[OSM-newbies] Trust GPS or Yahoo aerial imagery?

[Richard Fairhurst]

Dave Clark wrote:

> Using Yahoo maps directly,  the "satellite" images have various
> copyright attributions. Images for my area indicate copyrights
> attributed to Aerials Express and i-cubed. Images in the UK are
> attributed to i-cubed and GeoEye. There's a generic attribution to
> Yahoo! Inc. on all of them. Yahoo has a personal-use only caveat in
> their terms of service, I am unaware of the license agreements as  
> to the
> images themselves.

Very very roughly, AIUI: the aerial imagery providers give a right to  
their customers (Yahoo included) to create derivative vector works.  
Yahoo has sublicensed this right to us. Their lawyers have checked  
this out and they're happy with it - and the OSM/Yahoo agreement has  
had sufficient publicity that, if the imagery providers had problems,  
you can bet we'd have heard about them by now.

To answer the original question, though, trust your GPS over the  
imagery. The imagery may not always be rectified, whereas as long as  
your GPS has produced a good-quality track - i.e. no "concrete  
canyon" distortions - it should always be accurate.

cheers
Richard