[OSM-talk] Retaggin of ways

Tom Hughes tom at compton.nu
Thu Dec 6 08:37:28 GMT 2007


In message <1196890008.22494.33.camel at localhost.localdomain>
        Jon Burgess <jburgess777 at googlemail.com> wrote:

> You need to be careful about the relative accuracy of different sources.
> I believe that GPS traces are generally more accurate for road positions
> than Yahoo! imagery (especially if there are several GPS traces covering
> the same road). 
>
> Adding roads based on Y! when there are no other traces is fine but
> please don't re-align existing roads just to fit the Y! images. 

I do it all the time as it generally gives a much better idea of the 
true shape and position of the road then the GPX trace which will
often be (a) off to one side if you were walking/cycling or (b) will
tend to smooth out the curves just because you will shortcut them
when possible when driving/cycling.

I do have the advantage of having lots of evidence (from comparing
traces with imagery) that the imagery round me is well positioned
though, and obviously if I had reason to believe it wasn't then it
would be a different story.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://www.compton.nu/




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