[Talk-GB] OS 7th Series offset

Andy Robinson (blackadder-lists) ajrlists at googlemail.com
Wed Oct 7 10:07:33 BST 2009


Christopher,

Useful sanity check, thanks.

Looking at the the OSTN02 FAQ it states:

"While it is true that two adjacent OSGB36 triangulation stations are
usually in agreement with each other to within a few centimetres, if we
compare two triangulation stations 10 km apart by measuring a precise GPS
vector, we will typically find an error of several decimetres in their
relative archive coordinates. If the two stations are 100 km apart, the
relative error between them might be four metres. If the stations are at
opposite ends of the country, we will find a twenty metre relative error
between the two, based on their archive OSGB36 coordinates."

This would suggest that the error in a position of a 10km x 10km 1:25k map
sheet is in the order of centimetres rather than meters. And furthermore the
OS PAI process found errors only of a less than 5m maximum I think. So I
assume that although these errors are important for precise surveying they
probably don't impact OSM that much? Obviously the error would be
exaggerated over a bigger sheet such as the 7th series but presumably
provided sufficient control points are used the error isn't going to be
significant.

Thoughts?

Cheers

Andy

>-----Original Message-----
>From: talk-gb-bounces at openstreetmap.org [mailto:talk-gb-
>bounces at openstreetmap.org] On Behalf Of Christopher Osborne
>Sent: 07 October 2009 9:05 AM
>To: talk-gb at openstreetmap.org
>Subject: [Talk-GB] OS 7th Series offset
>
>Regarding the offset Shaun observed - the OS carried out a retriangulation
>exercise that only finished in 1962. I've been off list for a while so
>excuse me if I'm incorrect, but these are 50 year old out of copyright maps
>from 1959 before retriangulation finished?
>
>Further you are away from the datum origin the bigger the error incurred,
>so may explain the offset for the Scottish scans?
>
>You are probably already ahead of me and compensated but OSTN02 is a
>transformation which is supposed to deal with this.
>
>Great work Steve et al
>
>Christopher Osborne
>www.itoworld.com
>07533 188 262
>
>	On Oct 6, 2009 9:49 PM, <talk-gb-request at openstreetmap.org> wrote:
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>	Today's Topics:
>
>	  1. Re: Royal Mail lawyers demand closure of postcode lookup  site
>	     (OJ W)
>	  2. Re: Royal Mail lawyers demand closure of postcode lookup  site
>	     (Peter Childs)
>	  3. Announcement - OS 1:25k mapping availability for OSM data
>	     contributors (Andy Robinson (blackadder-lists))
>	  4. Re: Announcement - OS 1:25k mapping availability for OSM  data
>	     contributors (Andy Robinson (blackadder-lists))
>	  5. Re: Royal Mail lawyers demand closure of postcode lookup  site
>	     (Jason Cunningham)
>	  6. Ordnance Survey 7th series available (Steve Chilton)
>	  7. Re: Ordnance Survey 7th series available (Frankie Roberto)
>	  8. Re: Ordnance Survey 7th series available (Shaun McDonald)
>
>
>
---------------------------------------------------------------------
>-
>
>	Message: 1
>	Date: Tue, 6 Oct 2009 14:08:13 +0100
>	From: OJ W <ojwlists at googlemail.com>
>	Subject: Re: [Talk-GB] Royal Mail lawyers demand closure of postcode
>	       lookup  site
>	To: osm-gb <talk-gb at openstreetmap.org>
>	Message-ID:
>	       <89699a0a0910060608r450ed5c9r1d899ad99204e67b at mail.gmail.com>
>	Content-Type: text/plain; charset=ISO-8859-1
>
>	First strike! [jobcentre-plus seem to have been using this data].
>Two
>	more, and we should cut-off the government's internet connection ;)
>
>
>	On Tue, Oct 6, 2009 at 11:10 AM, David Earl
><david at frankieandshadow.com> wrote:
>	>
>http://www.theregister.co.uk/2009/10/06/royal_mail_ernest_marples_postcodes
>/
>
>
>
>	------------------------------
>
>	Message: 2
>	Date: Tue, 6 Oct 2009 14:24:23 +0100
>	From: Peter Childs <pchilds at bcs.org>
>	Subject: Re: [Talk-GB] Royal Mail lawyers demand closure of postcode
>	       lookup  site
>	To: OJ W <ojwlists at googlemail.com>
>	Cc: osm-gb <talk-gb at openstreetmap.org>
>	Message-ID:
>	       <a2de01dd0910060624v65e45250s483434b6b0395898 at mail.gmail.com>
>	Content-Type: text/plain; charset=ISO-8859-1
>
>	2009/10/6 OJ W <ojwlists at googlemail.com>:
>	> First strike! [jobcentre-plus seem to have been using this data].
>?Two
>	> more, and we should cut-off the government's internet connection
;)
>	>
>
>	Actually I think its more along the line of a company that knows its
>	head is on the line.
>
>	The SCO stuff a few years ago spring to mind.
>
>	I'm wondering who has actually made there subscription charge for
>this
>	data, and I wonder how long it will be before loads of Local
Councils
>	are having trouble with Council Tax and deciding which school is the
>	closest.....
>
>	Peter
>
>	>
>	> On Tue, Oct 6, 2009 at 11:10 AM, David Earl
><david at frankieandshadow.com> wrote:
>	>>
>http://www.theregister.co.uk/2009/10/06/royal_mail_ernest_marples_postcodes
>/
>	>
>	> _______________________________________________
>	> Talk-GB mailing list
>	> Talk-GB at openstreetmap.org
>	> http://lists.openstreetmap.org/listinfo/talk-gb
>	>
>
>
>
>	------------------------------
>
>	Message: 3
>	Date: Tue, 6 Oct 2009 15:04:26 +0100
>	From: "Andy Robinson \(blackadder-lists\)" <ajrlists at googlemail.com>
>	Subject: [Talk-GB] Announcement - OS 1:25k mapping availability for
>	       OSM data        contributors
>	To: <talk-gb at openstreetmap.org>
>	Message-ID:
>
><!&!AAAAAAAAAAAuAAAAAAAAAOKaD4mR3JBOrEpRon92nMgBANp/H2q5kHFIvKMsnZiQaZAAAAA
>BxJAAABAAAABBRF9JT8fMSpGg5IzXlaJmAQAAAAA=@googlemail.com>
>
>	Content-Type: text/plain;       charset="iso-8859-1"
>
>	We are all used to drawing in difficult or far away features by
>referring to
>	the NPE 1" to 1 mile out of copyright Ordnance Survey mapping in
JOSM
>or
>	Potlatch. Its great for long linear features but for accurate stuff,
>like
>	field boundaries and detailed information about the landscape,
>especially in
>	rural areas, it's not enough.
>
>	Enter the OS 1:25,000 scale (two and a half inches to the mile)
>	1st/Provisional edition [1]. Which I'm happy to announce is starting
>to make
>	an appearance for the project.
>
>	There are two parts to the availability currently. One focused on
>providing
>	it via WMS for use in JOSM and the other as tiles for Potlatch.
>
>	The first full sheet (NX88 NW or Dumfries [2]) is available for you
>to try
>	out in JOSM [3]. Just add the URL as a custom WMS.
>
>	For the Potlatch tiles RichardF has worked up some code magic that
>should
>	automate the process of rectification and tiling. It may take me a
>little
>	time to get that running and the tiles will probably be served from
>the new
>	dev machine which is not quite ready yet so there will be a further
>	announcement on this.
>
>	Both the WMS and google format tiles use the same rectification
data.
>
>	The time consuming part is manually obtaining the pixel co-ordinates
>for the
>	corner gridlines of each sheet (which I have to scan in two halves
on
>my A3
>	scanner). It has to be done manually to get the best accuracy, which
>should
>	be generally 10m once available in Potlatch or JOSM. i.e.
>significantly
>	better than was possible with NPE, though note that its still only
as
>good
>	as the OS originally survey it in the late 19th century. Anyway, it
>means
>	that this part is a slow process.
>
>	Currently I have around 15% of the published sheets with more
>arriving every
>	day. More would be welcome, either by way of donated maps, scans, or
>funds
>	to purchase more from retail suppliers (higher cost - usually about
>?3 to ?8
>	each). With 2027 sheets in the series cost is a factor for how
>quickly I can
>	grow the set.
>
>	I'll keep the index updated on the wiki with progress (both
obtaining
>and
>	scanning/tiling) so look out for your area turning up. The majority
>of the
>	sheets I have are for England and Wales. Scotland never had full
>coverage
>	from this series.
>
>	Cheers
>
>	Andy
>
>	[1] "http://wiki.openstreetmap.org/wiki/Provisional/First_Edition"
>	[2] "http://osm.org/go/evY0@6R"
>	[3]
>
"http://warper.freemap.in/layers/wms/1?request=GetMap&version=1.1.1&s
>tyles=&
>
format=image/png&srs=epsg:4326&exceptions=application/vnd.ogc.se_inim
>age&
><http://warper.freemap.in/layers/wms/1?request=GetMap&version=1.1.1&styles=
>&
>format=image/png&srs=epsg:4326&exceptions=application/vnd.ogc.se_inimage&>
>"
>
>
>
>
>
>	------------------------------
>
>	Message: 4
>	Date: Tue, 6 Oct 2009 15:07:02 +0100
>	From: "Andy Robinson \(blackadder-lists\)" <ajrlists at googlemail.com>
>	Subject: Re: [Talk-GB] Announcement - OS 1:25k mapping availability
>	       for OSM data contributors
>	To: <talk-gb at openstreetmap.org>
>	Message-ID:
>
><!&!AAAAAAAAAAAuAAAAAAAAAOKaD4mR3JBOrEpRon92nMgBANp/H2q5kHFIvKMsnZiQaZAAAAA
>BxJAAABAAAABEDam69XqSSJsRWqpdr08mAQAAAAA=@googlemail.com>
>
>	Content-Type: text/plain;       charset="iso-8859-1"
>
>	And in my haste I omitted to thank Chippy for his excellent map
>	rectification/warping and WMS facilities. Apologies Tim.
>
>	Cheers
>
>	Andy
>
>	>-----Original Message-----
>	>From: Andy Robinson (blackadder-lists)
>[mailto:ajrlists at googlemail.com]
>	>Sent: 06 October 2009 3:04 PM
>	>To: 'talk-gb at openstreetmap.org'
>	>Subject: Announcement - OS 1:25k mapping availability for OSM data
>	>contributors
>	>
>	>We are all used to drawing in difficult or far away features by
>referring
>	>to the NPE 1" to 1 mile out of copyright Ordnance Survey mapping in
>JOSM or
>	>Potlatch. Its great for long linear features but for accurate
stuff,
>like
>	>field boundaries and detailed information about the landscape,
>especially
>	>in rural areas, it's not enough.
>	>
>	>Enter the OS 1:25,000 scale (two and a half inches to the mile)
>	>1st/Provisional edition [1]. Which I'm happy to announce is
starting
>to
>	>make an appearance for the project.
>	>
>	>There are two parts to the availability currently. One focused on
>providing
>	>it via WMS for use in JOSM and the other as tiles for Potlatch.
>	>
>	>The first full sheet (NX88 NW or Dumfries [2]) is available for you
>to try
>	>out in JOSM [3]. Just add the URL as a custom WMS.
>	>
>	>For the Potlatch tiles RichardF has worked up some code magic that
>should
>	>automate the process of rectification and tiling. It may take me a
>little
>	>time to get that running and the tiles will probably be served from
>the new
>	>dev machine which is not quite ready yet so there will be a further
>	>announcement on this.
>	>
>	>Both the WMS and google format tiles use the same rectification
>data.
>	>
>	>The time consuming part is manually obtaining the pixel
co-ordinates
>for
>	>the corner gridlines of each sheet (which I have to scan in two
>halves on
>	>my A3 scanner). It has to be done manually to get the best
accuracy,
>which
>	>should be generally 10m once available in Potlatch or JOSM. i.e.
>	>significantly better than was possible with NPE, though note that
>its still
>	>only as good as the OS originally survey it in the late 19th
>century.
>	>Anyway, it means that this part is a slow process.
>	>
>	>Currently I have around 15% of the published sheets with more
>arriving
>	>every day. More would be welcome, either by way of donated maps,
>scans, or
>	>funds to purchase more from retail suppliers (higher cost - usually
>about
>	>?3 to ?8 each). With 2027 sheets in the series cost is a factor for
>how
>	>quickly I can grow the set.
>	>
>	>I'll keep the index updated on the wiki with progress (both
>obtaining and
>	>scanning/tiling) so look out for your area turning up. The majority
>of the
>	>sheets I have are for England and Wales. Scotland never had full
>coverage
>	>from this series.
>	>
>	>Cheers
>	>
>	>Andy
>	>
>	>[1] "http://wiki.openstreetmap.org/wiki/Provisional/First_Edition"
>	>[2] "http://osm.org/go/evY0@6R"
>	>[3]
>
>"http://warper.freemap.in/layers/wms/1?request=GetMap&version=1.1.1&
>styles=
>
>&format=image/png&srs=epsg:4326&exceptions=application/vnd.ogc.se_in
>image&"
>
>
>
>
>
>	------------------------------
>
>	Message: 5
>	Date: Tue, 6 Oct 2009 15:16:44 +0100
>	From: Jason Cunningham <jamicuosm at googlemail.com>
>	Subject: Re: [Talk-GB] Royal Mail lawyers demand closure of postcode
>	       lookup  site
>	To: osm-gb <talk-gb at openstreetmap.org>
>	Message-ID:
>	       <897b959f0910060716j5300de97v32adb0a8b4f088f6 at mail.gmail.com>
>	Content-Type: text/plain; charset="iso-8859-1"
>
>	2009/10/6 OJ W <ojwlists at googlemail.com>
>
>	> First strike! [jobcentre-plus seem to have been using this data].
>Two
>	> more, and we should cut-off the government's internet connection
;)
>	>
>
>	Its not the governments jobcentreplus website, its
>www.jobcentreproplus.com
>	(note the pro). Its "a clean rewrite of the Job Centre Plus
>government
>	website, allowing job seekers to quickly and easily find jobs by
>keyword
>	within their local area, and subscribe to email alerts to future
>additions."
>	The site was a good example of why we should have free access to
>postcode
>	data. I came across a link to a presentation they gave at
>	rewirdedstate.org"national hack the government day" -
>	http://blip.tv/file/1853120/
>
>	I wonder if Royal Mail would go after councils and government
>departments
>	who have failed to pay or keep up with their subscriptions. Its
>probably not
>	a good idea to send threatening letters to bodies who could
>successfully
>	lobby for things to be changed.
>
>	Hopefully this might result in some advertising for free-the-
>postcode, and
>	its aims
>
>	Jason
>	-------------- next part --------------
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>	------------------------------
>
>	Message: 6
>	Date: Tue, 06 Oct 2009 20:12:54 +0100
>	From: Steve Chilton <S.L.Chilton at mdx.ac.uk>
>	Subject: [Talk-GB] Ordnance Survey 7th series available
>	To: talk-gb at openstreetmap.org
>	Cc: announce at openstreetmap.org
>	Message-ID:
>	       <ED161E4EC1B411458949EEA28C5590150C0D8172 at MDX-CLX-
>DC1.uni.mdx.ac.uk>
>	Content-Type: text/plain; charset=utf-8
>
>	I am pleased to announce that the first of the OS 7th series out-of-
>copyright maps are available for use in OSM.
>	Very brief details of the sheets and how to access them is available
>on the wiki at
>	http://wiki.openstreetmap.org/wiki/7th_Series
>	Thanks to TimSC for rectification work and setting up for WMS for
>JOSM, and to Richard for the Potlatch link.
>	Those available are just the first of the 23 that are out-of-
>copyright right now, mainly in Scotland. More shortly.
>	This is an ongoing project, and more sheets will be available to use
>a) as they come out of copyright, and b) are rectified and tiled.
>	Any problems please contact me.
>
>	Cheers
>	STEVE
>
>
>
>	------------------------------
>
>	Message: 7
>	Date: Tue, 6 Oct 2009 21:24:11 +0100
>	From: Frankie Roberto <frankie at frankieroberto.com>
>	Subject: Re: [Talk-GB] Ordnance Survey 7th series available
>	To: Steve Chilton <S.L.Chilton at mdx.ac.uk>
>	Cc: talk-gb at openstreetmap.org
>	Message-ID:
>	       <1350f7a40910061324s3202cb4n637b1cdb37c375ba at mail.gmail.com>
>	Content-Type: text/plain; charset="utf-8"
>
>	2009/10/6 Steve Chilton <S.L.Chilton at mdx.ac.uk>
>
>	I am pleased to announce that the first of the OS 7th series
>	> out-of-copyright maps are available for use in OSM.
>	> Very brief details of the sheets and how to access them is
>available on the
>	> wiki at
>	> http://wiki.openstreetmap.org/wiki/7th_Series
>	>
>
>	Wow, they are beautiful maps!
>
>	I've just had a go at using them as a background in Potlatch,
looking
>at
>	Campbeltown. There are plenty of roads on the map that aren't on
OSM.
>Is it
>	reasonably safe to assume that these probably do still exist, and
can
>be
>	added to OSM (with appropriate source tag?)
>
>	Frankie
>
>	--
>	Frankie Roberto
>	Experience Designer, Rattle
>	0114 2706977
>	http://www.rattlecentral.com
>	-------------- next part --------------
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>	------------------------------
>
>	Message: 8
>	Date: Tue, 6 Oct 2009 21:36:05 +0100
>	From: Shaun McDonald <shaun at shaunmcdonald.me.uk>
>	Subject: Re: [Talk-GB] Ordnance Survey 7th series available
>	To: Frankie Roberto <frankie at frankieroberto.com>
>	Cc: talk-gb at openstreetmap.org, Steve Chilton <S.L.Chilton at mdx.ac.uk>
>	Message-ID: <1AD83A27-1032-4CB5-8125-
>1B798010BB3D at shaunmcdonald.me.uk>
>	Content-Type: text/plain; charset="us-ascii"
>
>
>	On 6 Oct 2009, at 21:24, Frankie Roberto wrote:
>
>	> 2009/10/6 Steve Chilton <S.L.Chilton at mdx.ac.uk>
>	>
>	> I am pleased to announce that the first of the OS 7th series out-
>of-
>	> copyright maps are available for use in OSM.
>	> Very brief details of the sheets and how to access them is
>available
>	> on the wiki at
>	> http://wiki.openstreetmap.org/wiki/7th_Series
>	>
>	> Wow, they are beautiful maps!
>	>
>	> I've just had a go at using them as a background in Potlatch,
>	> looking at Campbeltown. There are plenty of roads on the map that
>	> aren't on OSM.  Is it reasonably safe to assume that these
probably
>	> do still exist, and can be added to OSM (with appropriate source
>tag?)
>	>
>
>	Press b in Potlatch to get the source tag added.
>
>	I have noticed that the status of some of the roads seem to have
>	changed in Dumfries, so I think that local knowledge would be useful
>	for this one.
>
>	I've noticed that there is an offset in Dumfries that is noticeable
>	(the current data is based on GPS). I've not checked to see how
>	widespread the problem is.
>
>	Shaun
>
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