2015-11-26 20:24 GMT+01:00 Colin Smale <colin.sm...@xs4all.nl>: > I use the subarea member because it makes cross-checking easy. Have all > the lower-level boundaries in my higher-level admin area been added to OSM?
what comes next? Have all the roads in a given administrative area listed with an "administrates" role in the relation? Cross-checking to me sounds like unhealthy redundancy here. It means having to do the work twice and having the information stored double. Unfortunately the various admin levels do not always form a strict > hierarchy. A small area at (lets say) admin_level=10 might be enclosed > spatially by entities at level 8, 7, 6, 5 etc but it only has a direct > administrative relationship with one of them, which might not be the > next-highest level (next-lower number). > in which way does a subarea role help here to solve real problems? Which administrative aspects/powers/relationships/fields are those that are looked at? Do you have concrete examples? Finding the boundaries of all districts within a county (UK example) > becomes trivial with the explicit parent-child link. yes, that's the one usecase that becomes easy. And all other mappers and users have to care for all those subareas and have their mapping more complicated just to facilitate this one usecase? > Otherwise its like finding all boundaries with admin_level=8 which are at > least 99% contained by the higher-level boundary. That sounds > computationally a lot more complicated to me. Why not 100%? Because > sometimes the boundaries at different levels are not imported/drawn from > the same source, leading to the boundaries not being exactly coincident. so because the data is not sufficently precise you decided not to fix the data but to keep separate hierarchy lists (aka relation membership) as a workaround? Cheers, Martin
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