On 21 Aug 2009, at 17:13, Chris Hill wrote:
Roger Slevin wrote:
Peter
I can confirm that the Department for Transport would be supportive
of any way in which we (and the local editors who maintain NaPTAN
data as best they can) can get the feedback from OSM contributions
to improve data accuracy. I will be happy to discuss how best this
can be done – but I suggest that you and others on this list are
much better placed to propose a method that works within the
framework of OSM.
Roger
[snip]
I have reported the faults I have found via the professional
service we run for the DfT for the purpose (http://www.itoworld.com/static/naptan
). I suggest that the DfT/Traveline might consider making this
interface available to OSM mapping people to do the same or opening
up a public version.
It will be useful in time to run a comparison between the current
NaPTAN and the current OSM and produce reports of where they are
diverging. We would need the permission of the department to take a
cut of the NaPTAN data before each run but I think they would be
supportive.
Sorry for the last post - finger trouble.
So it seems that feeding back to NaPTAN would be good since they are
interested in these improvements. As such we need to find all of
the differences, including position changes. This still leaves us
with the question: do we amend the naptan: tags or add our own to
show the changes? What did the West Midlands guys do?
Thinking about this.
I believe that we are of the opinion that the naptan tags are useful
but only relevant to the UK and I don't think anyone is suggesting
that an import of data from Portland or Washington DC should use these
NaPTAN tags. So, do we need tags in the real OSM namespace tags for
all the main elements of NaPTAN that we need to use (for example
bearing from naptan:bearing, indicator from naptan:indicator and
local_ref from naptan:ATCO_code?). In some cases these will be copies
of the naptan namespace data for the UK. For other imports it might
using GTFS or other formats might use ia GTFS namespace for the
imported data and then the same tags as for NaPTAN for the main OSM
tags.
If that is the case then we should leave the naptan information alone
and only adjust the OSM tags. The only problem is that some of those
fields are not current populated or even defined in OSM (for example
bearing).
For now I have changing the NaPTAN fields where I consider that they
are wrong because we can spot that sort of thing in an refresh import
of NaPTAN.
For a future 'refresh import' of NaPTAN the rule could be that we
replace the data in the NaPTAN namespace (noting any changes in a log
that is made available to the local community) and then notice where
there are conflicts between OSM changes and official changes within
the tags in the OSM namespace. Where the NapTAN data has changed but
the OSM tags still match the naptan tags then the OSM tags can be
updated, Where the OSM tags are no longer the same as the NaPTAN tags
then that would be a 'conflict' and would need to deal with manually.
If this is what we want then we should get it onto the wiki.
Regards,
Peter
Cheers, Chris
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