OpenStreetMap
Too much rain to do any riding so I am stuck inside using the Bing layer.
I don't know about other places, but here in Korea, although usually having better resolution than Yahoo, it is often out of alignment as much as or worse than Yahoo. And it is usually not a one quick fix solution. Now and then there are alignment errors within one imagery set, occasionally within resolutions in a set, and usually differing alignments between obviously different imagery sets.
Still, having the imagery is certainly better than not having it.
Discussion
Comment from AndrewBuck on 11 July 2011 at 14:59
Just so that you know, all the major editors support shifting the background imagery by letting you drag it with the mouse to what you think is correct (road from gps traces, etc).
Comment from Tom Layo on 11 July 2011 at 15:25
As above, but press 'space bar' first.
Comment from alimamo on 12 July 2011 at 00:35
Yep. Shifting is a necessity here. Thanks.
Comment from dcp on 12 July 2011 at 08:43
What I do to align the Bing imagery is to load the saved tracks to Josm, (preferably a main twisty road with a lot of tracks). Your eye can then average the tracks and you align the Bing imagery to those averaged tracks. I know it only works when there are a lot of saved tracks to average on so this method of alignment will only work in remote areas.
Comment from PsJp on 14 July 2011 at 11:28
So assuming the satellite image is located correctly and making changes to OSM was a mistake?
I took four GPS readings with two different GPS' gave me four different readings.
How do I know the correct position to adjust the imagery?
Comment from alimamo on 14 July 2011 at 11:58
It could have been a mistake. It does depend on where you are.
The best thing to do is download the GPS traces, turn off the data, and try and line up the traces to the roads. My bike rides usually go on both sides of the road, so I have a trace that will show the center of the road, and I usually have more than one trace per road.
If there are not many traces in your area, find a road that is away from most tall buildings (if possible), set your GPS receiver to record about every 1 - 2 seconds, and just go up and down the road several times. If there is a cross-road, go up and down that road several times too. That way you now have a '+' that you can use to align to the map. Don't be afraid to adjust the ways in OSM when you get more traces and can better average the data.
Also, even if the roads you added are not exactly correct, that is OK. In time you and others can adjust the data to make things better.
Good luck.