On Fri, Jan 1, 2010 at 6:49 PM, John Smith <[email protected]>wrote:
> 2010/1/2 Aun Johnsen <[email protected]>: > > Even if you have access to good arial photography, remember that it might > be > > out of alignment, it can be a good advise to gather some good fixes to > check > > the alignment of your photos, this can be several GPS tracks along your > > trail. > > I'm pretty sure the imagery he's refering to is nearmap.com, which I'm > not sure how they manage it exactly but they seem to be about > sub-metre accuracy... > Where are you getting that "sub-metre accuracy" claim from? This thread ( http://www.mail-archive.com/[email protected]/msg03414.html), which you contributed to, throws out "3-5 meters", "1-4 meters", and "5 meters or so". This seems like somewhere that the wisdom of crowds actually applies. I think I'd trust the average of a bunch of independent GPS traces to a single orthorectified aerial - especially in an area which isn't extremely flat. But I guess I might be convinced otherwise, if I'm actually shown the "sub-metre accuracy" claim, which presumably outlines the methods utilized to ensure such accuracy.
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