[OSM-legal-talk] Mixing ODbL and CC-BY-SA databases

[Frederik Ramm]

Hi,

    here's an interesting one.

Suppose OSM has just changed its license to ODbL. A final CC-BY-SA 
planet has been released, non-relicensed data has been removed from the 
servers, and the project is again humming along nicely (relief!).

Now I would like to make a slippy map overlay where areas are coloured 
red or green or different shades in between according to how much data 
is missing from the current ODbL dataset compared to the old CC-BY-SA 
data set. The idea being, if an area is red, it may be worth going there 
and resurveying the area because edits have been lost.

I wonder if this is possible at all. Behind the scenes, I would have to 
compare the old CC-BY-SA data with the new data set to find out what 
happened. My tiles would be a derived work from the CC-BY-SA data set 
and as such licensed CC-BY-SA, no problem there. However, I would in all 
likelihood be creating an interim database derived from the new ODbL 
data set and the old CC-BY-SA data set. ODbL would require that I 
release that database under ODbL. But CC-BY-SA requires that if I 
release the database it must be under CC-BY-SA exclusively. Thus I 
cannot release the database, thus I cannot publish the tiles.

Right?

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"