OpenStreetMap
After correcting some errors in my neighborhood (removing streets that were planned but never built because the property was sold to a church), I also tweaked the data points, which were all slightly southeast of the satellite image. I notice now that it's a general problem for the Memphis, TN area. Any advice? Is there a way to apply a correction over an entire area, or is something else amiss?
Discussion
Comment from lyx on 19 April 2010 at 22:33
The satellite images are often a bit off the mark as well, so you can't be sure if the map data or the images are in the wrong position. What I usually do is trying to find a few GPS tracks that match roads in the image and use that to move the images into the right position.
Comment from andrewpmk on 19 April 2010 at 22:37
Just realign the roads to match the satellite imagery. There are a couple of GPS traces in the area you are looking at, it is obvious that the satellite imagery is aligned properly in the Memphis area. (Don't forget that GPS can also be inaccurate as well.)
Comment from ToeBee on 20 April 2010 at 00:38
Yeah, I have found the satellite imagery to be spot-on compared to all my GPS traces. All the roads in my area of town were shifted pretty significantly to the northwest in OSM. Several hours of tweaking later, they are no longer! Have you tried playing around with the JOSM editor? I'm thinking it is more likely than POTLATCH to have the ability to select multiple ways at a time and do mass corrections like that.