On 11/12/11 11:26, Borbus wrote:
First of all, when I say import I mean a manual import: reprojection of
OS shapefiles, conversion to OSM data and careful processing in JOSM
before uploading.
I'd really like to get all the water features from OS into OSM. It's
very useful data and also makes maps prettier. It's quite a laborious
task, though, as the data requires manual creation of multipolygons and
of course merging with any water features we already have.
I have already done a small amount here:
http://www.openstreetmap.org/?lat=52.6006&lon=1.6362&zoom=13&layers=M
Although I have not joined together all gaps, just some gaps where a way
crosses it and it is obviously a conduit.
Now I have split the Vectormap square TG into smaller chunks which I
plan to process one by one and upload. The amount of data in just this
square is quite large, but it's still probably less than half of Norfolk.
Have any large scale imports from this dataset already been done?
Do people think this is a good idea? Any suggestions regarding the process?
Happy mapping,
Borbus.
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Plenty of those responding seem to be saying "good idea in principle,
but huge amount of effort required". Just to add my voice to this line
and to provide a bit of experience.
Before I left the Environment Agency about three years ago I was
involved in a project to do something a bit like this. The source data
was different (Master Map) and the ambition for output was in some ways
more modest (centreline only required), but it had to be (a) as
comprehensive as possible including all the MasterMap features and (b)
had to be topologically complete with no gaps etc. A lot of money was
spent on the project and we were constantly having to re-draft budgets
and time-scales as it became clear just how big a job this was going to
be. The local knowledge (an important requirement as emphasised by many
here) was provided by Agency Area staff who are familiar with the river
network in their area.
The project was completed after I left, as a result of which the Agency
does now have a good centreline river network (described along with
other Agency datasets here
<http://publications.environment-agency.gov.uk/PDF/GEHO1210BTHN-E-E.pdf>
) but this took several years and considerable internal and consultancy
human resource to compile. I think that at least some aspects of the
detailed methodology used have been published. I will look into this and
if I find it, will post links to this list.
I know that we have an army of enthusiastic volunteers, which can to
some extent substitute for money and paid GIS technicians, but to be
really comprehensive in this type of mapping requires access to many
miles of water features which run through private land and cannot
therefore be ground-truthed with the GPS-in-my-hand methodology.
In my local area (North East Wales) I have contributed to OSM data on
roads, cycleways, footpaths and boundaries. I am not sure whether I
would feel able to systematically improve much on the water features
which I see in current OSM data - minor amendments in some easily
accessible areas would be the best I could do. I would not feel
comfortable importing features from OS Vector data which I would never
be able to get around to seeing on the ground.
Bogus Zaba
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