[Talk-GB] Offsets between OS and OSM data (was Building with mapseg)

[Tim François]

> On a side note, has anybody noticed a consistent tendency
> for existing
> independently surveyed roads to be offset northwards (by
> around 5-10
> metres) from the OS data (vectormap and streetview)? I've
> seen various
> cases of existing roads being edited to be consistent with
> OS data,
> but I'm not convinced this is a good idea since the problem
> seems to
> be consistent in one direction.

Glad I'm not the only one. Here in the SW I see the same offsets, although I find the VectorDistrict data to be more like the GPS surveyed data. This means that the StreetView tiles do not match up with the VectorDistrict either: I've been importing some rivers and reservoirs from the VectorDistrict data (namely the River Chew and Chew Valley Lake) and I've found that the polygons seem to be shifted compared to the equivalent positions in StreetView by about 10 metres.

I guess this is an expected artifact of the reprojection methods?

Tim