[Talk-us] How accurate is Tiger data vs Yahoo Aerial?

[am12 at bolis.com]

Hi-  I've just joined up and I'd like to help out cleaning up the map for
my area in Beaverton/Portland Oregon.

It looks like it is completely covered already by the Tiger data.  But
I've noticed many displacement problems where the Tiger data doesn't line
up with the Yahoo aerial photos.

What I am wondering is: which of the two is more likely to be accurately
placed?  Are the Yahoo tiles pretty well positioned?  They look like they
fit together fairly well to me, but I don't really know.

I find that in some sections, the Tiger tracks line up with the Yahoo
photos exactly.  But then go a mile over, and the Tiger tracks are off. 
If I move the photo in Potlatch with space-and-drag, I can line them up
again for a section, but then they are off again elsewhere.

I'm sure the correct fix is some real GPS readings, and align both the
photos and tiger tracks to them.  But I don't have a GPS so I'm just
working off the Yahoo photos.

Any advice or suggestions?  Thanks.

- Alan