At 2012-06-07 16:39, Mike N wrote:
Using way id 13292685 : http://www.openstreetmap.org/browse/way/13292685
, I looked at the edits. In this case, some nodes were moved, presumably
to align with the aerial imagery. I couldn't find any GPS tracks in the
immediate area to confirm the aerial alignment. The node I looked at
was moved at least 10 meters.
...
A fast preemptive remap for nodes set for redaction-move would be to
just move the node to align with current Bing aerial. Note that the
Bing aerial alignment might not be perfect - try to find some GPS tracks
in the area to see how close it is. There should be some tracks on the
nearest interstate.
This is a non-issue in southern CA. I've done enough calibration against
high-accuracy benchmarks in the area to believe that Bing imagery is
uniformly within 2m of true. OTOH, GPS tracks, especially from an antenna
inside a moving vehicle, are much less accurate than that.
So, the redaction bot will not completely destroy those areas. If no
one has touched the road alignment since his work, it will just revert
back to the original TIGER upload coordinates. All that is required
after the redaction bot will be to nudge the nodes to the location where
they belong.
10m is a big shift. If the errors were that big in this area, I would bet
that if you looked at the original TIGER05 import, it would look like a
toddlers scrawl compared to the look of the map now. I've seen untouched
areas before that were that bad, so I know what it looks like. "All that is
required" will be a huge amount of work to re-align thousands of ways. It
seems far easier to look at them, compare against the imagery, and
pronounce them accurate, and I'd like to get a real legal opinion from
someone involved with the licensing on whether the latter approach would be
sufficient. Can we do that?
--
Alan Mintz <[email protected]>
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