On 27 November 2010 06:25, Ed Avis <e...@waniasset.com> wrote: > For addressing, I guess it is usually sufficient to have a street name - > the > exact addr:housenumber stuff is not needed I assume? > Something I can comment on (speaking as just me, not nearmap for once!) having been looking recently at some feedback from people relating to searching done using OSM data; unfortunately street isn't good enough. As SteveC points out in a later reply, some places have roads that are very long; the Albany highway in WA is 410km long and the numbering runs from around 51 in Albany to 2500-odd up near Perth, meaning that locating the Chicken Treat in Albany just by street name is subject to a considerable margin of error. Assuming that you'd ever want to locate a Chicken Treat.
As Martijn van Exel comments, a good approach is to have start/end numbers per segment (or per block in cities) so that it's at least possible to get close to a number. Gathering number data at the junctions of streets is a darn sight quicker than doing a whole street, and gives a good gain in address accuracy for a smaller investment of time. I managed to do junction numbers for a large chunk of the suburb I live in in only about twice the time it took to do the street I live on (having to check numbers for subdivided plots slows things down a lot). > OSM already has plenty of tools for 'noname' hunting but it is harder to > track > down streets which are missing from the map altogether. Another problem which crops up in WA, especially at the fringes of the metro area where there's lots of house-building going on; new streets appear almost without warning. This is something that could be assisted with processing of satellite or aerial images to identify roads - where there appears to be a road and there's no corresponding road in your database, that's where you concentrate your checking. Turn restrictions are also hard to survey manually. A mapper on foot or > bicycle > might not pay much attention to them, and again, it is hard to know when > you have > all of them. They might possibly be suggested from analysis of GPS traces, > provided we have a large number of traces for an area and they are clearly > tagged to show which ones are for travelling by car. This is one reason > why a > standard tagging scheme for GPS traces is needed. > Or some of them can be spotted if you have decent resolution images to check, for example: http://www.nearmap.com/?ll=-31.955045,115.850815&z=20&t=k&nmd=20090702(helps if you can find an image where the cars don't obscure the arrows on the road). If I were Google, I'd have been capturing road markings and signs as part of Street View for eventual extraction of this sort of data from day one: http://maps.google.com.au/?ie=UTF8&ll=-31.954799,115.850835&spn=0.001047,0.002064&t=h&z=20&layer=c&cbll=-31.954886,115.850879&panoid=INN-K7Gt8NKz7PkL9V5r9Q&cbp=12,160.76,,0,17.22 Getting back to the question of metrics; as a manager in my day job I've had to deal with measuring odd stuff for years - in the case of maps, I'd suggest following a Tom Gilb-esque approach and track the number of error reports that turn out be valid, by area, corrected for map density. In other words, one measures how accurate the map is in use. Unfortunately, I doubt that those sorts of figures would be released by a commercial map data provider. Finally (and echoing SteveC again), I'd give a +1 to the ability to do geocoding (both directions) as the #1 difference between current open mapping projects and commercial data. But routing (by which I mean full endpoint-to-endpoint connected routing, cross-border, including public transport and other non-road links) would be a pretty close second. Cheers Ben -- (speaking only for myself, not nearmap)
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