Provisional/First Edition
Contents |
Background
The Ordnance Survey 1:25,000 First Series (Provisional Edition) consists of 2027 maps which were printed from the 1940's right through to the 1980's. They were superseded by the Second Edition 1:25,000.
The definitive tome to the series is "A Guide to the Ordnance Survey 1:25,000 First Series" by Roger Hellyer and with an introduction essay by Richard Oliver, published by The Charles Close Society in 2003. ISBN 1-870598-20-2. Blackadder has a copy.
The front cover of the series is basically blue and cream although the exact format varied through the years. Full examples here
Blackadder has been actively collecting out of copyright or near out of copy right editions of this series. Currently (Aug 2011) approximately 66% of the 2027 sheets have been acquired. Thanks to a very large donation from the University of Glasgow (Around 700 sheet numbers plus a great many duplicates, including many different print editions) almost all the sheets for northern England and Scotland (to the extent ever published) are now held and await scanning.
A full index is available as a tabulated list, or as a coloured chart. If you have any you wish to donate please contact Blackadder.
Each sheet and its edition is individually identifiable in the cartobibliography by reference to the following:
- Sheet number - Shown in the bottom left hand corner of the map (and generally also on the cover for folded versions). Initially the first two digits of the sheet number were also numbers, later these were changed to the OS Grid classification system. eg 30/67 became SY67.
- Print edition - Shown just above or below the sheet number in the bottom left corner of the sheet. This is either a number for very early 1940's editions or more commonly as a letter, often with additional underscores and/or asterisks. The book A Guide to the Ordnance Survey 1:25,000 First Series can then be used to verify the publication/copyright status along with other information on the map. See below for an example from the bottom of a sheet.
Relatively few of the sheets have an actual copyright date. Most only have a date at which the print edition was first published and whether it was also reprinted with revision. According to a FOI request to the OS, the copyright expires at the end of the calendar year 50 years after the copyright date, so a map with Crown Copyright (C) 1960 enters the public domain at the start of 2011. For those without a copyright date, further clarification is needed and a new FOI request has been made to obtain this.
Pros
The 1:25,000 scale gives a huge amount of detail that's not available on the 1" maps we have reference to to date. See below for an example. Included are field boundaries for instance
Cons
The First Series was called "Provisional" because it was based on the 6" sheets of the late 19th century. The original intention was to resurvey the land for the new series but this did not happen until the Second series. As a result, other than significant highway additions, these maps have the version of our landscape that existed 100+ years ago.
The Provisional Edition shows many footpaths but they were not designated as Public Rights of Way.
Example Scans
The following scan is from Sheet 30/67 (SY67) and shows the Isle of Portland. The original was scanned at 300dpi but the image size here has been reduced by half to provide a manageable file size of 1MB for the wiki download, but you can also browse it on ooc.openstreetmap.org (with one more zoom level) (NB. The example may take a short period to fully load on some systems, so be patient.)
The following scan shows the sheet number and print edition reference that's found in the bottom left corner of each map. In this instance its B//*
Map Key
This is the generic map key for the series. The key did change a bit over the years but not substantially so.
Scanning
Scanning is being undertaken on Blackadder's own A3 scanner since the sheets will happily scan in two parts. Scanning at 300dpi. Saved as .tif files
Orthorectification & Tiling
Initial calibration of the scans is relatively easy for most of the sheets as distortion is minimal and the position of the OS Grid lines much more accurate than on 1" maps of the same period. Calibration involves obtaining a set of control points in the scanned image. The position of the OSGB grid lines is known on each map so the corners are used plus some additional points as required. I use Photoshop to open the scan and get the xy pixel co-ordinates for each control point. These then go in csv file named the same as the scan image file. The columns used for the perl scrip must be:
Column 1, OSGB Easting in meters Column 2, ignored Column 3, x in pixels Column 4, OSGB Northing in meters Column 5, ignored Column 6, y in pixels
The second and fifth columns are ignored, and can be blank, but do need to be there
Richard has kindly produced a couple of perl scripts (http://svn.openstreetmap.org/applications/utils/ooc/) (tested on OS X and Ubuntu) that do everything else:
First of all, you'll need GDAL and Proj4 installed. Make sure libtiff (libtiff4 in Debian/Ubuntu) is also installed, plus libtiff-tools and libtiff4-dev may also be needed.
You'll then need to install the following Perl modules: - Geo::Proj4 - Imager
as root, do:
perl -MCPAN -e shell
this might ask you a load of questions if you've never used it before. Then, at the command line that appears type:
install Imager install Geo::Proj4 quit
Lots of people in #osm will be able to help you if this doesn't work.
Next put Richard's perl scripts in the directory with your .tif and .CSV files.
Finally, create a new directory called 'tiles' in the same directory.
Straightening the scans
Getting tiles is a two-stage process. The first stage is to straighten up the scans, crop the borders off, and embed the co-ordinates in a new .TIFF file. This is easy, run:
perl georeference.pl filename.csv
You can do a whole bunch at once, so:
perl georeference.pl NX88_001.csv NX88_002.csv
or even
perl georeference.pl *.csv
This'll create straightened files with names like NX88_001_r.tiff ('r' for "rectified"). The .tiff has a four-letter extension.
Reprojecting and tiling
The next stage is to reproject the scans into spherical Mercator ('900913') and chop them up into tiles.
You can't just do this on a per-scan basis. With each scan, you also need to include the scans that border it. Otherwise, because the 900913 tiles are at a different angle than the OSGB ones, you'd end up with blank areas at the edges of the sheet. So make yourself a little list of the scans that border each other.
Then reproject and tile them like this:
perl reproject.pl NX88_001_r.tiff NX88_002_r.tiff......
You could in theory also do:
perl reproject.pl *_r.tiff
but note that this will combine all your rectified tiles into one big image, and if you have lots then it'll boggle your computer.
Hey presto, you have a bunch of tiles in the right directory. Good eh?
If you got a tiff file open error instead then make sure that libtiff is installed. Reinstall Imager afterwards.
Useful stuff to know
It produces tiles at zoom 15 & 16. The original 300dpi scans sit somewhere between these two zoom scales. For lower zoom tiles TomH has a script he can run on the OSM server to produce them.
The code doesn't do any additional processing over and above rectify/crop/reproject/tile (in that order). You could, in theory, add an extra line of code to sharpen the image, or whatever - the Imager library is very good at all this.
Any tiles with more than 7500 black pixels won't be written. Increase this value a bit if you find you are missing tiles at highest zoom. It probably means that tile naturally has a lot of black type or features.
Each 10km square map sheet has a total final size of around 65MB before tiling. Thus a 3 x 3 set of sheets tiled at the same time results in a combined image size of around 590MB. Imager is used to do the final tiling. In doing so the combined tiff image is loaded into memory. This currently eats too much ram for a 3 x 3 area and the process bombs out. Richard will rewrite differently when he gets a chance. A 2 x 2 works ok as does generally a 3 x 2.
Uploading to OSM
Tiles (z15 & z16) are being uploaded to the dev server home/ooc/os1 directory. They are then available for use in potlatch or JOSM. A server script is run periodically to produce z6 to z14 and z17 tiles.
Index
Index of maps held as at 27 August 2011 available as a tabulated list, or as a coloured chart
If you wish to purchase & donate a map that is not in the list then please check with blackadder first as new maps come in all the time and the index may not be fully up to date. All donations would be very much welcomed though (maps or funds to purchase them)
Use
The maps are available via WMS for use in JOSM and as Google format tiles for use in Potlatch, JOSM or Merkaator.
To browse what's been uploaded to date go to http://ooc.openstreetmap.org. Click the layer button on the right hand side and select "OS 1st Edition (1:25,000)"
Editors
JOSM
With JOSM version 3751 or later:
- 'Edit' menu -> 'Preferences...'
- Click 'WMS/TMS' tab on the left
- Click the 'Add' button
- Enter 'OOC OS 1:25k' as the menu name
- Delete any text in the 'Service URL' box.
- Enter in the WMS URL box (the bottom box) the following text string: tms:http://ooc.openstreetmap.org/os1/{zoom}/{x}/{y}.jpg
- 'OK'
- Back in the 'Imagery Preferences' window add the maximum zoom value of 17 in the 'Zoom' column alongside the new line item you just added.
- 'OK'
- Give it a try! Just add the new image layer by selecting it from the 'Imagery' menu.
Please note that you may see error tiles appear if you happen to be at zoom levels 15 or 16 in an area where there is currently no imagery. This will be normal behaviour until we have map tiles for the whole of the available area.
Potlatch
In Potlatch simply select the required background from the Out of copyright list. When editing in Potlatch, press "b" to add the appropriate 1:25k source tag to your objects.
Merkaartor
In Merkaartor add os1 to the TMS adapter (Tools->Preferences->Background Image) with the following:
- Name: OS 1:25k
- Server address: ooc.openstreetmap.org
- Path:/os1/%1/%2/%3.jpg
- Tile size:256
- Minimum zoom:6
- Maximum zoom:17
Source tag
Potlatch uses source=OS 1:25k. It would be good for all users to try and follow this for consistency.
