Campbell Barton ported the OpenStreetMap import script to 2.6 for us !
And it’s now in trunk.
The script loads XML files saved from the OpenStreetMap website (http://www.openstreetmap.org) into Blender (as edges).
This was quite helpful in blocking out the Oude Kerk area for mango (to correctly place the church and the buildings around)
Now, we’re integrating these maps with more detailed infos (necessary for the final models but also for animatic / previz purpose)
The the finer measurements will come from survey or more accurate plans : city planning maps can be very useful in these situations (especially roads height measures)
We haven’t got those yet but we might be able to get all needed data from tracking (Sebastian is testing that on the ground surfaces just now)