On Fri, 12 Jun 2009, Delta Foxtrot wrote: > > I've come to the realisation that every road (and > > everything that was placed in reference to the roads) in the > > suburb where I live is out by about 8-10m. Much of > > Brisbane's road system seems to have been traced off the > > Yahoo imagery, apparently without aligning it to fixed > > points before hand. > > 8-10m isn't that much of an error to be honest. There really isn't any such > thing as perfect data if you are using consumer grade equipment of any > sort, things will improve over the next 10 to 20 years with other > constellations of GPS like sats starting to broadcast, but until then 10m > is as good as it gets for the most part for most things unless you spend a > lot of time getting very very accurate positioning.
There are definitely suburbs in SW Sydney where we have seen the same - the photos have not been aligned with any known points. There are tricks in JOSM for moving these areas en masse - can't confirm for any other editor. I think that often the amount was greater than 10 metres. But we aren't making a perfect plan of the area - we are making a map, and to me it is an aid to navigation, so the exact placement is not as important as the relative positions of the objects. But we can improve the accuracy over time as DF notes.
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