[HOT] Helping Japan by tracing

[Alan Mintz]

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 
>and boundary=administrative.
>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>