[Talk-GB] NLS historical OS plans for grid square TQ

[Ken Kilfedder]

This is great news, many thanks for making contact with NLS and getting the maps into JOSM.

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https://hdyc.neis-one.org/?spiregrain
spiregrain_osm at ksglp.org.uk

On Mon, 26 Dec 2022, at 10:49 PM, Adrian via Talk-GB wrote:
> I have been in touch with Chris Fleet, the curator of maps at the 
> National Library of Scotland. He has confirmed that the historical 
> Ordnance Survey maps of London and south-east England at 1:1250 and 
> 1:2500 are now available for use in OSM. I have added an entry for 
> these maps in the wiki [1]. I have added the maps to the list of 
> imagery sources used by JOSM (because it was straightforward to do). I 
> have not added them to the Editor Layer Index used by iD etc. [2], 
> because I don't have a Github account and I don't know how to do a pull 
> request.
>
> Note that these maps need to be aligned, using the OSMUK Cadastral 
> Parcels. This is because the NLS has used the Helmert transformation to 
> convert from British National Grid projection to Web Mercator 
> projection. [There is another factor causing misalignment, although it 
> doesn't affect London and south-east England. So, using the look-up 
> table transformation would not be a complete solution to misalignment. 
> This factor is that in some places the OS have *moved their grid lines* 
> by a few metres since the maps were printed. Locations affected include 
> the Scilly Isles, Stornoway and Oban. Maps of Stornoway and Oban are 
> already available from the NLS.]
>
> Chris Fleet also proposed a revamp of the wiki page [1]. I don't think 
> he is aware of the way the calling-up of imagery layers in OSM editors 
> has been simplified/automated.
>
> On 23 December 2022 at 12:17, Fleet, Christopher wrote:
>
> ... This page, though is very dated, and doesn't include a range of 
> other georeferenced maps which may also be useful to OSMers. For 
> example, in the last year, we have put online over 400 OS Town Plans of 
> English and Welsh towns at https://maps.nls.uk/os/townplans-england/ at 
> 1:1500-1:1,056 scales which are not listed, and we've just added 
> potentially useful air photos for England and Wales too 
> https://maps.nls.uk/additions/#134.
>
> I was wondering what you would feel about a wider revamp of that NLS 
> OSM wiki page which pointed to the way that XYZ URLs of all the NLS 
> georeferenced layers can be found following the guide at 
> https://maps.nls.uk/guides/georeferencing/layers-urls/, and then 
> following the guide at https://maps.nls.uk/guides/georeferencing/osm/ 
> for how to bring them into OSM. This would mean that the latest correct 
> URLs for our georeferenced layers were always used, and OSMers could 
> access all the NLS georeferenced layers.
>
> Would be interested in your thoughts on this.
> ------------------------------------------------------------------------
>
> I don't know the history of how the current wiki page was arrived at. 
> And I don't know how the NLS entries in the lists of imagery sources 
> were compiled. So I'm probably not the right person to liaise with 
> Chris Fleet over this. Would someone like to take it up please? (The 
> email address is on the wiki page.)
>
> [1] https://wiki.openstreetmap.org/wiki/National_Library_of_Scotland
> [2] https://github.com/osmlab/editor-layer-index
>
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