[Talk-GB] How to work with Government Open Data (e.g. Boundaries, Rights of Way)

[Rob Nickerson]

Hi All,

As the public sector release spatial data in an open licence we may end up
with a few potentially conflicting data sources (Bing, Ground Survey,
Government Shapefiles). I would like hear peoples opinions on this. I will
use the Rights of Way data Hampshire CC recently released, however I am
interested in answers regarding the OS Boundary data as this is harder to
verify on the ground.

Remember that the digitised version is NOT the definitive map (although
this is only for legal purposes) and the paper definitive map shows things
like hedgerows so you get not just the geo coordinates but also the context
(e.g. cross 2 fields cutting through gap in hedgerow). Finally Hampshire's
data is only as good as Ordnance Surveys maps of the countryside - likely
to be low priority and could be quite old.


Question: What to do in the following examples?

1. Hampshire marked footpath and OSM footpath run very close to each other
(deviating by only a few meters max). No obvious marking on Bing Aerial

2. As with 1, but Bing Aerial shows clear path (neither OSM or Hampshire
line up with this path perfectly).

3. OSM path crosses diagonally over a field (roughly following the path
visible on Bing). Hampshire's data indicates a kink in the route so that in
the middle of the field the gap reaches about 20-30 meters.

4. OSM path crosses over 2 fields (following Bing path and cutting through
a gap in hedgerow). Path is a straight line at an angle 'x' from the road.
Hampshire's data shows the path runs straight, but at angle 'y'. Max
deviation 50m. What about a smaller deviation of only 15m?

5. As 4 above but the Hampshire path appears to cross the hedgerow where
there is no visible gap on Bings imagery.

6. Hampshire have a path marked that is not in OSM. Bing shows there is
something there.

7. As 6 but no marking on Bing. No obvious obstructions

8. As 7 but there is an potential obstruction (e.g. woodland with no clear
path - although this would be hard to see on Bing)

9. As 8 but there is an obvious obstruction (e.g. building).


Answers all welcome. I am interested in how many of these should be sent
back to Hampshire CC.

RobJN

p.s. I guess some of these are the same as the GPS vs Bing arguement, but
with the addition that the government data is "official".
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