On Mon, 12 Jan 2009 16:34:34 +1030 Jack Burton <[email protected]> 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 :/ >I haven't seen it in broad use in > Australia [everyone else: please show a good Aussie example for Ben if > I'm wrong on that], but in a handful of places where there are ways > without other tags [that define physical characteristics] used in the > relation-based approach, I've added this approach in parallel, to make > it easier to identify what the ways are there for (i.e. without having > to look up what relations they belong to) without breaking the > relation-based approach. You doing this has always struck me as a little odd given the relationship data gives the relevant data anyway ;) > 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! 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. > 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. In my working mapping between Gawler & Riverton it's driving me crazy because there's absolute no way to find the information except via government sources which as jackb says are encumbered. :( (And real estate doesn't seem to move quickly enough out that way to give a plethora of online addresses ;) -- =b _______________________________________________ Talk-au mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-au
