Re: [Talk-GB] building shapes from OS Street View, with code

[Steve Doerr]

From: "Steve Doerr" 
Sent: Sunday, May 30, 2010 3:08 PM

> Looking forward to testing this, but having some problems with the
> prerequisites. I've installed this 'Python' thing (version 2.6) and the
> shapely library, but the NumPy install is failing with a message 'Python
> version 2.6 required, which was not found in the registry'. I'm guessing
> that it may be because NumPy is a 32-bit build (I downloaded it from
> )
> whereas Python is 64-bit.
>
> So, do I reinstall Python as 32-bit, or is there a 64-bit version of NumPy
> around?

With Tim's help, I was able to locate and install 64-bit versions of 
everything.

With an adapted version of the command given in the README file, I have been 
able to process the TQ67SW tile to produce a 4.75MB .osm file. I haven't 
loaded it into JOSM yet, but I'm looking forward to seeing the results.

It took a little over 7 hours to run, by the way.

-- 
Steve
 



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Re: [Talk-GB] building shapes from OS Street View, with code

[Steve Doerr]

From: "TimSC" 
Sent: Friday, May 28, 2010 10:11 AM

> The python code is here (with a readme file):
> http://timsc.dev.openstreetmap.org/dev/mapseg0.1.tar.gz

Looking forward to testing this, but having some problems with the
prerequisites. I've installed this 'Python' thing (version 2.6) and the
shapely library, but the NumPy install is failing with a message 'Python
version 2.6 required, which was not found in the registry'. I'm guessing
that it may be because NumPy is a 32-bit build (I downloaded it from
)
whereas Python is 64-bit.

So, do I reinstall Python as 32-bit, or is there a 64-bit version of NumPy
around?

Grateful for any help.

-- 
Steve 



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Re: [Talk-GB] building shapes from OS Street View, with code

[Tim François]

Thanks for that - I don't use Potlatch, but the amazing array of shortcuts for 
everything astounds me every time: some good work by the author!

--- On Fri, 28/5/10, Graham Stewart  wrote:

From: Graham Stewart 
Subject: Re: [Talk-GB] building shapes from OS Street View, with code
To: "Tim François" , "OpenStreetMap TalkGB" 

Date: Friday, 28 May, 2010, 11:54


Tim,
 
In Potlatch you can also use 'r' or 'Shift-R' to repeat the tags from the last 
way you had selected.
See http://wiki.openstreetmap.org/wiki/Potlatch/Keyboard_shortcuts
 
GrahamS
 
 


On Fri, 28 May 2010 10:39 +, "Tim François"  wrote:




...he scares me



Only joking! I had come across a few of the non-underscored 
versions a few days ago, and was wondering why they were formatted like that. 
Now I know!!



Also, today I learned you can do ctrl+shift+V to copy tags between 
ways/nodes - I've wasted large portions of my life doing this manually! Every 
day's a school day...



*goes off to try and find a page with more neat time saving 
tricks...* 









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Re: [Talk-GB] building shapes from OS Street View, with code

[Graham Stewart]

Tim,

In Potlatch you can also use 'r' or 'Shift-R' to repeat the tags
from the last way you had selected.
See
[1]http://wiki.openstreetmap.org/wiki/Potlatch/Keyboard_shortcuts

GrahamS


On Fri, 28 May 2010 10:39 +, "Tim François"
 wrote:

  ...he scares me
  Only joking! I had come across a few of the non-underscored
  versions a few days ago, and was wondering why they were
  formatted like that. Now I know!!
  Also, today I learned you can do ctrl+shift+V to copy tags
  between ways/nodes - I've wasted large portions of my life doing
  this manually! Every day's a school day...
  *goes off to try and find a page with more neat time saving
  tricks...*

References

1. http://wiki.openstreetmap.org/wiki/Potlatch/Keyboard_shortcuts
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Re: [Talk-GB] building shapes from OS Street View, with code

[Tim François]

...he scares me

Only joking! I had come across a few of the non-underscored versions a few days 
ago, and was wondering why they were formatted like that. Now I know!!

Also, today I learned you can do ctrl+shift+V to copy tags between ways/nodes - 
I've wasted large portions of my life doing this manually! Every day's a school 
day...

*goes off to try and find a page with more neat time saving tricks...*

--- On Fri, 28/5/10, Jerry Clough - OSM  wrote:

From: Jerry Clough - OSM 
Subject: Re: [Talk-GB] building shapes from OS Street View, with code
To: talk-gb@openstreetmap.org
Date: Friday, 28 May, 2010, 11:31

Ask Richard F!

From: Tim François 
To: talk-gb@openstreetmap.org; Jerry Clough - OSM 
Sent: Fri, 28 May, 2010 11:20:10
Subject: Re: [Talk-GB] building shapes from OS Street View, with code

...any reason why no underscores with Potlatch?

--- On Fri, 28/5/10, Jerry Clough - OSM  wrote:

From: Jerry Clough - OSM 
Subject: Re: [Talk-GB] building shapes from OS Street View, with code
To: talk-gb@openstreetmap.org
Date: Friday, 28 May, 2010, 11:15

Potlatch's "b" option will place "source=OS OpenData StreetView" (note no 
underscores) if you have OS SV in the background. I use this as I prefer 1 
keystroke to 20 or so.

From: TimSC 
To: talk-gb@openstreetmap.org
Sent: Fri, 28 May, 2010 10:57:25
Subject: [Talk-GB] building shapes from OS Street View, with code

Ah yes, the recommended tag is
 good. I didn't notice one had been chosen 
(but it is a bit long for my taste). So use 
"source=OS_OpenData_StreetView" for verified buildings. And I will 
probably change to "source=Auto_OS_OpenData_StreetView" for automatic 
tracing in the code.

TimSC


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Re: [Talk-GB] building shapes from OS Street View, with code

[Jerry Clough - OSM]

Ask Richard F!





From: Tim François 
To: talk-gb@openstreetmap.org; Jerry Clough - OSM 
Sent: Fri, 28 May, 2010 11:20:10
Subject: Re: [Talk-GB] building shapes from OS Street View, with code


...any reason why no underscores with Potlatch?

--- On Fri, 28/5/10, Jerry Clough - OSM  wrote:


>From: Jerry Clough - OSM 
>Subject: Re: [Talk-GB] building shapes from OS Street View, with code
>To: talk-gb@openstreetmap.org
>Date: Friday, 28 May, 2010, 11:15
>
>
>Potlatch's "b" option will place "source=OS OpenData StreetView" (note no 
>underscores) if you have OS SV in the background. I use this as I prefer 1 
>keystroke to 20 or so.
>
>
>
>

From: TimSC 
>To: talk-gb@openstreetmap.org
>Sent: Fri, 28 May, 2010 10:57:25
>Subject: [Talk-GB] building shapes from OS Street View, with code
>
>Ah yes, the recommended tag is
> good. I didn't notice one had been chosen 
>(but it is a bit long for my taste). So use 
>"source=OS_OpenData_StreetView" for verified buildings. And I will 
>probably change to "source=Auto_OS_OpenData_StreetView" for automatic 
>tracing in the code.
>
>TimSC
>
>
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>
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Re: [Talk-GB] building shapes from OS Street View, with code

[Ed Loach]

> Ah yes, the recommended tag is good. I didn't notice one had
> been chosen
> (but it is a bit long for my taste). So use
> "source=OS_OpenData_StreetView" for verified buildings. 

A bit long yes, and probably not what Potlatch uses if you press 'b'
when the Streetview background is selected (I see this has been
covered in later posts - it uses the description for the selected
background as shown in the dropdown list IIRC), but autocomplete in
Potlatch and JOSM tend to pick it up once you've done one or two
(though when tracing lots of buildings I tag the first manually in
JOSM and then copy tags with Ctrl-Shift-V to all the rest). Oh, and
I was using source:building=OS_OpenData_StreetView for the original
outline, as whether I've then terraced that building into multiple
properties and/or added house numbers, shop names, or whatever are
all down to surveyed information, so I wanted to be clear.
(Similarly if I've added a road from GPS trace but name from SV I
add it as source:name). I'm not entirely happy where I've surveyed a
traced building and changed it from building=yes to building=garages
about not showing that "garages" is from survey, but wasn't sure how
to handle that. Presumably any non-yes value must be from a survey
(it is around here, at least - here being http://osm.org/go/0EHnCuAO
).

Ed


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Re: [Talk-GB] building shapes from OS Street View, with code

[Tim François]

...any reason why no underscores with Potlatch?

--- On Fri, 28/5/10, Jerry Clough - OSM  wrote:

From: Jerry Clough - OSM 
Subject: Re: [Talk-GB] building shapes from OS Street View, with code
To: talk-gb@openstreetmap.org
Date: Friday, 28 May, 2010, 11:15

Potlatch's "b" option will place "source=OS OpenData StreetView" (note no 
underscores) if you have OS SV in the background. I use this as I prefer 1 
keystroke to 20 or so.

From: TimSC 
To: talk-gb@openstreetmap.org
Sent: Fri, 28 May, 2010 10:57:25
Subject: [Talk-GB] building shapes from OS Street View, with code

Ah yes, the recommended tag is
 good. I didn't notice one had been chosen 
(but it is a bit long for my taste). So use 
"source=OS_OpenData_StreetView" for verified buildings. And I will 
probably change to "source=Auto_OS_OpenData_StreetView" for automatic 
tracing in the code.

TimSC


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Re: [Talk-GB] building shapes from OS Street View, with code

[Jerry Clough - OSM]

Potlatch's "b" option will place "source=OS OpenData StreetView" (note no 
underscores) if you have OS SV in the background. I use this as I prefer 1 
keystroke to 20 or so.





From: TimSC 
To: talk-gb@openstreetmap.org
Sent: Fri, 28 May, 2010 10:57:25
Subject: [Talk-GB] building shapes from OS Street View, with code

Ah yes, the recommended tag is good. I didn't notice one had been chosen 
(but it is a bit long for my taste). So use 
"source=OS_OpenData_StreetView" for verified buildings. And I will 
probably change to "source=Auto_OS_OpenData_StreetView" for automatic 
tracing in the code.

TimSC


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[Talk-GB] building shapes from OS Street View, with code

[TimSC]

Ah yes, the recommended tag is good. I didn't notice one had been chosen 
(but it is a bit long for my taste). So use 
"source=OS_OpenData_StreetView" for verified buildings. And I will 
probably change to "source=Auto_OS_OpenData_StreetView" for automatic 
tracing in the code.

TimSC


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Re: [Talk-GB] building shapes from OS Street View, with code

[Tim François]

For a final source tag (i.e. the verified buildings) shouldn't we be using 
source=OS_OpenData_StreetView as noted in the wiki: 
http://wiki.openstreetmap.org/wiki/Ordnance_Survey_Opendata#When_tracing_over_OS_StreetView

--- On Fri, 28/5/10, Roy Jamison  wrote:

From: Roy Jamison 
Subject: Re: [Talk-GB] building shapes from OS Street View, with code
To: "TimSC" 
Cc: talk-gb@openstreetmap.org
Date: Friday, 28 May, 2010, 10:29

Also fuzzer is a bugger to get working and I don't know how to edit the
fuzzyselect.py to get it doing what I wanted (i.e. auto-tracing from OS
StreetView), so this script should definitely help!

On Fri, 2010-05-28 at 10:11 +0100, TimSC wrote:
> Hi mappers,
> 
> Thanks for the comments on automatic tracing. I have finished an 
> implementation and it is ready for testing. It runs really slowly (30 
> minutes a tile). Be careful if you try it and don't remove any existing 
> OSM information (and try not to annoy other mappers). The OS open data 
> license is also a concern, so keep the source tags where appropriate. 
> Please limit yourself to areas you are prepared to manually check and 
> fix. (The LWG are aware of this issue, but don't anticipate problems.) 
> The python code is here (with a readme file): 
> http://timsc.dev.openstreetmap.org/dev/mapseg0.1.tar.gz
> 
> Let me know if there are any major bugs or possible improvements. I am 
> not sure I can put in much time in the short term but I will fix any 
> major problems. I will do a wiki page eventually for further updates.
> 
> http://wiki.openstreetmap.org/wiki/Mapseg
> 
> As Ed Avis suggested, I flag suspected errors during the conversion. I 
> don't use the surrounding pixel colours but there are plenty of other 
> heuristics that indicate problems. I assume all buildings have at least 
> 4 sides which are orthogonal. Any non orthogonal buildings will be 
> flagged for checking.
> 
> I automatically add a source tag "auto_os_street_view". This should be 
> changed to a different source tag when it has been verified. I suggest 
> "source=os_street_view" for verified buildings.
> 
> The fuzzer plugin for JOSM is nicely integrated but it operates on the 
> rectified tiles which have lower quality images. My approach uses the 
> original opendata tiles.
> 
> TimSC
> 
> 
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Re: [Talk-GB] building shapes from OS Street View, with code

[Roy Jamison]

Also fuzzer is a bugger to get working and I don't know how to edit the
fuzzyselect.py to get it doing what I wanted (i.e. auto-tracing from OS
StreetView), so this script should definitely help!

On Fri, 2010-05-28 at 10:11 +0100, TimSC wrote:
> Hi mappers,
> 
> Thanks for the comments on automatic tracing. I have finished an 
> implementation and it is ready for testing. It runs really slowly (30 
> minutes a tile). Be careful if you try it and don't remove any existing 
> OSM information (and try not to annoy other mappers). The OS open data 
> license is also a concern, so keep the source tags where appropriate. 
> Please limit yourself to areas you are prepared to manually check and 
> fix. (The LWG are aware of this issue, but don't anticipate problems.) 
> The python code is here (with a readme file): 
> http://timsc.dev.openstreetmap.org/dev/mapseg0.1.tar.gz
> 
> Let me know if there are any major bugs or possible improvements. I am 
> not sure I can put in much time in the short term but I will fix any 
> major problems. I will do a wiki page eventually for further updates.
> 
> http://wiki.openstreetmap.org/wiki/Mapseg
> 
> As Ed Avis suggested, I flag suspected errors during the conversion. I 
> don't use the surrounding pixel colours but there are plenty of other 
> heuristics that indicate problems. I assume all buildings have at least 
> 4 sides which are orthogonal. Any non orthogonal buildings will be 
> flagged for checking.
> 
> I automatically add a source tag "auto_os_street_view". This should be 
> changed to a different source tag when it has been verified. I suggest 
> "source=os_street_view" for verified buildings.
> 
> The fuzzer plugin for JOSM is nicely integrated but it operates on the 
> rectified tiles which have lower quality images. My approach uses the 
> original opendata tiles.
> 
> TimSC
> 
> 
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[Talk-GB] building shapes from OS Street View, with code

[TimSC]

Hi mappers,

Thanks for the comments on automatic tracing. I have finished an 
implementation and it is ready for testing. It runs really slowly (30 
minutes a tile). Be careful if you try it and don't remove any existing 
OSM information (and try not to annoy other mappers). The OS open data 
license is also a concern, so keep the source tags where appropriate. 
Please limit yourself to areas you are prepared to manually check and 
fix. (The LWG are aware of this issue, but don't anticipate problems.) 
The python code is here (with a readme file): 
http://timsc.dev.openstreetmap.org/dev/mapseg0.1.tar.gz

Let me know if there are any major bugs or possible improvements. I am 
not sure I can put in much time in the short term but I will fix any 
major problems. I will do a wiki page eventually for further updates.

http://wiki.openstreetmap.org/wiki/Mapseg

As Ed Avis suggested, I flag suspected errors during the conversion. I 
don't use the surrounding pixel colours but there are plenty of other 
heuristics that indicate problems. I assume all buildings have at least 
4 sides which are orthogonal. Any non orthogonal buildings will be 
flagged for checking.

I automatically add a source tag "auto_os_street_view". This should be 
changed to a different source tag when it has been verified. I suggest 
"source=os_street_view" for verified buildings.

The fuzzer plugin for JOSM is nicely integrated but it operates on the 
rectified tiles which have lower quality images. My approach uses the 
original opendata tiles.

TimSC


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Re: [Talk-GB] building shapes from OS Street View

[Andrew]

Tom Chance  writes:

> 
> 
> On 24 May 2010 15:24, Gregory  googlemail.com> wrote:
> 
> 
> Harry has done some good blog posts about London's gaps in buildings. But this
is an area with strong mapping activity. We can leave it to locals to trace
buildings in the gaps with some memory or to hold off if they know people are
surveying it this week. In cities & towns with no buildings at all, it's better
to leave these blank and when the mappers come they can work on it.
> 
> 
> 
> 
> I think that's a bit naieve.There are still lots and lots of "noname" roads in
London, particularly in the poorer parts of outer London. Road names are really
very easy to survey and add in.After all of TimSC's work there are large parts
of London without landuse areas.Whilst Harry's mapping parties have done wonders
for POIs in Central London, the rest of the city has very patchy coverage.Even
cycle routes are incomplete and cycle parking coverage is very limited.Mapping
buildings based on surveys for accuracy is laborious by comparison, and even
after a year or more of experimentation by a few brave souls a tiny percentage
of London has seen any activity.I'm inclined to support a mass import of
automatically traced buildings with a noname layer equivalent, or a modification
to noname, to aid verification and improvement by people such as myself who are
interested in doing buildings properly.Best,Tom
> 
> 
> -- http://tom.acrewoods.net   http://twitter.com/tom_chance
> 
> 
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I appreciate what TimSC has done and would like to see use made of it if someone
can give a legal opinion that the licence is rock solid, but I do not see us as
ready for a nationwide import yet; while there is no particular problem why
buildings should not run ahead of addresses, other places where the community
has to digest the results may come to light. Perhaps the answer is to convert
the building outlines to .osm files at this stage. I would be interested in
using this where I live.

It is also worth making notes of where we do not want to import buildings from
StreetView because it is out of date or there are better sources.

--
Andrew



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Re: [Talk-GB] building shapes from OS Street View

[ael]

On Tue, May 25, 2010 at 06:24:25PM +0100, Roy Jamison wrote:
> I have tried using the JOSM plugin to trace buildings but can't get it
> to work, it keeps coming up with a problem with the child process. Is

Same here: see http://josm.openstreetmap.de/ticket/5068

ael

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[Talk-GB] building shapes from OS Street View

[Roy Jamison]

I have tried using the JOSM plugin to trace buildings but can't get it
to work, it keeps coming up with a problem with the child process. Is
there any other easy way(s) to do this - even if it's on a few
buildings? As the self-appointed 'mapping supervisor' for the Isle of
Sheppey, I'd rather have it looking nice and 'complete' and slightly
incorrect than to have nothing at all.

Roy Jamison (Teej)


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Re: [Talk-GB] building shapes from OS Street View

[Robert Whittaker (OSM)]

On 24 May 2010 16:42, Richard Fairhurst  wrote:
> Robert Whittaker (OSM) wrote:
>> My reading of 4.3 is that you would have to tell people that the
>> image was derived from OSM and that the OSM database is
>> available under ODbL.
>
> To comply with ODbL for data obtained from OSM, you have to at least provide
> attribution to OSM.
>
> That does not preclude that the data may have other attribution
> requirements, and it does not prevent you from fulfilling them.

Although it doesn't prevent any voluntary fulfilment, the ODbL terms
give you explicit rights to use the database in any way you want
without violating any copyright/contract/database rights in the
database, as long as you follow the various requirements. There's no
requirement to provide further attribution on produced works, so for
produced works from an ODbL database you would not be violating any
database rights were you to omit any other attribution requirements on
produced works.

The only other way to force users to use attribution would be via
copyright on individual data items. But the proposal is to license the
individual items in OSM under DbCL, which means there would be no
additional restrictions there.

Thus ODbL+DbCL grants users the right not to have to include
additional attribution statements on produced works, provided they
follow the rest of the requirements of ODbL. (This usually includes
releasing the database that the work was produced from under ODbL, and
the database may require additional copyright notices attached to it,
but not the produced work. This link back to the database may be
enough to satisfy some people's attribution requirements, but it won't
necessarily cover all such requirements.)

With no way to force users to add specific attribution text to
produced works, if a database contains data that requires such
attribution, I would conclude that the resulting database cannot
legally be released under ODbL+DbCL. Were someone to do so, they'd be
giving people a license to do stuff that they don't have the right to
offer. (Kind of like releasing an image obtained under CC-By as CC0.)

-- 
Robert Whittaker

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Re: [Talk-GB] building shapes from OS Street View

[Richard Fairhurst]

Robert Whittaker (OSM) wrote:
> My reading of 4.3 is that you would have to tell people that the 
> image was derived from OSM and that the OSM database is 
> available under ODbL.

To comply with ODbL for data obtained from OSM, you have to at least provide
attribution to OSM.

That does not preclude that the data may have other attribution
requirements, and it does not prevent you from fulfilling them.

cheers
Richard
-- 
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Re: [Talk-GB] building shapes from OS Street View

[Robert Whittaker (OSM)]

On 24 May 2010 14:56, Richard Fairhurst  wrote:
> Robert Whittaker (OSM) wrote:
>> My understanding is that the current terms from OS are
>> incompatible with ODbL (in particular the part that allows
>> produced works to be released to the public domain).
>
> This is a canard and I wish it would stop coming up. ODbL does _not_ say
> that Produced Works can be released entirely without restriction (US "public
> domain").
>
> 4.3 is very clear that "if you Publicly Use a Produced Work, You must
> include a notice associated with the Produced Work reasonably calculated to
> make any Person that uses, views, accesses, interacts with, or is otherwise
> exposed to the Produced Work aware that Content was obtained from the
> Database, Derivative Database, or the Database as part of a Collective
> Database, and that it is available under this License".
>
> OS OpenData is released under an attribution-only licence (compatible with
> CC-BY) and the terms of attribution are, in my entirely unqualified view,
> satisfied by ODbL 4.3.

My reading of 4.3 is that you would have to tell people that the image
was derived from OSM and that the OSM database is available under
ODbL. As far as I can see, 4.3 contains nothing to specify what
license you are or aren't allowed to release the produced work under,
nor anything to require you to maintain a specific attribution
statement from the third-party data supplier such as OS.

If I'm allowed under ODbL to release an image with only the statement
"Contains information from DATABASE NAME, which is made available here
under the Open Database License (ODbL)." as suggested by the ODbL
text, then this is surely in contravention of the attribution
requirements specified by OS as (a) I haven't included their specific
attribution/copyright text, and (b) I haven't had to place any
restrictions on other users of my image that would require them to
provide any such attribution either.

Both of the following links seem to suggest you should be able to
release "produced work" images in this way:

http://wiki.openstreetmap.org/wiki/Open_Data_License/Use_Cases#Using_OSM_data_in_a_raster_map_for_a_book.2C_newsletter.2C_website.2C_blog_or_similar_work

http://wiki.openstreetmap.org/wiki/Open_Data_License_FAQ#How_does_this_affect_Wikipedia_and_other_projects_that_want_to_use_our_maps.3F

Anyway, even if this turns out to be a non-issue, there is still the
problem of getting OS to agree to the new contributor terms if OSMF
decides they need all OSM data under them. I really can't see OS being
happy with either OSMF's right to re-license or the terms of DbCL.

-- 
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Re: [Talk-GB] building shapes from OS Street View

[Tom Chance]

On 24 May 2010 15:24, Gregory  wrote:

> Harry has done some good blog posts about London's gaps in buildings. But
> this is an area with strong mapping activity. We can leave it to locals to
> trace buildings in the gaps with some memory or to hold off if they know
> people are surveying it this week. In cities & towns with no buildings at
> all, it's better to leave these blank and when the mappers come they can
> work on it.
>
>
I think that's a bit naieve.

There are still lots and lots of "noname" roads in London, particularly in
the poorer parts of outer London. Road names are really very easy to survey
and add in.

After all of TimSC's work there are large parts of London without landuse
areas.

Whilst Harry's mapping parties have done wonders for POIs in Central London,
the rest of the city has very patchy coverage.

Even cycle routes are incomplete and cycle parking coverage is very limited.

Mapping buildings based on surveys for accuracy is laborious by comparison,
and even after a year or more of experimentation by a few brave souls a tiny
percentage of London has seen any activity.

I'm inclined to support a mass import of automatically traced buildings with
a noname layer equivalent, or a modification to noname, to aid verification
and improvement by people such as myself who are interested in doing
buildings properly.

Best,
Tom

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Re: [Talk-GB] building shapes from OS Street View

[Ian Spencer]

Ed Avis wrote on 24/05/2010 15:05:
> It appears the choice for buildings is a fight between OS maps, which are 
> likely
> derived from high-resolution aerial photos but have been simplified, and the
> somewhat lower-resolution photo images available to OSM.  It is not really
> possible to survey building shapes on the ground since GPS isn't precise 
> enough,
> even if we had enough mappers to walk round the outside of every building.
>
> In London the Yahoo photos are adequate for tracing streets, but trying to get
> buildings from them is a bit ropey.  Hence my feeling that the OS data is of
> higher quality, even though it's clearly a simplification of the real shape.
> But in other, less crowded parts of the country a semi-automated trace from
> aerial photos (using the Fuzzer JOSM plugin you mention) might be a better 
> way.
>
> (Indeed, it might be fun to trace the whole country using both methods and 
> then
> highlight differences between the two.)
>
> I still believe we could do *something* to get reasonably good building shapes
> into the map without waiting for the man-years needed to hand-survey them all.
> Even in an area which is not any mapper's particular 'territory'.  The 
> workflow
> might be to view the aerial photograph with the OS-traced building shapes on 
> top,
> and then either press a button to import the whole area or select individual
> shapes.
>
>
Taking the lead from StreetView in my area, the shapes around are better 
than nothing and are good for making sense of the map. With appropriate 
tagging, which is trivial with a bulk import, then it becomes easy 
enough to have a to-do list. Areas of little interest to people will be 
populated adequately, and areas where people are interested, they should 
know from the source (perhaps even an automated note) that they have 
carte-blanche to improve it.

A Wiki-Map does have the danger of trying to be all things to all men, 
and it is interesting to see from a single source that the cyclists can 
produce an appropriate map different from the general. If people are 
really uncomfortable with the impurity of the data (in the sense of 
reliability not licence), then the right approach to me is to have a 
specific tag that is internationally agreed to be unverified/suspect and 
then map producers can filter or represent that data as they deem 
appropriate, without the map editors needing to prejudge an appropriate 
solution. It would also be useful to then make PotLatch et al sensitive 
to the tag. (BTW, it may be that this already exists, but there does not 
seem to be anything from my cursory look).

That is not just for this extracted data, there are times I have looked 
at an area I know well and can't believe it does not mark a path that I 
know well. I would rather put the path in temporarily with a warning 
that it needs to be verified for exact alignment, and gets on to a to do 
list, than not mark it at all. I'll walk it eventually, but on a map it 
might get noted and verified by someone else.

Spenny

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Re: [Talk-GB] building shapes from OS Street View

[Gregory]

On 24 May 2010 14:43, Richard Fairhurst  wrote:

>
> I don't know what the quality of StreetView is like in your area, but I
> would weep if someone were to blindly trace from StreetView in Charlbury
> without ever having visited it. The building outlines just aren't that
> great. Let's not lose sight of OSM's strengths in an enthusiasm to slurp as
> much free data as possible.


If someone traces Hampton or Durham buildings with no intention of
on-the-ground surveying then I too will -well I won't cry, but I'll say some
angry words in the irc #osm channel. I'm getting annoyed enough at having to
fix over-keen landuse. It's not about the accuracy of the imagery(aerial or
OS) but about knowing the area, and finding out when a building might
need splitting with a gap or when they no longer exist due to recent
redevelopment.

Harry has done some good blog posts about London's gaps in buildings. But
this is an area with strong mapping activity. We can leave it to locals to
trace buildings in the gaps with some memory or to hold off if they know
people are surveying it this week. (Plug if your in the area, come to
http://wiki.openstreetmap.org/wiki/London/Summer_2010_mapping_parties ). In
cities & towns with no buildings at all, it's better to leave these blank
and when the mappers come they can work on it.

I know I don't like armchair mappers (or rather I don't want to be one).
There is a difference between tracing roads without names (helpful to route
between mapped cities or to the next unmapped place) and mapping every
unknown building (most information can be added to a node if the building
isn't there, even without a GPS people can survey and add this information
themselves).

I have been thinking about these people who like sitting at a hot computer.
Now I am doing house numbers/names it could be helpful to have someone trace
building outlines for me so that I have more free time to go outside and get
the information to add to and correct the details. I've briefly asked in irc
(and had no takers), but when I have I included details of where to not go
beyond, because I know some areas could easily be confused as to what they
are without local knowledge. This is the case for OS StreetView, and the
Surrey Aerial Imagery (still confused on the latter license). It might be
nice to have somewhere to request help from 'armchair mappers' this could
also be good for the crisis requests.

-- 
Gregory
o...@livingwithdragons.com
http://www.livingwithdragons.com
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Re: [Talk-GB] building shapes from OS Street View

[Tom Chance]

On 24 May 2010 14:43, Richard Fairhurst  wrote:

>
> Tom Chance wrote:
> > Getting buildings right is extremely time-intensive work
>
> It shouldn't be. The tools should help.
>
>
I should have elaborated. I've found that the OS building shapes are very
simplified, and often quite wrong. Not to mention lots of text over the top
of shapes where there are place names, "School", etc.

My approach has been to use the OS StreetView Data, Yahoo! imagery and
personal surveys together, manually drawing then copying+pasting buildings
where their shapes aren't just simple rectangles, or creating the terrace
then extruding the correct shape for each home.

There's a big difference in effort between a single untagged rectangle
representing a terrace of houses (traced from StreetView, say), and that
terrace being split into individual buildings with their correct shape and
house number.

The former could be automated for the country to provide a basic navigation
aid. The latter needs a fair bit of mapping time for address searching and
other uses where precision is necessary.

Best,
Tom

-- 
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Re: [Talk-GB] building shapes from OS Street View

[Ed Avis]

It appears the choice for buildings is a fight between OS maps, which are likely
derived from high-resolution aerial photos but have been simplified, and the
somewhat lower-resolution photo images available to OSM.  It is not really
possible to survey building shapes on the ground since GPS isn't precise enough,
even if we had enough mappers to walk round the outside of every building.

In London the Yahoo photos are adequate for tracing streets, but trying to get
buildings from them is a bit ropey.  Hence my feeling that the OS data is of
higher quality, even though it's clearly a simplification of the real shape.
But in other, less crowded parts of the country a semi-automated trace from
aerial photos (using the Fuzzer JOSM plugin you mention) might be a better way.

(Indeed, it might be fun to trace the whole country using both methods and then
highlight differences between the two.)

I still believe we could do *something* to get reasonably good building shapes
into the map without waiting for the man-years needed to hand-survey them all.
Even in an area which is not any mapper's particular 'territory'.  The workflow
might be to view the aerial photograph with the OS-traced building shapes on 
top,
and then either press a button to import the whole area or select individual
shapes.

-- 
Ed Avis 


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Re: [Talk-GB] building shapes from OS Street View

[Richard Fairhurst]

Robert Whittaker (OSM) wrote:
> My understanding is that the current terms from OS are 
> incompatible with ODbL (in particular the part that allows 
> produced works to be released to the public domain).

This is a canard and I wish it would stop coming up. ODbL does _not_ say
that Produced Works can be released entirely without restriction (US "public
domain").

4.3 is very clear that "if you Publicly Use a Produced Work, You must
include a notice associated with the Produced Work reasonably calculated to
make any Person that uses, views, accesses, interacts with, or is otherwise
exposed to the Produced Work aware that Content was obtained from the
Database, Derivative Database, or the Database as part of a Collective
Database, and that it is available under this License".

OS OpenData is released under an attribution-only licence (compatible with
CC-BY) and the terms of attribution are, in my entirely unqualified view,
satisfied by ODbL 4.3.

cheers
Richard
-- 
View this message in context: 
http://gis.638310.n2.nabble.com/building-shapes-from-OS-Street-View-tp5091506p5093953.html
Sent from the Great Britain mailing list archive at Nabble.com.

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Re: [Talk-GB] building shapes from OS Street View

[Richard Fairhurst]

Tom Chance wrote:
> Getting buildings right is extremely time-intensive work 

It shouldn't be. The tools should help.

JOSM has a plugin called Fuzzer which will trace from imagery (
http://wiki.openstreetmap.org/wiki/JOSM/Plugins/Fuzzer), and a built-in tool
to square up edges. This should be ideal for getting building outlines in
with minimal effort, and I would recommend people use it.

 "Where is the real RichardF, and what have you done with him?"


Oh, ok then. Potlatch 2 has a similar squaring-up tool already (thanks
Matt), and will in time have Fuzzer-like capabilities. (There's a wonderful
ActionScript 3 library for that. There's a wonderful AS3 library for most
things, in fact.)

I don't know what the quality of StreetView is like in your area, but I
would weep if someone were to blindly trace from StreetView in Charlbury
without ever having visited it. The building outlines just aren't that
great. Let's not lose sight of OSM's strengths in an enthusiasm to slurp as
much free data as possible.

cheers
Richard
-- 
View this message in context: 
http://gis.638310.n2.nabble.com/building-shapes-from-OS-Street-View-tp5091506p5093902.html
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Re: [Talk-GB] building shapes from OS Street View

[Tom Chance]

On 24 May 2010 13:02, Ed Avis  wrote:

>
> Fundamentally, though, our goal is surely to get the best possible free
> map.
> Even in a town where no OSM contributor lives, the OS data makes a valuable
> contribution.  The building shapes are simplified, to be sure, but
> generally
> superior in quality to those that have been traced from the fairly low-res
> Yahoo
> imagery.  So by all means take care of your local area first, but we
> shouldn't
> lose sight of the broad goal of nationwide coverage.  If we need to get
> more OSM
> contributors in unmapped parts of the country, one of the best ways to do
> that is
> to give them the best head start possible by 'armchair mapping'.
>

I have to agree - let's automatically trace buildings for the whole country
with a verification tag attached to every building, and add a rule to the
nonames layer or create a similar layer.

Here in London there are huge swathes that will simply never get done by any
other method because we haven't got enough active mappers. Getting buildings
right is extremely time-intensive work compared to basic roads and green
spaces, which is where much of London remains after the tracing and mapping
parties.

Building shapes are quite different to importing post offices, road layouts
and other specific things that definitely need verification on the ground
before being added to the database.

Regards,
Tom

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Re: [Talk-GB] building shapes from OS Street View

[Ed Avis]

Gregory  writes:

[trace buildings from OS]

>>Once this gets going we can produce a 'buildings noname' map for people to go
>>out and verify the position and street address of buildings.
> 
>I didn't think anyone was suggesting this be done on any kind of expansive
>area. It shouldn't be done beyond a mappers 'territory' or 'reach'.

When I first started mapping in OSM the London streets had been traced from 
Yahoo
aerial photos but there were large unnamed areas, including the area where I
lived.  Immediately I could go out and start finding names without needing to
know too much about tagging, how to draw shapes, or owning a GPS device.  If the
existing mappers had limited themselves to their own local areas, then faced 
with
a blank canvas it would be more difficult for beginners to start mapping.

Fundamentally, though, our goal is surely to get the best possible free map.
Even in a town where no OSM contributor lives, the OS data makes a valuable
contribution.  The building shapes are simplified, to be sure, but generally
superior in quality to those that have been traced from the fairly low-res Yahoo
imagery.  So by all means take care of your local area first, but we shouldn't
lose sight of the broad goal of nationwide coverage.  If we need to get more OSM
contributors in unmapped parts of the country, one of the best ways to do that 
is
to give them the best head start possible by 'armchair mapping'.

-- 
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Re: [Talk-GB] building shapes from OS Street View

[Gregory]

On 24 May 2010 11:16, Ed Avis  wrote:

> Once this gets going we can produce a 'buildings noname' map for people to
> go
> out and verify the position and street address of buildings.
>
>
I didn't think anyone was suggesting this be done on any kind of expansive
area. It shouldn't be done beyond a mappers 'territory' or 'reach'.

For example I am starting a process where I trace a few blocks of buildings,
go out and map them (might be 2-4 trips worth) and then when I've
edited/uploaded that area I begin tracing again. This helps people see that
mapping is happening in the area, there is probably no point getting house
numbers for the buildings because I may be out surveying them already,
instead trace some more buildings. Example: http://osm.org/go/euuOoSiY

With such a tool as is being described I could trace more buildings, but I
would still restrict this to what I expect to survey in a month or two.
(longer than that and I might have moved home and abandon mapping the area,
or mapping tactic/direction might change)

-- 
Gregory
o...@livingwithdragons.com
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Re: [Talk-GB] building shapes from OS Street View

[Ed Avis]

TimSC  writes:

>I have done a small test of automatically tracing buildings from OS 
>Street View.

>http://osm.org/go/eurUp7x0Q-
> 
>The biggest problem I can see is where roads or text labels obsure the 
>buildings.

Yes, in those cases you just have to guess where the building might go,
usually by assuming it is rectangular.  The OS Street View map simplifies
many buildings to rectangles anyway.  Can the code notice that the outside
of the building is not the usual light-coloured background, and so either
guess a plausible outline for the obscured bit, or flag the building for
extra manual checking?

>I guess the fundamental question is, is this 
>quicker than doing the whole thing manually?

Undoubtedly, and also on the whole less error-prone.

Once this gets going we can produce a 'buildings noname' map for people to go
out and verify the position and street address of buildings.

-- 
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Re: [Talk-GB] building shapes from OS Street View

[Robert Whittaker (OSM)]

On 23 May 2010 20:00, TimSC  wrote:
> I have done a small test of automatically tracing buildings from OS
> Street View. I have limited this to Wood Street Village, near Guildford.
> I have not done any manual improvements but these should be done to
> improve the quality. I am not doing that yet so people can take a look
> at the result. It seems acceptable to me. I have implemented the code in
> python and uploaded it using JOSM. There was a glitch with duplicate
> nodes which JOSM validator fixed, I need to root out the cause in my code.
>
> http://osm.org/go/eurUp7x0Q-

Nice work. :-)

However, not wanting to pour cold water on everyone's efforts with OS
Open Data, but before we all invest too much time in using OS
OpenData...

My understanding is that the current terms from OS are incompatible
with ODbL (in particular the part that allows produced works to be
released to the public domain). OS might well be persuaded to dual
license under ODbL-compatible terms, but I'm not sure they'll be
prepared to agree to the "give OSMF the right to re-license under
as-yet unspecified terms" part of the proposed new contributor terms.

If OSM does indeed change to ODbL and/or OSMF want to ensure they have
the right to re-license content we may well have to remove all OS
OpenData derived data from OSM. This would be a great shame, and I'd
hope that we will be able to work something out. But would be an even
greater shame if people had invested lots of time in importing /
tracing stuff that later had to be removed.

We should probably get someone from OSMF LWG to contact OS to see what
options they might consider. In the mean time, if we do use OS
OpenData in OSM, we should be very careful to add proper source tags
so it can be identified and removed later if necessary.

Robert.

-- 
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Re: [Talk-GB] building shapes from OS Street View

[Gregory]

On 23 May 2010 20:00, TimSC  wrote:

> I guess the fundamental question is, is this
> quicker than doing the whole thing manually?


For buildings that are semi-detached or terraces, the terracer plugin seems
to pay attention to the order the nodes were created/numbered, and thus on
which side to split the building up (I suppose if it's fairly
square-shaped). I don't see that a colour-reading auto-tracer could decide
on which side to start drawing the building.
For this reason I think it is quicker to use the building plugin to trace
and then be ready to split up for numbering.

But don't let me discourage your work and anyone who would find it useful.
It is probably that this case is based on my current mapping of lots of
square-ish buildings that are often semi-detached.

Actually, we haven't thought if this would be helpful in any areas if
altered for use on ponds/lakes (not really rivers broken by many bridges)
and/or green woods/parks.

-- 
Gregory
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Re: [Talk-GB] building shapes from OS Street View

[Andrew]

TimSC  writes:

> 
> 
> Hi all,
> 
> I have done a small test of automatically tracing buildings from OS 
> Street View. I have limited this to Wood Street Village, near Guildford. 

That is a nice piece of work. It is not as good as you could get from the Surrey
aerial photographs but no worse and more consistent than tracing Yahoo pictures.
One thing to watch is that it only imports the orange inside of public 
buildings.

--
Andrew



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[Talk-GB] building shapes from OS Street View

[TimSC]

Hi all,

I have done a small test of automatically tracing buildings from OS 
Street View. I have limited this to Wood Street Village, near Guildford. 
I have not done any manual improvements but these should be done to 
improve the quality. I am not doing that yet so people can take a look 
at the result. It seems acceptable to me. I have implemented the code in 
python and uploaded it using JOSM. There was a glitch with duplicate 
nodes which JOSM validator fixed, I need to root out the cause in my code.

http://osm.org/go/eurUp7x0Q-

The biggest problem I can see is where roads or text labels obsure the 
buildings. This probably can be handled by manually checking the 
building outlines. So we might want to automatically get the outlines 
and do manual quality control. It might be worth manually using the JOSM 
orthogalise where required. I guess the fundamental question is, is this 
quicker than doing the whole thing manually?

http://www.openstreetmap.org/browse/way/60094590

For far this is only a subsection of a tile. More work is required if we 
want to stream line things.

Any thoughts? *ducks*

TimSC


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Re: [Talk-GB] building shapes from OS Street View

[Robert Scott]

On Saturday 10 April 2010, TimSC wrote:
> Converting edge fragments to polygons is the slow step at the moment - 
> about 15 minutes a tile. I am using the approach describe in the link 
> below. Fortunately, I know a bit of Boost.Python and C++ if we need the 
> speed. I suspect a better algorithm in python could improve the speed 
> issue rather than resorting to C++.

If needs be, and other algorithms fall short, the advantages c++ has are things 
like ability to optimize for cache behaviour, ability to choose algorithms for 
your data structures (such as lists) which I imagine are getting hammered by 
your approach. A last resort though.

> 
> http://losingfight.com/blog/2007/08/28/how-to-implement-a-magic-wand-tool/
> 
> I am also seeing the limitations of my approach. Problems arise from the 
> lack of image resolution and the anti-aliasing of the colours in the 
> image. Since I am using a binary classification by colour for selecting 
> pixels, it tends to result in rounded corners (due to the colour 
> blending into the backgound). The polygon simplification then has to 
> descriminate between a rounded corner due to anti-aliasing and corner 
> which is real. Given the resolution, a straight edge might only be 2 or 
> 3 pixels long, and a rounded corner has a radius of about... 2 or 3 
> pixels. But then, these building shapes are also a total nightmare to 
> manually survey. Example attached (you will probably need to zoom in):

Indeed. The approach I was going to take was taking the buildings as 
anti-aliased grayscale ( which I guess I would have to be generated by tuning a 
few heuristics about which indexed colours to pick ) and use a corner finding 
algorithm on them. I was hoping to be able to get sub-pixel accuracy with this 
approach (corner detectors are perfectly capable of it with grayscale data), 
but I still have a few papers to read.

I was thinking momentarily of a hybrid approach, using detected corners to more 
precisely position nodes.

As far as the orthogonalizer idea goes, I think a simple refinement would need 
to be made - orthogonalization threshold would need to be inversely 
proportional to segment lengths. Lengths that are short relative to pixel size 
will have more quantization errors than long segments.

> I have some ideas for a better algorithm (based on active contour 
> models), but that is pretty complex. I will give that some thought. 
> Basically, we need to segment the shape but not by simply binary 
> selecting pixels inside or outside the shape (and it can try to be 
> orthogonal, if possible). The code I have does provide a good 
> initialisation of the model, so it is hardly wasted effort. If anyone 
> has any better ideas, you can have a copy of my python code to try things.

You've done a lot better than me - I'm still at the 'reading papers' stage ;)


robert.

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[Talk-GB] building shapes from OS Street View

[TimSC]

Hi again, thanks for the comments.
> How well would this scale up to the whole country? (!! Not automatically 
> importing the results of course !!) I'm thinking about tile/batch sizes, tile 
> boundary issues, 
I was thinking about using a sliding window approach, by loading in an 
extra margin from surrounding tiles, selection pixels by colour, create 
edge fragments as before. But in this case, the step that creating 
polygons should only use the central region of the image for the 
starting point of the polygon. This should avoid any buildings getting 
cut in half at the tile edge.

> any necessity for porting parts to c++ for speed etc.
>   
Converting edge fragments to polygons is the slow step at the moment - 
about 15 minutes a tile. I am using the approach describe in the link 
below. Fortunately, I know a bit of Boost.Python and C++ if we need the 
speed. I suspect a better algorithm in python could improve the speed 
issue rather than resorting to C++.

http://losingfight.com/blog/2007/08/28/how-to-implement-a-magic-wand-tool/

I am also seeing the limitations of my approach. Problems arise from the 
lack of image resolution and the anti-aliasing of the colours in the 
image. Since I am using a binary classification by colour for selecting 
pixels, it tends to result in rounded corners (due to the colour 
blending into the backgound). The polygon simplification then has to 
descriminate between a rounded corner due to anti-aliasing and corner 
which is real. Given the resolution, a straight edge might only be 2 or 
3 pixels long, and a rounded corner has a radius of about... 2 or 3 
pixels. But then, these building shapes are also a total nightmare to 
manually survey. Example attached (you will probably need to zoom in):

http://timsc.dev.openstreetmap.org/dev/hard-building-shapes.png

I have some ideas for a better algorithm (based on active contour 
models), but that is pretty complex. I will give that some thought. 
Basically, we need to segment the shape but not by simply binary 
selecting pixels inside or outside the shape (and it can try to be 
orthogonal, if possible). The code I have does provide a good 
initialisation of the model, so it is hardly wasted effort. If anyone 
has any better ideas, you can have a copy of my python code to try things.

Regards,

TimSC


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Re: [Talk-GB] building shapes from OS Street View

[Ed Loach]

Glenn wrote:

> JOSM has an "Orthogonalise shape" option which is very useful
> for buildings.

And a terracer plugin which I find useful for converting traced
buildings to semi-detached* (or however many) properties.

Ed

* Slight issue when the width of the two semi-detached houses
together is less than their depth as it then splits the rectangle on
the wrong axis, but this seems fairly rare around here (and I now
know how to rotate objects in JOSM as a result).



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Re: [Talk-GB] building shapes from OS Street View

[Dave Stubbs]

> It's worth noting that the Yahoo aerial photography is also out of date; in 
> some
> cases [1] people have traced streets from the photo which bear no relation to
> what's on the ground.  Yet nobody suggests we should stop tracing from it.

Yes they do.
http://lists.openstreetmap.org/pipermail/talk/2007-September/017830.html

I've slightly changed my mind since then, but anyway.

Dave

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Re: [Talk-GB] building shapes from OS Street View

[Ed Avis]

Simon Ward  writes:

>Having looked at some of the StreetView data aroud my area, it is not
>very accurate at all (probably out of date).
>
>This isn’t something we can just blindly import, trace, or otherwise use
>and assume it’s of better quality.

In areas where we already have some mapping coverage we clearly need to check
that the OS map is consistent with what we have.  However, there are still large
parts of the country with little or no coverage in OSM, and in those cases we
certainly can assume that the OS data is better.

It's worth noting that the Yahoo aerial photography is also out of date; in some
cases [1] people have traced streets from the photo which bear no relation to
what's on the ground.  Yet nobody suggests we should stop tracing from it.

The places where OSM is weakest tend to be villages and rural towns; these are
also those that change slowly, so the OS map is likely to be reasonably current.

[1] 
http://www.openstreetmap.org/?lat=51.56496&lon=-0.04983&zoom=17&layers=B000FTF
I recently fixed this by a GPS survey; the warehouses and service roads have
been replaced by housing.  The OS Street View map is up-to-date in this area.

-- 
Ed Avis 


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Re: [Talk-GB] building shapes from OS Street View

[Glenn Proctor]

On Sat, Apr 10, 2010 at 9:23 AM, Steve Doerr
 wrote:

> Orthogonal snapping would be useful more generally - do any of the editors
> have this feature for manually drawn buildings etc.?

JOSM has an "Orthogonalise shape" option which is very useful for buildings.

Glenn.

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Re: [Talk-GB] building shapes from OS Street View

[Steve Doerr]

From: "Robert Scott" 

> That's great! I can stop reading about Harris operators. I totally agree 
> about orthogonal snapping.

Orthogonal snapping would be useful more generally - do any of the editors 
have this feature for manually drawn buildings etc.?

-- 
Steve 



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Re: [Talk-GB] building shapes from OS Street View

[Robert Scott]

Hey,

That's great! I can stop reading about Harris operators. I totally agree about 
orthogonal snapping.

How well would this scale up to the whole country? (!! Not automatically 
importing the results of course !!) I'm thinking about tile/batch sizes, tile 
boundary issues, any necessity for porting parts to c++ for speed etc.


robert.


On Friday 09 April 2010, TimSC wrote:
> Hi again,
> 
> I have been working on auto tracing buildings and I'm making progress. I 
> was slightly encouraged by Ed Avis's comments. I think one underlying 
> difference is peoples attitude to omissions in map data. Many people 
> think they are a good thing, particularly since they encourage the 
> community to do high quality surveying. But I think omissions are bad in 
> terms of actually using the map. I don't think we should be using the 
> main map to gauge our progress. I suspect what we need is good meta data 
> - how and when data is sourced. Anyway enough rambling...
> 
> Tracing buildings. I have been using the original images, since image 
> transformations tend to introduce degradation of quality. I use colour 
> to select building pixels, then form edge fragments, then form polygons, 
> then simplify the polygons using the Douglas-Peucker algorithm, then 
> group them so we get inner and outer edges, then tranform image 
> coordinates to GBOS then to WGS84 via OSTN02 (I ported the perl code to 
> python), then save as OSM format and load back into JOSM. Screenshot: 
> http://timsc.dev.openstreetmap.org/dev/josm-building-outlines.png
> 
> The next steps are to improve the quality of the polygon shapes, 
> possibly by checking if the edges are nearly orthogonal, and if so 
> making them completely orthogonal. Also I need to write a filter to 
> check for buildings in the area, to avoid importing duplicate buildings. 
> I need to look at the simplification, as sometimes an extra node is 
> added to a polygon (the initial node used as the start of the 
> algorithm). I am also considering detecting roads that overlap buildings 
> in the source images, since this is probably the biggest loss of 
> quality. The result I am getting is already more spatially detailed than 
> my own survey of the University of Surrey campus (although not as rich 
> in information).
> 
> In the medium term, I will import some buildings once I have the quality 
> I want. I want to minimise manual work in JOSM but I don't rule it out. 
> I will only be working in the Guildford area - it's my data to gamble 
> around there :)
> 
> TimSC
> 
> 
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Re: [Talk-GB] building shapes from OS Street View

[Seventy 7]

 Yeah, me too. I was just about to do that! 

Fantastic!

  - Original Message -
  From: "Graham Jones"
  To: TimSC
  Cc: talk-gb@openstreetmap.org
  Subject: Re: [Talk-GB] building shapes from OS Street View
  Date: Fri, 9 Apr 2010 22:32:40 +0100

  Hi Tim,That is exactly the sort of thing I had envisaged writing -
  you have nearly finished before I got started - well done!
  Graham.

  On 9 April 2010 22:25, TimSC  wrote:

Hi again,

I have been working on auto tracing buildings and I'm making
progress. I
was slightly encouraged by Ed Avis's comments. I think one
underlying
difference is peoples attitude to omissions in map data. Many
people
think they are a good thing, particularly since they encourage
the
community to do high quality surveying. But I think omissions are
bad in
terms of actually using the map. I don't think we should be using
the
main map to gauge our progress. I suspect what we need is good
meta data
- how and when data is sourced. Anyway enough rambling...

Tracing buildings. I have been using the original images, since
image
transformations tend to introduce degradation of quality. I use
colour
to select building pixels, then form edge fragments, then form
polygons,
then simplify the polygons using the Douglas-Peucker algorithm,
then
group them so we get inner and outer edges, then tranform image
coordinates to GBOS then to WGS84 via OSTN02 (I ported the perl
code to
python), then save as OSM format and load back into JOSM.
Screenshot:
http://timsc.dev.openstreetmap.org/dev/josm-building-outlines.png

The next steps are to improve the quality of the polygon shapes,
possibly by checking if the edges are nearly orthogonal, and if
so
making them completely orthogonal. Also I need to write a filter
to
check for buildings in the area, to avoid importing duplicate
buildings.
I need to look at the simplification, as sometimes an extra node
is
added to a polygon (the initial node used as the start of the
algorithm). I am also considering detecting roads that overlap
buildings
in the source images, since this is probably the biggest loss of
quality. The result I am getting is already more spatially
detailed than
my own survey of the University of Surrey campus (although not as
rich
in information).

In the medium term, I will import some buildings once I have the
quality
I want. I want to minimise manual work in JOSM but I don't rule
it out.
I will only be working in the Guildford area - it's my data to
gamble
around there :)

TimSC


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  --
  Dr. Graham Jones
  Hartlepool, UK
  email: grahamjones...@gmail.com

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Re: [Talk-GB] building shapes from OS Street View

[Graham Jones]

Hi Tim,
That is exactly the sort of thing I had envisaged writing - you have nearly
finished before I got started - well done!

Graham.

On 9 April 2010 22:25, TimSC  wrote:

> Hi again,
>
> I have been working on auto tracing buildings and I'm making progress. I
> was slightly encouraged by Ed Avis's comments. I think one underlying
> difference is peoples attitude to omissions in map data. Many people
> think they are a good thing, particularly since they encourage the
> community to do high quality surveying. But I think omissions are bad in
> terms of actually using the map. I don't think we should be using the
> main map to gauge our progress. I suspect what we need is good meta data
> - how and when data is sourced. Anyway enough rambling...
>
> Tracing buildings. I have been using the original images, since image
> transformations tend to introduce degradation of quality. I use colour
> to select building pixels, then form edge fragments, then form polygons,
> then simplify the polygons using the Douglas-Peucker algorithm, then
> group them so we get inner and outer edges, then tranform image
> coordinates to GBOS then to WGS84 via OSTN02 (I ported the perl code to
> python), then save as OSM format and load back into JOSM. Screenshot:
> http://timsc.dev.openstreetmap.org/dev/josm-building-outlines.png
>
> The next steps are to improve the quality of the polygon shapes,
> possibly by checking if the edges are nearly orthogonal, and if so
> making them completely orthogonal. Also I need to write a filter to
> check for buildings in the area, to avoid importing duplicate buildings.
> I need to look at the simplification, as sometimes an extra node is
> added to a polygon (the initial node used as the start of the
> algorithm). I am also considering detecting roads that overlap buildings
> in the source images, since this is probably the biggest loss of
> quality. The result I am getting is already more spatially detailed than
> my own survey of the University of Surrey campus (although not as rich
> in information).
>
> In the medium term, I will import some buildings once I have the quality
> I want. I want to minimise manual work in JOSM but I don't rule it out.
> I will only be working in the Guildford area - it's my data to gamble
> around there :)
>
> TimSC
>
>
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-- 
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email: grahamjones...@gmail.com
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[Talk-GB] building shapes from OS Street View

[TimSC]

Hi again,

I have been working on auto tracing buildings and I'm making progress. I 
was slightly encouraged by Ed Avis's comments. I think one underlying 
difference is peoples attitude to omissions in map data. Many people 
think they are a good thing, particularly since they encourage the 
community to do high quality surveying. But I think omissions are bad in 
terms of actually using the map. I don't think we should be using the 
main map to gauge our progress. I suspect what we need is good meta data 
- how and when data is sourced. Anyway enough rambling...

Tracing buildings. I have been using the original images, since image 
transformations tend to introduce degradation of quality. I use colour 
to select building pixels, then form edge fragments, then form polygons, 
then simplify the polygons using the Douglas-Peucker algorithm, then 
group them so we get inner and outer edges, then tranform image 
coordinates to GBOS then to WGS84 via OSTN02 (I ported the perl code to 
python), then save as OSM format and load back into JOSM. Screenshot: 
http://timsc.dev.openstreetmap.org/dev/josm-building-outlines.png

The next steps are to improve the quality of the polygon shapes, 
possibly by checking if the edges are nearly orthogonal, and if so 
making them completely orthogonal. Also I need to write a filter to 
check for buildings in the area, to avoid importing duplicate buildings. 
I need to look at the simplification, as sometimes an extra node is 
added to a polygon (the initial node used as the start of the 
algorithm). I am also considering detecting roads that overlap buildings 
in the source images, since this is probably the biggest loss of 
quality. The result I am getting is already more spatially detailed than 
my own survey of the University of Surrey campus (although not as rich 
in information).

In the medium term, I will import some buildings once I have the quality 
I want. I want to minimise manual work in JOSM but I don't rule it out. 
I will only be working in the Guildford area - it's my data to gamble 
around there :)

TimSC


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Re: [Talk-GB] building shapes from OS Street View

[Ed Avis]

Andy Robinson (blackadder-lists  writes:

>But what is the point of just doing building=yes. Does that really add to
>OSM? Surely tracing buildings (with aids or not) would be better associated
>with address data inclusion rather than just making a pretty map?

You might consider it analogous to streets: at first they were mostly traced
from aerial photos, and then mappers visited on the ground to fill in names
(and other things as a side effect).  This is certainly what I've been doing
for the past couple of years.

So yes, it would be great to trace the buildings from the OS maps (which
would be just as accurate as tracing them from low-res aerial photos) and
get them into OSM, even if the address is missing.  If the NoNames map then
highlighted buildings missing address info, that would motivate people to get
out and add the addresses.

(FWIW, I think just building shapes without any addresses are still useful,
especially on council estates and other areas that lack clearly defined 
streets.)

-- 
Ed Avis 


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Re: [Talk-GB] building shapes from OS Street View

[Ed Avis]

Dave Stubbs  writes:

>London has a lot of buildings, but only in certain areas. What I don't want to
>have to do is wake up one morning to discover someone has helpfully
>imported auto-detected rectangles over the top, meaning I have to
>spend the next three days/years cleaning up the data. If all you want
>to do is load some buildings into an area (however that's
>implemented), fix it up to avoid duplicates and conflicts with
>existing data such as roads, and upload that, then fine.

I think it's safe to say that nobody is proposing to indiscriminately dump
buildings or anything else over the top of existing mapping.  That could only
be appropriate for almost totally unmapped areas.  Let's be sure that people
are not talking past each other: any 'import' or 'bulk import' would have to
be done with caution and plenty of checks against existing data, only adding
new information where it is clearly missing.  I think everyone accepts that.

Perhaps one rule of thumb would be not to import any building from OS within
100 metres of an existing building on the map.  The 'gaps' could be filled in
later with manual assistance.

Where it gets more interesting is when OS geometry differs slightly from our
own.  If the OS buildings were simply copied they could end up overlapping
streets.  Some subtle kind of warping might be needed to shift coordinates by
a metre or two so that the relative position of the building relative to the
roads is preserved.  (I would estimate that the precision of existing OSM
geometry is not more than that, given that GPSes give at best 2m precision
under ideal conditions and the aerial photos are not always perfectly aligned.)

-- 
Ed Avis 


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Re: [Talk-GB] building shapes from OS Street View

[Ed Avis]

Andy Allan  writes:

>I hope you have seen the vast tracts of London that have building
>outlines in OSM already - all of much higher detail than Street View?

I don't know about you, but for me the OS building outlines appear to be of far
higher detail than I can map myself by surveying or by tracing from the
relatively low-resolution, not-quite-overhead aerial photos available to OSM.

-- 
Ed Avis 


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Re: [Talk-GB] building shapes from OS Street View

[Dave Stubbs]

On Tue, Apr 6, 2010 at 6:14 PM, Henry Gomersall  wrote:
> On Tue, 2010-04-06 at 18:07 +0100, Dave Stubbs wrote:
>> Basically: please don't break the map :-)
>
> perhaps a stupid question... Is there no version control? I couldn't
> find anything on the wiki about it.
>

Sure.

But if you go and import everything, and I go and unimport everything,
that's not much fun for either of us.

Dave

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Re: [Talk-GB] building shapes from OS Street View

[Henry Gomersall]

On Tue, 2010-04-06 at 18:07 +0100, Dave Stubbs wrote:
> Basically: please don't break the map :-)

perhaps a stupid question... Is there no version control? I couldn't
find anything on the wiki about it.


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Re: [Talk-GB] building shapes from OS Street View

[Dave Stubbs]

On Tue, Apr 6, 2010 at 5:26 PM, TimSC  wrote:
> Andy Allan wrote:
>> On Tue, Apr 6, 2010 at 12:46 PM, TimSC  wrote:
>>
>>> If we use only manual surveying, we can only
>>> achieve coverage of about 1%. I don't think that is satisfactory. Imports
>>> are therefore very much appropriate for buildings.
>>>
>>
>> You're missing the point on several levels. For buildings it's quite
>> possible to trace the outlines from aerial imagery, where we have it.
>> And in some parts of the country, we have better imagery than the
>> building outlines shown on Street View - yahoo, and soon the Surrey
>> imagery, for starters. So it's not a case of Street View or nothing. I
>> hope you have seen the vast tracts of London that have building
>> outlines in OSM already - all of much higher detail than Street View?
>>
> It's not vast, it doesn't even get to the edge of the underground zone
> 1. And the detail is comparable to my eye, except for many omissions in
> OSM. I am not sure how you are quantifying quality. I suspect that the
> OSM data is more up to date (even if Yahoo is a few years out of date),
> but OSM still very incomplete even in this supposedly well mapped area.
> I suspect with the few OSM contributors doing tracing the various
> sources and given their limited coverage, we are still looking like
> converging on poor overall coverage given years of effort, so my
> original point still stands. I say we can compliment our other sources
> with automatic tracing (be that by importing or editor tools).
>
> I guess the question is how much progress can we make on building
> outlines over different time scales, given different approaches?
>> If you are not talking
>> about "bulk imports" then please don't call your ideas imports,
>> otherwise you confuse people as to your intentions.
> I am discussing automatic tracing which applies to both editor tools and
> imports. There is no rule that I have to discuss one option exclusively.
> But I was leaning towards more the import paradigm, while the majority
> seems to be for editor tools. Andy, from my perspective, you have not
> given a single justified reason against doing imports, so I can't really
> rebut your position (although other people have made valid points). I
> suggest you get a bit more constructive and outline your vision for the
> way ahead on this issue? Continue, as is, with Yahoo and so on?
>

The thing we're looking to not have is automatic imports. London has a
lot of buildings, but only in certain areas. What I don't want to have
to do is wake up one morning to discover someone has helpfully
imported auto-detected rectangles over the top, meaning I have to
spend the next three days/years cleaning up the data. If all you want
to do is load some buildings into an area (however that's
implemented), fix it up to avoid duplicates and conflicts with
existing data such as roads, and upload that, then fine. If you want
to spend the time comparing against other sources too then even
better.

If you want to dump buildings into the entire country and hope that
everybody gets around to fixing all the problems in their area
afterwards, then please don't.

Basically: please don't break the map :-)
Other than that, tracing OS street view is by far the best source of
building outlines we will have in much of the UK at the moment.

Dave

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Re: [Talk-GB] building shapes from OS Street View

[TimSC]

Andy Allan wrote:
> On Tue, Apr 6, 2010 at 12:46 PM, TimSC  wrote:
>   
>> If we use only manual surveying, we can only
>> achieve coverage of about 1%. I don't think that is satisfactory. Imports
>> are therefore very much appropriate for buildings.
>> 
>
> You're missing the point on several levels. For buildings it's quite
> possible to trace the outlines from aerial imagery, where we have it.
> And in some parts of the country, we have better imagery than the
> building outlines shown on Street View - yahoo, and soon the Surrey
> imagery, for starters. So it's not a case of Street View or nothing. I
> hope you have seen the vast tracts of London that have building
> outlines in OSM already - all of much higher detail than Street View?
>   
It's not vast, it doesn't even get to the edge of the underground zone 
1. And the detail is comparable to my eye, except for many omissions in 
OSM. I am not sure how you are quantifying quality. I suspect that the 
OSM data is more up to date (even if Yahoo is a few years out of date), 
but OSM still very incomplete even in this supposedly well mapped area. 
I suspect with the few OSM contributors doing tracing the various 
sources and given their limited coverage, we are still looking like 
converging on poor overall coverage given years of effort, so my 
original point still stands. I say we can compliment our other sources 
with automatic tracing (be that by importing or editor tools).

I guess the question is how much progress can we make on building 
outlines over different time scales, given different approaches?
> If you are not talking
> about "bulk imports" then please don't call your ideas imports,
> otherwise you confuse people as to your intentions. 
I am discussing automatic tracing which applies to both editor tools and 
imports. There is no rule that I have to discuss one option exclusively. 
But I was leaning towards more the import paradigm, while the majority 
seems to be for editor tools. Andy, from my perspective, you have not 
given a single justified reason against doing imports, so I can't really 
rebut your position (although other people have made valid points). I 
suggest you get a bit more constructive and outline your vision for the 
way ahead on this issue? Continue, as is, with Yahoo and so on?

Robert's point was along the lines I am thinking along:

> My preferred solution would be doing a country-wide generation of a 
> buildings.osm which users can merge from. Hence no need for special plugins 
> or tools to be distributed to regular contributors.
>   
I would think this takes less effort than a JOSM map processor plugin 
and also result in a better quality conversion due to the rectification 
artifacts I mentioned in my previous post. Who is the technical expert 
on the Street View rectification? Any comments on that issue?

TimSC


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Re: [Talk-GB] building shapes from OS Street View

[Andy Allan]

On Tue, Apr 6, 2010 at 1:22 PM, Robert Scott  wrote:

>  I'd say about 95% of buildings are rectangles. About 99% of buildings are 
> purely orthogonal lines.

We need to be careful about extracting shapes from products that are
known to be downsampled. A quick look at Street View in my area shows
that OSM has more detail in the building outlines than Street View,
suggesting to me that MasterMap outlines have been simplified (often
to rectangles) to make this particular product.

We need to realise that whilst we map to a high level of detail and
keep those details in our end products, the OS don't and often have
simplified outputs. So it's a false assumption that the buildings in
Street View are accurate or better than OSM can create by other means.

Cheers,
Andy

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Re: [Talk-GB] building shapes from OS Street View

[Andy Allan]

On Tue, Apr 6, 2010 at 12:46 PM, TimSC  wrote:

> In response to the comment "no imports ever", I would point out that
> building imports is a completely different situation than that of public
> roads. A glance at OS Street View suggests that about 99% of buildings are
> not publically accessible. If we use only manual surveying, we can only
> achieve coverage of about 1%. I don't think that is satisfactory. Imports
> are therefore very much appropriate for buildings.

You're missing the point on several levels. For buildings it's quite
possible to trace the outlines from aerial imagery, where we have it.
And in some parts of the country, we have better imagery than the
building outlines shown on Street View - yahoo, and soon the Surrey
imagery, for starters. So it's not a case of Street View or nothing. I
hope you have seen the vast tracts of London that have building
outlines in OSM already - all of much higher detail than Street View?
None of this depends on whether the building is publicly accessible.

Also, you are confusing the use of multiple sources for editing (GPS,
aerial, maps), with that of importing. Imports is an orthogonal
discussion to that of whether the building outlines in Street View are
useful. Please don't confuse the two issues. If you are not talking
about "bulk imports" then please don't call your ideas imports,
otherwise you confuse people as to your intentions. There are people
who are supportive of imagery recognition to help editors, who are
strongly opposed to bulk imports.

Cheers,
Andy

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Re: [Talk-GB] building shapes from OS Street View

[Russ Phillips]

On 6 April 2010 12:46, TimSC  wrote:
>
> Hi again,
>
> Thanks for the feedback on building traces. The consensus seems to be
> for a JOSM plugin while others saying all surveying should be done on
> the ground.

Personally, I'd be happy to see a JOSM plugin similar to the Lakewalker plugin:
http://wiki.openstreetmap.org/wiki/Lakewalker

For those not familiar with it, you activate it, then click on a lake
or similar. The plugin creates a way around the lake, which can then
be manually checked/corrected before the edits are uploaded to OSM.

Russ

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Re: [Talk-GB] building shapes from OS Street View

[Robert Scott]

On Tuesday 06 April 2010, TimSC wrote:
> Regarding the technical difficulty, it remains to be seen if automatic 
> tracing is possible and of sufficient quality. But it is presumptuous to 
> assume it is impossible at this stage.

I want to put my oar in for finding a consensus that we will get the best 
consistent results from automatic tracing of the raster. I don't think it is a 
particularly hard problem. From the looks of it (take these numbers with a 
pinch of salt), I'd say about 95% of buildings are rectangles. About 99% of 
buildings are purely orthogonal lines. We can gain a lot from hunting for 
corners and snapping to orthogonals. This is a vastly simplified subset of the 
raster to vector problem.

My preferred solution would be doing a country-wide generation of a 
buildings.osm which users can merge from. Hence no need for special plugins or 
tools to be distributed to regular contributors.

The tile boundary situation is still an open problem though. Unless someone has 
a machine with terabytes of memory ;)?


robert.

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[Talk-GB] building shapes from OS Street View

[TimSC]

Hi again,

Thanks for the feedback on building traces. The consensus seems to be 
for a JOSM plugin while others saying all surveying should be done on 
the ground. Surveys are only practical where there is permissive or 
public access to buildings, but the majority of buildings are 
inaccessible to the public. Therefore, we need a source besides us doing 
the survey, assuming we want building outlines at all. I think building 
outlines would be useful for navigation, planning, analysis and many 
other uses of the map data.

In response to the comment "no imports ever", I would point out that 
building imports is a completely different situation than that of public 
roads. A glance at OS Street View suggests that about 99% of buildings 
are not publically accessible. If we use only manual surveying, we can 
only achieve coverage of about 1%. I don't think that is satisfactory. 
Imports are therefore very much appropriate for buildings.

The point that buildings may need local knowledge for a high quality 
import is a better point against a mass import. But again, local 
knowledge only really applies to the minority of buildings that are 
accessible. The vast majority of the data can't be improved by local 
knowledge. I suggest the minority of buildings that can be improved can 
be done once they have been imported into the OSM database.

Regarding the technical difficulty, it remains to be seen if automatic 
tracing is possible and of sufficient quality. But it is presumptuous to 
assume it is impossible at this stage.

I observed there are slight artifacts in the rectified tiles with are 
not present in the original set (link below). Notice the "a" in stag is 
distorted and also some of the letters in "Court". An attempt to 
automatically trace those tiles would end up with noticeable glitches. 
Until that stuff gets ironed out, a JOSM plugin, which would presumably 
grab these tiles via WMS, would have poor automatic tracing performance.
http://grant.dev.openstreetmap.org/os-streetview-tiles/17/65322/43740.png

Also the rectified tiles seem to be not the highest zoom level 
available? Having the highest resolution makes automatic tracing much 
more accurate. There are various service roads that are on the OS 
opendata site (search for SU986502) that are not in the rectified tiles:
http://grant.dev.openstreetmap.org/os-streetview-tiles/17/65322/43739.png

One option is to automatically trace objects from the original images 
and then transform the polygons into WGS84. The main thing I am missing 
is an practical (and open) OSTN02 implementation (in python). I will 
investigate this and perhaps trial it in my local area.

One question, is this data set going to be maintained by OS in the 
future? And don't worry, I won't be doing a mass import without a great 
deal of work and discussion.

TimSC


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Re: [Talk-GB] building shapes from OS Street View

[Simon Ward]

On Mon, Apr 05, 2010 at 05:57:16PM +0100, TimSC wrote:
> I was looking at the available OS data and one of the things they have 
> but is not really in the current OSM database is building shapes.

That depends on the area I guess.

> Individual buildings appear in the Street View data. The VectorMap 
> District data seems to focus on land use and only has "important" 
> buildings. The Street View data is much more complete in terms of 
> individual buildings. I guess the questions we have to address are: "is 
> this data worth having in OSM?" and "are there any better sources of 
> building outline?" I think it would be a valuable addition for highly 
> detailed mapping of urban areas, campuses, etc.

Having looked at some of the StreetView data aroud my area, it is not
very accurate at all (probably out of date).

This isn’t something we can just blindly import, trace, or otherwise use
and assume it’s of better quality.

Simon
-- 
A complex system that works is invariably found to have evolved from a
simple system that works.—John Gall


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Re: [Talk-GB] building shapes from OS Street View

[Gregory]

An example of the StreetView building quality:
http://edgemaster.dev.openstreetmap.org/streetview_tiles/ossv.html?zoom=16&lat=54.76441&lon=-1.58318&layers=BTF
The West side of St Aidan's College curves round, but (as you can see on
OSM) it actually curves with sharp angles so each bedroom still has a flat
wall. It's important to have this local knowledge, I've heard the building
is supposed to be the fingers of God curved round and holding the chapel
that didn't get built in the middle.

But surrounding buildings I could trace. Van Mildert College I lost my GPS
traces for. Durham Business School I'm just too lazy to go around but could
later give it a quick check that OS was correct. Then there are places like
Durham Cathedral (a bit North, across the river) which I don't have access
to walk round the whole perimeter, plus the GPS signal gets terrible against
the tall stone walls.

We are all coming to the same conclusion. This stuff will be great for
tracing where the mapper has local knowledge (or is verifying it, maybe via
a GPS-less friend/relative).

It's like lakes and Yahoo! imagery. I map the paths in a park, but I don't
want to walk across the grass and get the pond outline (possibly along a
muddy/dangerous bank in parts) as it would confuse my traces. Instead I
trace the imagery and align it up to the footpaths I added, knowing at what
sections I went next to the water and where there was an island but tree
cover makes it look connected.


On 5 April 2010 13:28, Richard Bullock  wrote:

>
> > I don't think the "we shouldn't sully OSM with OS data" argument stands
> up
> > as looking at my area (Devon) most of the coastline + almost all names of
> > natural features and numerous other stuff has come from the NPE and 1st
> > Edition maps.  The StreetView coastline and waterways data is way better
> > than what we currently have here and unless there is better data coming
> in
> > the near future then we should trace this stuff in asap.
>
> The BoundaryLine dataset should contain the mean-high-water and
> mean-low-water coastlines as vector data.
>
> I wouldn't therefore copy the StreetView raster for coastlines.
>
> If we're going to import any of it, something like the coastlines might
> make
> sense (the original coastlines were largely done via import - and there is
> probably no better source - e.g. even areas with Yahoo imagery will only
> show the coast at one particular snapshot in the tide-cycle).
>
>
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-- 
Gregory
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http://www.livingwithdragons.com
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Re: [Talk-GB] building shapes from OS Street View

[OJ W]

On Mon, Apr 5, 2010 at 7:47 PM, Ed Loach  wrote:
> B) use walking papers to add the house numbers.

C: render addr:housename like addr:housenumber ;)

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Re: [Talk-GB] building shapes from OS Street View

[Richard Bullock]

> I don't think the "we shouldn't sully OSM with OS data" argument stands up
> as looking at my area (Devon) most of the coastline + almost all names of
> natural features and numerous other stuff has come from the NPE and 1st
> Edition maps.  The StreetView coastline and waterways data is way better
> than what we currently have here and unless there is better data coming in
> the near future then we should trace this stuff in asap.

The BoundaryLine dataset should contain the mean-high-water and 
mean-low-water coastlines as vector data.

I wouldn't therefore copy the StreetView raster for coastlines.

If we're going to import any of it, something like the coastlines might make 
sense (the original coastlines were largely done via import - and there is 
probably no better source - e.g. even areas with Yahoo imagery will only 
show the coast at one particular snapshot in the tide-cycle). 


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Re: [Talk-GB] building shapes from OS Street View

[Andy Robinson (blackadder-lists)]

Kevin Peat wrote:
>Sent: 05 April 2010 7:50 PM
>To: David Earl; Talk-GB@openstreetmap.org
>Subject: Re: [Talk-GB] building shapes from OS Street View
>
>In the absence of vector data I agree that a controlled way of auto-tracing
>the building outlines (a JOSM plug-in would be ideal for me) is the way to
>go.

But what is the point of just doing building=yes. Does that really add to
OSM? Surely tracing buildings (with aids or not) would be better associated
with address data inclusion rather than just making a pretty map?

>
>For my area, unless something like this comes along there will never be
>building outlines in OSM as the local demographics mean mappers are in
>short supply and I can't imagine that those that there are would want to
>manually trace 10s of thousands of buildings anyway.
>
>I don't think the "we shouldn't sully OSM with OS data" argument stands up
>as looking at my area (Devon) most of the coastline + almost all names of
>natural features and numerous other stuff has come from the NPE and 1st
>Edition maps.  The StreetView coastline and waterways data is way better
>than what we currently have here and unless there is better data coming in
>the near future then we should trace this stuff in asap.

Which is fine in the absence of anything else, or dedicated mappers on the
ground. Eventually mappers will visit those areas and improve them, I
regularly do and I'm often removing the NPE tags because I have a better
source or an actual tracklog.

Cheers

Andy

>
>Kevin
>
>
>
>
>
>
>
>On 5 April 2010 19:14, David Earl  wrote:
>
>
>   On 05/04/2010 18:41, Graham Jones wrote:
>   > I would like to see a plugin for josm that takes a raster input
>   > (landsat, yahoo, StreetView) and processes it into 'draft' ways
>around
>   > areas of constant(ish) colour - the user then tidies it up and
tags
>it
>   > before uploading (ie I would be very wary of a 'blind' import!).
>
>
>   On 05/04/2010 18:52, Robert Scott wrote:
>> What about supervised 'imports', using a josm/potlatch plugin
>
>
>   Much, much better IMO. I dread the idea of any automated imports for
>the
>   UK into OSM. Tools to automate tracing while being manually aware of
>   what is already there and the flaws in the automation is so much
>better
>   than trying to import and screwing up what's already there,
>duplicating
>   stuff and adding poor quality automation flaws.
>
>   David
>
>
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>
>No virus found in this incoming message.
>Checked by AVG - www.avg.com
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>07:32:00
>



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Re: [Talk-GB] building shapes from OS Street View

[Andy Robinson (blackadder-lists)]

Ed Loach wrote:
>Sent: 05 April 2010 7:48 PM
>To: David Earl; Graham Jones
>Cc: TimSC; talk-gb@openstreetmap.org
>Subject: Re: [Talk-GB] building shapes from OS Street View
>
>While I tweeted a couple of days ago that the shape of our house is wrong
>on Streetview, I do want to
>A) trace the simplified rectangles a street at a time.
>B) use walking papers to add the house numbers.
>I see this as probably quicker and even with simplified shapes better
>results than me stopping by every house and adding a custom text waypoint
>with text of house number (osmmapper), as I canwrite while walking rather
>than stopping for hopefully best possible GPS fix.
>
>I wouldn't locally want building outlines locally for streets I haven't got
>lined up to house number by foot, as it would make keeping track of
>progress harder.
>

I can see myself doing this. I also think it will encourage folks to go out
at collect street data. A building block even a badly drawn one, is still
better than no block at all.


>Sent from my HTC
>
>-Original Message-
>From: David Earl 
>Sent: 05 April 2010 19:14
>To: Graham Jones 
>Cc: TimSC ; talk-gb@openstreetmap.org
>Subject: Re: [Talk-GB] building shapes from OS Street View
>
>On 05/04/2010 18:41, Graham Jones wrote:
>> I would like to see a plugin for josm that takes a raster input
>> (landsat, yahoo, StreetView) and processes it into 'draft' ways around
>> areas of constant(ish) colour - the user then tidies it up and tags it
>> before uploading (ie I would be very wary of a 'blind' import!).
>
>On 05/04/2010 18:52, Robert Scott wrote:
> > What about supervised 'imports', using a josm/potlatch plugin
>
>Much, much better IMO. I dread the idea of any automated imports for the
>UK into OSM. Tools to automate tracing while being manually aware of
>what is already there and the flaws in the automation is so much better
>than trying to import and screwing up what's already there, duplicating
>stuff and adding poor quality automation flaws.
>
>David
>
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>Checked by AVG - www.avg.com
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>07:32:00


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Re: [Talk-GB] building shapes from OS Street View

[Kevin Peat]

In the absence of vector data I agree that a controlled way of auto-tracing
the building outlines (a JOSM plug-in would be ideal for me) is the way to
go.

For my area, unless something like this comes along there will never be
building outlines in OSM as the local demographics mean mappers are in short
supply and I can't imagine that those that there are would want to manually
trace 10s of thousands of buildings anyway.

I don't think the "we shouldn't sully OSM with OS data" argument stands up
as looking at my area (Devon) most of the coastline + almost all names of
natural features and numerous other stuff has come from the NPE and 1st
Edition maps.  The StreetView coastline and waterways data is way better
than what we currently have here and unless there is better data coming in
the near future then we should trace this stuff in asap.

Kevin






On 5 April 2010 19:14, David Earl  wrote:

> On 05/04/2010 18:41, Graham Jones wrote:
> > I would like to see a plugin for josm that takes a raster input
> > (landsat, yahoo, StreetView) and processes it into 'draft' ways around
> > areas of constant(ish) colour - the user then tidies it up and tags it
> > before uploading (ie I would be very wary of a 'blind' import!).
>
> On 05/04/2010 18:52, Robert Scott wrote:
>  > What about supervised 'imports', using a josm/potlatch plugin
>
> Much, much better IMO. I dread the idea of any automated imports for the
> UK into OSM. Tools to automate tracing while being manually aware of
> what is already there and the flaws in the automation is so much better
> than trying to import and screwing up what's already there, duplicating
> stuff and adding poor quality automation flaws.
>
> David
>
> ___
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Re: [Talk-GB] building shapes from OS Street View

[Ed Loach]

While I tweeted a couple of days ago that the shape of our house is wrong on 
Streetview, I do want to 
A) trace the simplified rectangles a street at a time.
B) use walking papers to add the house numbers.
I see this as probably quicker and even with simplified shapes better results 
than me stopping by every house and adding a custom text waypoint with text of 
house number (osmmapper), as I canwrite while walking rather than stopping for 
hopefully best possible GPS fix.

I wouldn't locally want building outlines locally for streets I haven't got 
lined up to house number by foot, as it would make keeping track of progress 
harder.

Sent from my HTC

-Original Message-
From: David Earl 
Sent: 05 April 2010 19:14
To: Graham Jones 
Cc: TimSC ; talk-gb@openstreetmap.org
Subject: Re: [Talk-GB] building shapes from OS Street View

On 05/04/2010 18:41, Graham Jones wrote:
> I would like to see a plugin for josm that takes a raster input
> (landsat, yahoo, StreetView) and processes it into 'draft' ways around
> areas of constant(ish) colour - the user then tidies it up and tags it
> before uploading (ie I would be very wary of a 'blind' import!).

On 05/04/2010 18:52, Robert Scott wrote:
 > What about supervised 'imports', using a josm/potlatch plugin

Much, much better IMO. I dread the idea of any automated imports for the 
UK into OSM. Tools to automate tracing while being manually aware of 
what is already there and the flaws in the automation is so much better 
than trying to import and screwing up what's already there, duplicating 
stuff and adding poor quality automation flaws.

David

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Re: [Talk-GB] building shapes from OS Street View

[David Earl]

On 05/04/2010 18:41, Graham Jones wrote:
> I would like to see a plugin for josm that takes a raster input
> (landsat, yahoo, StreetView) and processes it into 'draft' ways around
> areas of constant(ish) colour - the user then tidies it up and tags it
> before uploading (ie I would be very wary of a 'blind' import!).

On 05/04/2010 18:52, Robert Scott wrote:
 > What about supervised 'imports', using a josm/potlatch plugin

Much, much better IMO. I dread the idea of any automated imports for the 
UK into OSM. Tools to automate tracing while being manually aware of 
what is already there and the flaws in the automation is so much better 
than trying to import and screwing up what's already there, duplicating 
stuff and adding poor quality automation flaws.

David

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Re: [Talk-GB] building shapes from OS Street View

[Robert Scott]

On Monday 05 April 2010, Andy Allan wrote:
> > Any general thoughts on buildings and imports?
> 
> Don't import stuff. I'll be happy to see you import things that you
> are willing, personally, to maintain and update, and I'd prefer you
> imported using Potlatch or JOSM and used the Street View, Yahoo, GPS
> and local knowledge all mixed in as your sources. But no bulk imports
> of automatically generated buildings please.

What about supervised 'imports', using a josm/potlatch plugin (a la 
cadastre-fr) to do vectorization and manually merging the results street by 
street?

What about automatic generation of buildings countrywide to an osm layer that 
users manually merge with osm.org, again, street by street or block by block?

I'm just cowering at the hundreds of thousands of man hours of unnecessary 
clickety-click-click-click that could be hugely accelerated by machine vision 
algorithms.


robert.

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Re: [Talk-GB] building shapes from OS Street View

[Andrew Ainsworth]

I've got a copy of some old 25inch to the mile maps for my area and I've
compared the new StreetView maps with this to see if it's worth tracing
buildings. Almost all the detail of actual building shape is lost in
StreetView with most buildings reduced to a simple rectangle. Some are also
half "missing" as they are covered up with a road which is obviously drawn
on after the buildings are. However it does seem useful for locating the
positions of buildings. I wouldn't have thought it was worth bothering in
most cases.

Another potential source of building shapes is photogrammetry, this is
something I've been trying in the middle of Market Harborough with St
Sionysius which produced some good data. If you want to see exactly what I
did for that take a look at my OSM diary. Incidentally, St Dionysius in
streetview is just a rectangle. For public buildings with good access all
around this is definately a viable data source (if somewhat time intensive
at the moment but we're working on this).

Ainsworth

On 5 April 2010 17:57, TimSC  wrote:

>
> Hi all,
>
> I was looking at the available OS data and one of the things they have
> but is not really in the current OSM database is building shapes.
> Individual buildings appear in the Street View data. The VectorMap
> District data seems to focus on land use and only has "important"
> buildings. The Street View data is much more complete in terms of
> individual buildings. I guess the questions we have to address are: "is
> this data worth having in OSM?" and "are there any better sources of
> building outline?" I think it would be a valuable addition for highly
> detailed mapping of urban areas, campuses, etc.
>
> The other sources of building outlines I know of are the 1st edition OS
> sheets (which are rather old), Yahoo imagery (which takes work to
> trace), and manual surveying (which is a major hassle since buildings
> tend to throw off GPS positions). Another source would be preferable to
> these.
>
> If we do want this data, it seems to be only available as a raster
> layer. (Does anyone know if this will be available as a vector layer?)
> Converting raster map data to vector data is non trivial but I think it
> is achievable. The building colour in the raster map seems to be unique.
> The raster maps could be selected by colour, vectorised and simplified
> (to remove redundant nodes). Since we have a significant number of
> buildings mapped in the UK, we could presume that we don't want to
> overwrite or duplicate what is already there. Buildings could be
> imported if it would not overlap with an existing building in OSM. One
> problem is some buildings are marked as leisure=stadium without a
> building=*. We might end up with duplicates of stadiums, leisure
> centres, churches and so on. Would we want the import to be more
> cautious to prevent this? I won't be importing anything until the
> rectification of Street View is complete (and I get a feel for the
> consensus on the mailing list) but I have demoed most of the method in
> python using the shapely module to do some geometry transforms.
>
> Any general thoughts on buildings and imports? Will this data be
> officially available in vector form at some point?
>
> We don't seem to have much comment on the legal issues and the
> implications of ODbL yet. Do we have a view as to if our attribution is
> sufficient?
>
> Regards,
>
> TimSC
>
>
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Re: [Talk-GB] building shapes from OS Street View

[Graham Jones]

Tim,
I think this is a really good idea, and is one of the main benefits of the
StreetView data.

I have been wondering how to do this, but haven't got far.

I would like to see a plugin for josm that takes a raster input (landsat,
yahoo, StreetView) and processes it into 'draft' ways around areas of
constant(ish) colour - the user then tidies it up and tags it before
uploading (ie I would be very wary of a 'blind' import!).   I think
streetview would be the easiest because of the high contrast - I would like
to see it work for landsat because I am colourblind and can't trace the
outline of woods, and the North Yorkshire moors need some more detail!.

Someone (I think it was Mike DuPont) reported doing this with gdal_contour,
but I haven't tried it yet, and I haven't looked at how to turn this into a
josm plugin.

If I'd thought of it earlier I would have suggested this as a GSoC student
project!

Regards

Graham.

On 5 April 2010 17:57, TimSC  wrote:

>
> Hi all,
>
> I was looking at the available OS data and one of the things they have
> but is not really in the current OSM database is building shapes.
> Individual buildings appear in the Street View data. The VectorMap
> District data seems to focus on land use and only has "important"
> buildings. The Street View data is much more complete in terms of
> individual buildings. I guess the questions we have to address are: "is
> this data worth having in OSM?" and "are there any better sources of
> building outline?" I think it would be a valuable addition for highly
> detailed mapping of urban areas, campuses, etc.
>
> The other sources of building outlines I know of are the 1st edition OS
> sheets (which are rather old), Yahoo imagery (which takes work to
> trace), and manual surveying (which is a major hassle since buildings
> tend to throw off GPS positions). Another source would be preferable to
> these.
>
> If we do want this data, it seems to be only available as a raster
> layer. (Does anyone know if this will be available as a vector layer?)
> Converting raster map data to vector data is non trivial but I think it
> is achievable. The building colour in the raster map seems to be unique.
> The raster maps could be selected by colour, vectorised and simplified
> (to remove redundant nodes). Since we have a significant number of
> buildings mapped in the UK, we could presume that we don't want to
> overwrite or duplicate what is already there. Buildings could be
> imported if it would not overlap with an existing building in OSM. One
> problem is some buildings are marked as leisure=stadium without a
> building=*. We might end up with duplicates of stadiums, leisure
> centres, churches and so on. Would we want the import to be more
> cautious to prevent this? I won't be importing anything until the
> rectification of Street View is complete (and I get a feel for the
> consensus on the mailing list) but I have demoed most of the method in
> python using the shapely module to do some geometry transforms.
>
> Any general thoughts on buildings and imports? Will this data be
> officially available in vector form at some point?
>
> We don't seem to have much comment on the legal issues and the
> implications of ODbL yet. Do we have a view as to if our attribution is
> sufficient?
>
> Regards,
>
> TimSC
>
>
> ___
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-- 
Dr. Graham Jones
Hartlepool, UK
email: grahamjones...@gmail.com
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Re: [Talk-GB] building shapes from OS Street View

[Andy Allan]

On Mon, Apr 5, 2010 at 5:57 PM, TimSC  wrote:
> I guess the questions we have to address are: "is
> this data worth having in OSM?"

Yes

> "are there any better sources of
> building outline?"

OS Mastermap. But since we won't get access to that any time soon

> If we do want this data, it seems to be only available as a raster
> layer.

Yes. So we can trace the areas that we're working on, like we've been
using Yahoo!

> Converting raster map data to vector data is non trivial but I think it
> is achievable.

Ummm

> The building colour in the raster map seems to be unique.
> The raster maps could be selected by colour, vectorised and simplified
> (to remove redundant nodes).

 aaahh

> Buildings could be
> imported

... No. No no no no a thousand times no.

> Any general thoughts on buildings and imports?

Don't import stuff. I'll be happy to see you import things that you
are willing, personally, to maintain and update, and I'd prefer you
imported using Potlatch or JOSM and used the Street View, Yahoo, GPS
and local knowledge all mixed in as your sources. But no bulk imports
of automatically generated buildings please.

Cheers,
Andy

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[Talk-GB] building shapes from OS Street View

[TimSC]

Hi all,

I was looking at the available OS data and one of the things they have 
but is not really in the current OSM database is building shapes. 
Individual buildings appear in the Street View data. The VectorMap 
District data seems to focus on land use and only has "important" 
buildings. The Street View data is much more complete in terms of 
individual buildings. I guess the questions we have to address are: "is 
this data worth having in OSM?" and "are there any better sources of 
building outline?" I think it would be a valuable addition for highly 
detailed mapping of urban areas, campuses, etc.

The other sources of building outlines I know of are the 1st edition OS 
sheets (which are rather old), Yahoo imagery (which takes work to 
trace), and manual surveying (which is a major hassle since buildings 
tend to throw off GPS positions). Another source would be preferable to 
these.

If we do want this data, it seems to be only available as a raster 
layer. (Does anyone know if this will be available as a vector layer?) 
Converting raster map data to vector data is non trivial but I think it 
is achievable. The building colour in the raster map seems to be unique. 
The raster maps could be selected by colour, vectorised and simplified 
(to remove redundant nodes). Since we have a significant number of 
buildings mapped in the UK, we could presume that we don't want to 
overwrite or duplicate what is already there. Buildings could be 
imported if it would not overlap with an existing building in OSM. One 
problem is some buildings are marked as leisure=stadium without a 
building=*. We might end up with duplicates of stadiums, leisure 
centres, churches and so on. Would we want the import to be more 
cautious to prevent this? I won't be importing anything until the 
rectification of Street View is complete (and I get a feel for the 
consensus on the mailing list) but I have demoed most of the method in 
python using the shapely module to do some geometry transforms.

Any general thoughts on buildings and imports? Will this data be 
officially available in vector form at some point?

We don't seem to have much comment on the legal issues and the 
implications of ODbL yet. Do we have a view as to if our attribution is 
sufficient?

Regards,

TimSC


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