[Talk-GB] Separation of sources

[Martin - CycleStreets]

If I may offer the view of a user of OSM data rather than a creator.

Patchy areas of OSM cause real difficulties for CycleStreets, not only in 
reputational terms but in terms of debugging. Places where the basic road 
pattern is absent undermine our ability to demonstrate that a UK-wide 
system using open data works everywhere - nor can we even promote the 
system effectively because of this. We get plenty of bug reports that 
clearly arise simply as a result of missing basic road data, never mind the 
subtleties of additional cycle infrastructure (which in other areas of OSM, 
are stunningly good).


I'm not sure I quite understand the objection to tracing over other data 
that OSM can legally and ethically use (though can appreciate David Earl's 
point of view). The fact is that this OS data is "our" data which mostly we 
as taxpayers have paid for already. Why shouldn't we make use of it and 
incorporate it as the basis of a road network that can then be 
incrementally improved, adjusted and built upon, more quickly (unless it is 
not 'good enough' from an accuracy perspective)?

I agree in an ideal world, ground-surveys done from first principles will 
be preferable. But the fact is that there remain areas of the country that 
routing. Wolverhampton and Newcastle for instance are places which we 
certainly would love to see become usable for routing as early as possible.

I agree with other posters that mass, automated imports sound like a recipe 
for disaster, from both a technical and, crucially, a 
volunteer-encouragement perspective. So wouldn't the pragmatic way forward 
be to patch in / trace over data in incomplete areas, so that it forms the 
basic network? Surrounding map features can be augmented on top of that 
more easily on an incremental basis, leading to having the same richness as 
other areas (e.g. Cambridge, which is an amazing level of detail, and which 
forms for us an excellent testing ground for our engine because we know the 
data side is pretty faultless).

Might it not be a best use of volunteer time to be adding really 
interesting map features that other sources do not have, rather than having 
to use this time to get basic streets in place first?

We certainly would love to see (more universally) stuff that other datasets 
don't have, like whether a place is lit or not, but it's going to take a 
while to get to that if basic street patterns still remain to be 
walked/cycled first.


> If people want other sources so much, won’t they encourage the effort to 
> combine the independent sources?

I think that surely underestimates the effort required. Processing one 
massive dataset is bad enough, never mind having to do this for several 
sources and find ways to deal with merging/clashing.

http://www.cyclestreets.net/journey/help/osmconversion/sieve/
shows our current sieving routine (NB Andy's pointed out that there is a 
better way to do this upstream, but we've not had the time to migrate yet.)


OSM is a great project, and I think the head-start of basic road data, 
which can be adjusted and improved on, is something that is needed to get 
towards completion more quickly, creating a superset that will become 
irresistable to people that were previously sceptical about open 
geographical data.


Martin,                     **  CycleStreets - For Cyclists, By Cyclists
Developer, CycleStreets     **  http://www.cyclestreets.net/