[HOT] Helping Japan by tracing
Alan_Mintz+OSM at Earthlink.Net
Tue Mar 15 00:40:04 GMT 2011
At 2011-03-14 13:50, Emilie Laffray wrote:
>the coastline in Japan is coming from the Japanese governement and tends
>to be pretty good. It is the reason why they are both natural=coastline
>MLIT is one of the Japanese ministries which has tons of open Data.
> Some of the data can be pretty old some can be pretty recent. I suspect
> you can alter them if you feel that the imagery represents the ground
> truth, but be aware that some of those forests are huge.
The question is, what scale was the existing data suitable for? If it was
itself traced from 1,000,000:1 maps from 1985, then it may very well
benefit from realignment against imagery, but be concerned if there is a
large (i.e. 50m) consistent error - that would need some digging to know
what's right. If, instead, it was from a GPS/sonar/whatever survey in 2005,
or 1,000:1 imagery, I'd be wary of changing it without accurate control
points to verify the accuracy of the Bing imagery.
Alan Mintz <Alan_Mintz+OSM at Earthlink.net>
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