Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Peter Miller]

On 29 May 2012 16:05, Richard Mann wrote:

> I think Peter was planning on making the ITO boundaries available as a
> traceable layer, but haven't heard anything about this recently.
>

You are right. It should be possibly to use ITO Map tiles in Potlatch and
JOSM, however there seems to be glitch at present which we will take a look
at over the next few days and get back to you on this list.

You will probably also be aware that updates for ITO Map have also pretty
much failed since the planet dumps disappeared at the start of April with
the license change. We had initially understood that planet would be down
for about two week and planned to sit it out, however given the protracted
nature of the changeover we are now working hard on a fix that can be used
with the current files and will get us back to daily updates.


Regards,


Peter



> On Tue, May 29, 2012 at 4:00 PM, Tom Chance  wrote:
>
>> On 29 May 2012 15:44, Colin Smale  wrote:
>>
>>> My questions to the community:
>>> 1) Would a bulk upload of any or all of this data be interesting?
>>>
>>
>> Thanks for raising this, it would be great to get a more complete set of
>> boundaries. In answer to your first question, no, please don't follow a
>> bulk upload approach. I say this for two reasons:
>>
>> 1) Most boundaries follow existing features like roads, rivers, etc. They
>> need to be manually entered as relations sharing nodes with those features.
>> In my experience this is often a nice opportunity to spot other problems
>> with very old features using aerial imagery and GPS tracks, e.g. poor
>> alignment, or complicated junctions that aren't fully modelled for routing.
>> So much better done manually than by dumping a load of new ways into the
>> database.
>>
>> 2) Many boundaries already exist, but are often slightly incorrect, e.g.
>> not sharing nodes with existing features but being a little offset. By
>> doing this manually you can improve these as you go, especially since every
>> boundary shares its properties with one or more other boundaries.
>>
>> The best approach would be to identify which boundaries are missing, put
>> those up in a list and and encourage people to get us to 100%. Perhaps
>> start with counties, then unitaries and districts, then even wards.
>>
>> ITO have a nice map of boundaries that people can use to check up on
>> them, you can see I started to add wards in Southwark:
>> http://www.itoworld.com/map/2
>>
>




>> Regards,
>> Tom
>>
>> --
>> http://tom.acrewoods.net   http://twitter.com/tom_chance
>>
>> ___
>> Talk-GB mailing list
>> Talk-GB@openstreetmap.org
>> http://lists.openstreetmap.org/listinfo/talk-gb
>>
>>
>
> ___
> Talk-GB mailing list
> Talk-GB@openstreetmap.org
> http://lists.openstreetmap.org/listinfo/talk-gb
>
>
___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Tom Hughes]

On 31/05/12 13:37, Colin Smale wrote:


Does OSM have any facility for hosting these files? They are about 500MB
all together, but they compress very nicely.


Sure - just ask for a dev serv account:

http://wiki.openstreetmap.org/wiki/Using_the_dev_server

Tom

--
Tom Hughes (t...@compton.nu)
http://compton.nu/

___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Colin Smale]

I have just refreshed the GPX files. The changes are:
*file names changed - replacing spaces with underscores to minimise 
any possible issues with spaces in filenames
*attribution added - referring back to the OS OpenData source data 
and associated licence
*for admin areas which consist of multiple polygons, each polygon (a 
"trkseg" in the GPX) is marked in the "cmt" (comment) tag as "outer" or 
"inner". I know this can be derived from the data as outer polygons are 
clockwise, but it might save someone time/effort to have this 
immediately available in the GPX.


Does OSM have any facility for hosting these files? They are about 500MB 
all together, but they compress very nicely.


Someone suggested I make a wiki page for this. I will try to do that at 
the weekend.


Colin

On 30/05/2012 00:59, Colin Smale wrote:
Having just taken a look at ogr2osm I think that is probably the best 
way of achieving OSM-data with a view to a bulk import. However there 
are lots of disadvantages and gotcha's on that route as several people 
have pointed out. If we were to take that route there would not be any 
point in going further with the GPX files.


I have prepared a set of GPX files (one per admin area) from the main 
OS shapefiles. What would be the best way to get these into OSM? I 
guess it will be a manual process to split the boundary, create a 
relation, transfer the tags from any existing data, and link 
everything up. Can someone who has experience with such things suggest 
a workflow? Personally I tend to work with Potlatch2, but please let 
us all know if there's a better way. I assume (as someone else already 
suggested) the OS is probably the best source available for this data. 
So any existing admin boundaries (counties/regions etc) will need to 
be adjusted by hand to connect up with the district boundaries from 
this OS dataset.


I am currently uploading the GPX files to the following (temporary) 
location:

http://csmale.home.xs4all.nl/os/boundaryline/

Please let me know if you find any anomalies in these files!

Colin




___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[David Fisher]

Hi all,
I was just wondering whether, beyond the obvious use of having accurate
boundary data in OSM, the Boundary Line data could also be used to align
aerial imagery, particularly at the closest zoom levels?
For instance, I map in South London, close to multiple borough boundaries.
As a test, I downloaded the (more accurate) 2010 data last night and opened
it in JOSM as a layer along with downloaded OSM data and Bing imagery.  In
certain places the Bing imagery shows obvious geometric shapes such as
building outlines or fences/hedges, which it could reasonably assumed that
the boundary would follow (and of course the more you look along the
boundary line, the more features you can use to make the fit).   It seems
to me to be a valid & useful approach, but I just wondered what others
thought?
Thanks,
David.


On Wed, May 30, 2012 at 5:25 PM, Craig Wallace  wrote:

> On 30/05/2012 16:11, Jason Cunningham wrote:
>
>>
>> This suggests the original Boundary Line data is superior, but would
>> need to be compared to 2012 releases to check boundaries have not moved.
>>
>> Does anyone have the original Boundary Line release? and would they be
>> able to make them available?
>>
>
> The previous releases of Boundary Line data are available here:
> http://parlvid.mysociety.org:**81/os/
> http://os.openstreetmap.org/**data/ 
>
>
> __**_
> Talk-GB mailing list
> Talk-GB@openstreetmap.org
> http://lists.openstreetmap.**org/listinfo/talk-gb
>
___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Craig Wallace]

On 30/05/2012 16:11, Jason Cunningham wrote:


This suggests the original Boundary Line data is superior, but would
need to be compared to 2012 releases to check boundaries have not moved.

Does anyone have the original Boundary Line release? and would they be
able to make them available?


The previous releases of Boundary Line data are available here:
http://parlvid.mysociety.org:81/os/
http://os.openstreetmap.org/data/

___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Jason Cunningham]

On 29 May 2012 23:59, Colin Smale  wrote:

>
> I have prepared a set of GPX files (one per admin area) from the main OS
> shapefiles. What would be the best way to get these into OSM?
>

Thanks for doing this. I agree use of the data will require individuals
effortt, so I'd suggest creating a wiki page which people could be updated
to show areas status.

I'd like to raise another issue. I agrree that the OS data is as definitive
as we are going to get, but it looks like the recent OpenData releases have
been "dumbed down". If you compare the original 2010 releases with the
2011/12 releases then the 2010 release appears, in places, far superior.
Only a few weeks ago I unfortunately deleted my original download of the
Boundrary Data, but to show you what I mean I've put the 'VectorMapDistrict
- AdminstrativeArea' shapefile from 2010, and a Boundrary Line 2011, on a
google image (using qgis).
Green = 2010
Red = 2012
http://i227.photobucket.com/albums/dd132/jamicu/VectMapDist_AminBoundary_2010vBoundary-Line2012.jpg

You can see the Boundary Line 2012 has lost a lot of data originaly
available.

This suggests the original Boundary Line data is superior, but would need
to be compared to 2012 releases to check boundaries have not moved.

Does anyone have the original Boundary Line release? and would they be able
to make them available?

Jason
___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Colin Smale]

Having just taken a look at ogr2osm I think that is probably the best 
way of achieving OSM-data with a view to a bulk import. However there 
are lots of disadvantages and gotcha's on that route as several people 
have pointed out. If we were to take that route there would not be any 
point in going further with the GPX files.


I have prepared a set of GPX files (one per admin area) from the main OS 
shapefiles. What would be the best way to get these into OSM? I guess it 
will be a manual process to split the boundary, create a relation, 
transfer the tags from any existing data, and link everything up. Can 
someone who has experience with such things suggest a workflow? 
Personally I tend to work with Potlatch2, but please let us all know if 
there's a better way. I assume (as someone else already suggested) the 
OS is probably the best source available for this data. So any existing 
admin boundaries (counties/regions etc) will need to be adjusted by hand 
to connect up with the district boundaries from this OS dataset.


I am currently uploading the GPX files to the following (temporary) 
location:

http://csmale.home.xs4all.nl/os/boundaryline/

Please let me know if you find any anomalies in these files!

Colin

On 30/05/2012 00:06, Ed Loach wrote:

It should only be attempted by an experienced mapper who is
familiar with
revert and other advanced techniques and can follow the guidelines
on the
wiki. The potential to break something is very great, so I would
question
making converted data available. Any conversion needs to build the
relations
so use something like 'ogr2osm' to create .osm files - a

conversion to

GPX
will not do this.

I'll second this. I used to run a boundary validation routine daily
on the British Isles extract from Geofabrik. I stopped it at the end
of March when I was expecting there to be no new extracts until
after the licence change completed, but this thread had me run it
again today. Previously I was fixing broken boundaries if they
remained broken more than a week (in case people were still working
on them), but towards the end of March decided to wait until the
licence change process was complete as that is likely to break some.

Anyway, at the end of March there were 16 admin boundaries listed
here:
http://www.loach.me.uk/osm/boundaries/
(includes false positives at admin levels 2 and 4 as not all
required ways are in the extract). As you can see this has roughly
tripled in the last two months. Whether this is remapping stuff that
has caused it or not I don't know.

Ed

PS: Note in some cases the "break" might just be an inconsistent use
of roles on member ways.


___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb



___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Ed Loach]

I mentioned:

> http://www.loach.me.uk/osm/boundaries/

You might notice on the National Parks page I say that the National
England boundaries weren't compatible. Since I designed the page
they have switched to OGL. I might get around to updating the pages
at some point, and also check all source links are still current.

Ed


___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Ed Loach]

> It should only be attempted by an experienced mapper who is
> familiar with
> revert and other advanced techniques and can follow the guidelines
> on the
> wiki. The potential to break something is very great, so I would
> question
> making converted data available. Any conversion needs to build the
> relations
> so use something like 'ogr2osm' to create .osm files - a
conversion to
> GPX
> will not do this.

I'll second this. I used to run a boundary validation routine daily
on the British Isles extract from Geofabrik. I stopped it at the end
of March when I was expecting there to be no new extracts until
after the licence change completed, but this thread had me run it
again today. Previously I was fixing broken boundaries if they
remained broken more than a week (in case people were still working
on them), but towards the end of March decided to wait until the
licence change process was complete as that is likely to break some.

Anyway, at the end of March there were 16 admin boundaries listed
here:
http://www.loach.me.uk/osm/boundaries/
(includes false positives at admin levels 2 and 4 as not all
required ways are in the extract). As you can see this has roughly
tripled in the last two months. Whether this is remapping stuff that
has caused it or not I don't know.

Ed

PS: Note in some cases the "break" might just be an inconsistent use
of roles on member ways.


___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Steve Brook]

Hi

Having done the import for the all of the Worcestershire parishes I will add
my views:

It should only be attempted by an experienced mapper who is familiar with
revert and other advanced techniques and can follow the guidelines on the
wiki. The potential to break something is very great, so I would question
making converted data available. Any conversion needs to build the relations
so use something like 'ogr2osm' to create .osm files - a conversion to GPX
will not do this.
Adding data to the map should not be done as a bulk import as there is a lot
of existing data - some imported and some traced from old map sources. Any
data you import needs to be integrated with existing data. Every boundary
will be shared between at least 2 relations and often many more.

The 'ogr2osm' conversion produced way segments that had a common shared
boundary with another parishes and also produced all the parish level
relations. I then just had to give them the right tags - it's much better to
get them right in the editor before upload than to have to correct them
later. Where parish boundaries were also district, county or region
boundaries I elevated the admin level before the import as it made the
filtering during the subsequent tidy up process easier. I also created
temporary relations for the county level boundaries before import to assist
with the later tidy up stage. Some lines on the perimeter of my data needed
to be cut where at the 3 county intersections. To do this I need to go back
to the original data to find the correct node to use. This was the main
reason why I chose to do the whole county in one go to minimise subsequent
work at the edges of the area I worked on.

I was lucky in Worcestershire as very few parish boundaries were present and
they were fairly easy to sort out by deleting those that only had boundary
tags and removing boundary tags from shared ways. 
I made a note of the numbers of all the existing boundary relations in the
area before I started work so I could update them with my new data. Where my
import matched some one else's import of the district boundary data I
usually kept the earlier work but split it into parish segments. The work
took many evening and late nights to complete.

If anyone wants more specific advice I am willing to provide it - just send
me an email.

Steve



___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Chris Hill]

  
  
On 29/05/12 20:16, Tom Chance wrote:

  On 29 May 2012 18:52, Chris Hill 
wrote:

  My question is: how do you know the boundary aligns with an
  existing object?
  
  
  Aha! A very good point.
  
  I suppose in my case because I've been actively involved in
  canvassing for a political party for years in the area, I know
  which wards people on different streets live on both from maps
  I've seen at some point, the electoral register, talking to
  colleagues who are familiar with wards and from going round and
  talking to people on the doorstep who know which ward they're in.
  With that all in my head and a clear overlap between boundaries
  and features in my local area it's pretty easy to get the wards
  right. Perhaps that's not really local knowledge and I should
  remove the data?


That sounds like local knowledge to me, but your detailed knowledge
is local to you, not shared by many other people contributing to OSM
and can't be used by everyone to know when a road and boundary line
up.
 

  
  It does raise the question of how worthwhile it is to enter
  boundaries where precision is important (e.g. between houses but
  not so much in the middle of a rural field) if we have no
  copyright-free way of determining exactly where boundaries are.
  


We have the boundary data provided in OS Open data, which is where
the thread started. It is as close to definitive as we are ever
likely to get.
-- 
Cheers, Chris
user: chillly

  


___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Tom Chance]

On 29 May 2012 18:52, Chris Hill  wrote:

> My question is: how do you know the boundary aligns with an existing
> object?


Aha! A very good point.

I suppose in my case because I've been actively involved in canvassing for
a political party for years in the area, I know which wards people on
different streets live on both from maps I've seen at some point, the
electoral register, talking to colleagues who are familiar with wards and
from going round and talking to people on the doorstep who know which ward
they're in. With that all in my head and a clear overlap between boundaries
and features in my local area it's pretty easy to get the wards right.
Perhaps that's not really local knowledge and I should remove the data?

It does raise the question of how worthwhile it is to enter boundaries
where precision is important (e.g. between houses but not so much in the
middle of a rural field) if we have no copyright-free way of determining
exactly where boundaries are.

Regards,
Tom

-- 
http://tom.acrewoods.net   http://twitter.com/tom_chance
___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Richard Fairhurst]

Colin Smale wrote:
> I realise I probably caused some confusion by using the words 
> "bulk upload" when I really intended "bulk import". Sorry about 
> that... I was thinking about a way of getting all the data into 
> OSM without having to do too much manual work.

That won't really fly, I'm afraid - most of the boundaries are already in
there (albeit in imperfect form), so if you import them you'll have
duplicate data. Better to use the enthusiasm of the community to bring the
data in properly.

> But if people would prefer me to dump the individual 
> GPX files on a server somewhere so people can grab their local 
> councils and get them "by hand" into OSM, that's fine by me as well.

Yes please!

cheers
Richard



--
View this message in context: 
http://gis.19327.n5.nabble.com/Admin-Boundaries-and-OS-OpenData-BoundaryLine-tp5710573p5710619.html
Sent from the Great Britain mailing list archive at Nabble.com.

___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Chris Hill]

  
  
On 29/05/12 18:10, Tom Chance wrote:

  On 29 May 2012 17:19, Chris Hill 
wrote:

  
They need to be
  manually entered as relations sharing nodes with those
  features. 

  
  I would say that sharing nodes can lead to problems.
  Boundaries that get imported or manually traced from OS data
  often have no visible reference on the ground. If you share
  nodes with something else, when someone aligns that something
  else to aerial imagery, or a GPS trace or whatever, the
  boundary (which was probably right) gets moved too. Why do
  nodes of one object need to be shared when they are quite
  different objects?
  
  
  This probably varies according to a number of factors, but where
  boundaries are just abstract information coterminous with physical
  features it makes sense to me that the objects in OSM share nodes.
  Many boundaries in urban areas could just be relations containing
  lots of roads.
  


My question is: how do you know the boundary aligns with an existing
object? If they align, what evidence on the ground do you have for
that? How do you *know* that a road, stream or whatever aligns with
the boundary, other than using other sources such as complete
(copyright) OS maps?

I would say import or draw the boundary based on the OS Open data as
a separate entity from anything else. 

Take the example of someone moving a road but not also
  moving the boundary. That introduces an inaccuracy right away. 

How do you know that? What rule is there that says a boundary must
follow a road? Why, if the OS Boundary data has been used, would you
want to move a boundary unless an administrative change has been
made?

They could also move both but not bother to get the
  locations exactly right, say by making the gap between them
  larger, getting a kink in the wrong place, or not having them
  exactly coterminous. Perhaps they aren't all that interested in
  boundaries. But then along another person comes to check if a
  house is in this or what ward and they're misled. I prefer to have
  the boundaries share nodes so that people are forced to move
  boundaries with roads/streams/etc. and forced to break them apart
  if they really aren't coterminous.


I think some areas such as some landuse can be described as
coterminous and might benefit from sharing nodes. Sharing nodes
between disparate object types causes more trouble than it is worth
IMHO. I don't see how a road and a boundary can be described as
coterminous since there is no evidence of it from a source we can
use.  


  
  To my mind in these cases boundaries should be treated the same as
  routes.


I don't understand that comparison.


  Of course if you don't know that a stream and a boundary are
  supposed to be related and you go and share nodes because they
  happen to be in roughly the same place, then moving the stream to
  align with a GPS trace obviously shouldn't move the boundary so
  you introduce problems.


That's my point, how would you know that a boundary is 'supposed' to
be related to anything else? Are  boundaries ever anything more than
arbitrary? They don't exist on the ground, even the boards saying
"Welcome to My Town" are not always placed on the boundary because
of traffic sign placement rules, indeed, most parish boundaries are
not marked, the village name sign is no where near the parish
boundary.

People will do as they think best, and I'm sure some boundaries will
end up with shared nodes - I just don't see the benefit nor the
justification and I do see problems. 
-- 
Cheers, Chris
user: chillly

  


___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Tom Chance]

On 29 May 2012 17:19, Chris Hill  wrote:

> They need to be manually entered as relations sharing nodes with those
>> features.
>>
> I would say that sharing nodes can lead to problems. Boundaries that get
> imported or manually traced from OS data often have no visible reference on
> the ground. If you share nodes with something else, when someone aligns
> that something else to aerial imagery, or a GPS trace or whatever, the
> boundary (which was probably right) gets moved too. Why do nodes of one
> object need to be shared when they are quite different objects?


This probably varies according to a number of factors, but where boundaries
are just abstract information coterminous with physical features it makes
sense to me that the objects in OSM share nodes. Many boundaries in urban
areas could just be relations containing lots of roads.

Take the example of someone moving a road but not also moving the boundary.
That introduces an inaccuracy right away. They could also move both but not
bother to get the locations exactly right, say by making the gap between
them larger, getting a kink in the wrong place, or not having them exactly
coterminous. Perhaps they aren't all that interested in boundaries. But
then along another person comes to check if a house is in this or what ward
and they're misled. I prefer to have the boundaries share nodes so that
people are forced to move boundaries with roads/streams/etc. and forced to
break them apart if they really aren't coterminous.

To my mind in these cases boundaries should be treated the same as routes.

Of course if you don't know that a stream and a boundary are supposed to be
related and you go and share nodes because they happen to be in roughly the
same place, then moving the stream to align with a GPS trace obviously
shouldn't move the boundary so you introduce problems.

Regards,
Tom



-- 
http://tom.acrewoods.net   http://twitter.com/tom_chance
___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[wool...@hotmail.com]

I've been doing a lot of the boundaries in Devon and Somerset, and a lot of the 
boundaries seem to use streams and rivers.  I therefore use the Centre point of 
larger rivers.

I've also come across ox bow lakes and such which the boundary does still 
follow.

Jason  (unieagle)

Connected by MOTOBLUR™

-Original message-
From: SomeoneElse 
To: talk-gb@openstreetmap.org
Sent: Tuesday, 29 May 2012 17:39:03 GMT+01:00
Subject: Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

Tom Chance wrote:
> 1) Most boundaries follow existing features like roads, rivers, etc.

That raises an interesting question - how is the boundary actually defined?  Is 
it defined as "the boundary between X and Y is the middle of the river Z", or 
has someone plotted a series of points P corresponding to the _current_ course 
of the river and said "the boundary between X and Y is P"?  There are lots of 
places where boundaries (as shown via OS_OpenData_StreetView) don't quite match 
rivers any more - have a look up the River Dove from Ashbourne for an example.

If the latter, then clearly the boundary shouldn't share nodes with e.g. rivers.

Cheers,
Andy


___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb
___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[SomeoneElse]

Tom Chance wrote:

1) Most boundaries follow existing features like roads, rivers, etc.


That raises an interesting question - how is the boundary actually 
defined?  Is it defined as "the boundary between X and Y is the middle 
of the river Z", or has someone plotted a series of points P 
corresponding to the _current_ course of the river and said "the 
boundary between X and Y is P"?  There are lots of places where 
boundaries (as shown via OS_OpenData_StreetView) don't quite match 
rivers any more - have a look up the River Dove from Ashbourne for an 
example.


If the latter, then clearly the boundary shouldn't share nodes with e.g. 
rivers.


Cheers,
Andy


___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Ed Loach]

Colin wrote:

> I have uploaded an example GPX to OSM with the boundary of
> Sevenoaks DC
> in Kent. If anybody is interested in taking a look, you can
download
> it
> here (with a bit of luck):
> 
> http://www.openstreetmap.org/trace/1242073/data

If people want to create their own .osm versions of whichever
boundaries, the notes I made when correcting broken boundaries are
here:
http://wiki.openstreetmap.org/wiki/User:EdLoach#Correcting_the_bound
aries

Ed


___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Colin Smale]

Hi again,

I realise I probably caused some confusion by using the words "bulk 
upload" when I really intended "bulk import". Sorry about that... I was 
thinking about a way of getting all the data into OSM without having to 
do too much manual work. But if people would prefer me to dump the 
individual GPX files on a server somewhere so people can grab their 
local councils and get them "by hand" into OSM, that's fine by me as well.


I have uploaded an example GPX to OSM with the boundary of Sevenoaks DC 
in Kent. If anybody is interested in taking a look, you can download it 
here (with a bit of luck):


http://www.openstreetmap.org/trace/1242073/data

Colin



___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Chris Hill]

On 29/05/12 16:00, Tom Chance wrote:
 Most boundaries follow existing features like roads, rivers, etc. 
Not always by any means. Many urban boundaries follow roads, but many 
rural ones run alongside roads and have little jinks in them where they 
cross to the other side of the road. This allows a stretch of road to be 
firmly the responsibility of one administration, not shared. Many 
boundaries follow an old course of a stream, when the stream moved the 
boundary did not.
They need to be manually entered as relations sharing nodes with those 
features. 
I would say that sharing nodes can lead to problems. Boundaries that get 
imported or manually traced from OS data often have no visible reference 
on the ground. If you share nodes with something else, when someone 
aligns that something else to aerial imagery, or a GPS trace or 
whatever, the boundary (which was probably right) gets moved too. Why do 
nodes of one object need to be shared when they are quite different 
objects?
In my experience this is often a nice opportunity to spot other 
problems with very old features using aerial imagery and GPS tracks, 
e.g. poor alignment, or complicated junctions that aren't fully 
modelled for routing. So much better done manually than by dumping a 
load of new ways into the database.
I agree that manual scrutiny is vital. Local knowledge and control is 
also important. Documenting the existing practice would help too.


2) Many boundaries already exist, but are often slightly incorrect, 
e.g. not sharing nodes with existing features but being a little offset.

That offset might be right. See above.

[...]

--
Cheers, Chris
user: chillly


___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Tom Chance]

On 29 May 2012 16:03, Richard Fairhurst  wrote:

> Colin Smale wrote:
> > My questions to the community:
> > 1) Would a bulk upload of any or all of this data be interesting?
>
> I think uploading the files somewhere for people to use would certainly be
> interesting, yes. You could find some webspace and upload (say)
> leicestershire.osm and cumbria.osm and so on.


Oh, sorry Colin, I misread your suggestion. This approach sounds very
useful, thanks.

Tom

-- 
http://tom.acrewoods.net   http://twitter.com/tom_chance
___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Richard Mann]

I think Peter was planning on making the ITO boundaries available as a
traceable layer, but haven't heard anything about this recently.

On Tue, May 29, 2012 at 4:00 PM, Tom Chance  wrote:

> On 29 May 2012 15:44, Colin Smale  wrote:
>
>> My questions to the community:
>> 1) Would a bulk upload of any or all of this data be interesting?
>>
>
> Thanks for raising this, it would be great to get a more complete set of
> boundaries. In answer to your first question, no, please don't follow a
> bulk upload approach. I say this for two reasons:
>
> 1) Most boundaries follow existing features like roads, rivers, etc. They
> need to be manually entered as relations sharing nodes with those features.
> In my experience this is often a nice opportunity to spot other problems
> with very old features using aerial imagery and GPS tracks, e.g. poor
> alignment, or complicated junctions that aren't fully modelled for routing.
> So much better done manually than by dumping a load of new ways into the
> database.
>
> 2) Many boundaries already exist, but are often slightly incorrect, e.g.
> not sharing nodes with existing features but being a little offset. By
> doing this manually you can improve these as you go, especially since every
> boundary shares its properties with one or more other boundaries.
>
> The best approach would be to identify which boundaries are missing, put
> those up in a list and and encourage people to get us to 100%. Perhaps
> start with counties, then unitaries and districts, then even wards.
>
> ITO have a nice map of boundaries that people can use to check up on them,
> you can see I started to add wards in Southwark:
> http://www.itoworld.com/map/2
>
> Regards,
> Tom
>
> --
> http://tom.acrewoods.net   http://twitter.com/tom_chance
>
> ___
> Talk-GB mailing list
> Talk-GB@openstreetmap.org
> http://lists.openstreetmap.org/listinfo/talk-gb
>
>
___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Richard Fairhurst]

Colin Smale wrote:
> My questions to the community:
> 1) Would a bulk upload of any or all of this data be interesting?

I think uploading the files somewhere for people to use would certainly be
interesting, yes. You could find some webspace and upload (say)
leicestershire.osm and cumbria.osm and so on.

Because so much boundary data (of varying accuracy) is already in OSM,
updating the geometries using OS OpenData would be by necessity a manual
task - which is as it should be. But having the data easily available is the
first step.

With P2, either .gpx or .osm is fine. One file per admin unit would be
better than one 300Mb file... the latter is almost certain to boggle the
amount of data you can load in-browser!

cheers
Richard



--
View this message in context: 
http://gis.19327.n5.nabble.com/Admin-Boundaries-and-OS-OpenData-BoundaryLine-tp5710573p5710577.html
Sent from the Great Britain mailing list archive at Nabble.com.

___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

Re: [Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Tom Chance]

On 29 May 2012 15:44, Colin Smale  wrote:

> My questions to the community:
> 1) Would a bulk upload of any or all of this data be interesting?
>

Thanks for raising this, it would be great to get a more complete set of
boundaries. In answer to your first question, no, please don't follow a
bulk upload approach. I say this for two reasons:

1) Most boundaries follow existing features like roads, rivers, etc. They
need to be manually entered as relations sharing nodes with those features.
In my experience this is often a nice opportunity to spot other problems
with very old features using aerial imagery and GPS tracks, e.g. poor
alignment, or complicated junctions that aren't fully modelled for routing.
So much better done manually than by dumping a load of new ways into the
database.

2) Many boundaries already exist, but are often slightly incorrect, e.g.
not sharing nodes with existing features but being a little offset. By
doing this manually you can improve these as you go, especially since every
boundary shares its properties with one or more other boundaries.

The best approach would be to identify which boundaries are missing, put
those up in a list and and encourage people to get us to 100%. Perhaps
start with counties, then unitaries and districts, then even wards.

ITO have a nice map of boundaries that people can use to check up on them,
you can see I started to add wards in Southwark:
http://www.itoworld.com/map/2

Regards,
Tom

-- 
http://tom.acrewoods.net   http://twitter.com/tom_chance
___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb

[Talk-GB] Admin Boundaries and OS OpenData BoundaryLine

[Colin Smale]

Hi,

It seems that the UK administrative boundaries in OSM are rather 
incomplete. I'm looking for advice about the possibility of doing a bulk 
upload of the OS BoundaryLine data for counties, districts and unitaries.


I have conquered the projection issues with the downloaded shapefiles 
and I can now produce GPX files from the OS data, which look good to my 
eye in Google Earth and Potlatch, aligning very neatly to the natural 
boundary features. To do this I have written a program in VB.NET which 
uses MapWindow GIS for the shapefile loading and the reprojection. It's 
not fully ready yet - I still need to add the metadata to the tracks 
from the shape attributes.


My questions to the community:
1) Would a bulk upload of any or all of this data be interesting?
2) As I have no experience of performing bulk uploads myself, how would 
that actually work? Is GPX a good starting point, or should I be looking 
to produce .osm format?
3) This data is very verbose (lots and lots of points). To what extent 
should simplification be considered, using Douglas-Puecker or similar?


I can make a big GPX available (about 300MB), or a GPX per admin unit. 
Then they will need uploading as traces, converting to ways, splitting 
into parts and recombining into relations. At present each "entity" is a 
polygon (actually a GPX track which ends where it started). Should I 
consider identifying common boundaries and splitting the polygon into 
parts and making the "entities" into relations? Obviously this won't 
work with GPX format, so .osm would be required for this. There are many 
"entities" with enclaves/exclaves so these would require multipolygon 
relations. I have not looked at how these turn out in the GPX. I 
probably need to watch for the direction (clockwise/anticlockwise).


Would anybody have any advice about how I could take this further?

Regards,
Colin

___
Talk-GB mailing list
Talk-GB@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk-gb