consumer of data, it is one of the main feedback > tools, so it is strongly integrated into the feedback cycle, so if osm2pgsql > doesn't process a multipolygon, a mapper will likely correct the tagging. By > doing this, it will make it easier for those interpreting raw OSM data. > > To support this, I looked for some numbers. Using a shortened deleted tags > list, there are 1 million new-style and 261k old-style MPs. Of the > old-style, > 256k have a member with role outer. 251k of these have entirely consistent > tags on outers, while 2.3k have two sets of tags among the ways. About 180 > have three or more.[3] An old-style MP without entirely consistent tags on > outers is ambiguous and in error. > > [1]: > https://github.com/openstreetmap/osm2pgsql/search?q=multipolygon&type=Issues > [2]: A deleted tag is one such as source that osm2pgsql is dropping > [3]: https://gist.github.com/pnorman/ebd41f5a1759916a48b5 > > _______________________________________________ > dev mailing list > dev@openstreetmap.org > https://lists.openstreetmap.org/listinfo/dev -- Darafei "Komяpa" Praliaskouski OSM BY Team - http://openstreetmap.by/ xmpp:m...@komzpa.net mailto:m...@komzpa.net _______________________________________________ dev mailing list dev@openstreetmap.org https://lists.openstreetmap.org/listinfo/dev
