On Mon, 2009-01-12 at 17:06 +1030, Darrin Smith wrote: > [On the single area option] > > > Personally I think that is still the best approach (the only downside > > I can see with it would be if a suburb was not defined by a closed > > area - although I'd imagine that would be quite rare). However, > > you'll find plenty of others that prefer one of the other two > > approaches. > > Yeah I'd have to say I actively dislike this approach because it > encourages more and more cases of stacked ways. There's places in > northern Adelaide where 1 road would end up with 6 additional ways > stacked on top of it to represent this setup :/
... > > But when the boundaries (or more often, parts of them) are just > > imaginary lines, creating multiple ways just for a boundary, then > > grouping them together as a relation seems like an awful lot of > > double handling (both for the mapper putting them in the map and for > > any automated process trying to reassemble them for any useful > > purpose). > > For the mapper I'd say this approach is much easier than trying to > untangle up to 6 areas stacked on top of each other on a common > boundary, 8 along a state boundary! In JOSM, it's fairly simple to see all stacked ways (using the middle mouse button, with control to hold/select) - then (as long as the ways have been tagged) it's very easy to pick the one you want to work with. Not sure whether it's that straightforward in the other editors or not. Also straightforward when working with raw OSM data (again, particularly if the ways have been tagged). With the single area approach, you only ever have to worry about one way per suburb, but you often have to deal with a few stacked ways. Conversely, with the other two approaches, you only have one way in any given place on the map, but you often have a whole swag of boundary ways per suburb. So I guess it's really a case of 6 of one, half a dozen of the other... > And 0.6 api relations are ordered, post-processing of them is > about to become remarkably easier once clients start putting in the > members in order. That sounds more promising. > > Darrin's mapped most of Adelaide's nothern suburbs using this method, > > and that's probably the best Australian example of using relations for > > suburb boundaries (as well as postcode & local government boundaries). > > And haven't I been banging my head against a wall trying to find useful > data to do it, council signs only go so far... > > > But surveying those "imaginary line" parts of boundaries, > > particularly in areas where there are no houses or businesses close > > enough to the estimated boundary to be authoritative is a bit more > > problematic - I haven't come up with a good method yet; perhaps > > someone else on the list can suggest one? (the Government - including > > Aussie Post - published data all appears to be encumbered). > > Yeah, this has caused me the greatest trouble in northern Adelaide as > some areas really are vague. I've opted in the end to use a best guess > estimate of where they lie, following on from someones comment a month > ago when talking about adding roads, that a straight line linking 2 > points where a road run was still accurate at some level. > > My thinking goes - If I know at this point these 2 places are either > side of the boundary and over there those 2 places are then it's > reasonable as a first cut to just link the two points and hope someone > gets some better data later to follow the exact lines. Sounds resonable enough (presumably tagged with source=extrapolation or similar). At least that way, suburb boundaries can be completed. Cheers, Jack. _______________________________________________ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
