High Resolution Historical OS Maps now in OSM

[Updated] – Steve Chilton (designer-in-chief of the “standard” OpenStreetMap map) has announced the first Ordnance Survey 7th Series 1:50000 map scans are now available for tracing on to OpenStreetMap. The first ones available are in the south-west of Scotland. Further details of the project area are here.

On the right is what Girvan, a town in Ayrshire and Galloway, looks like in OpenStreetMap currently. Below that is what the 7th series imagery offers – and, bottom, the modern-day Google mapping data. This shows that, for even some sizeable towns, a 50-year-old map still has a lot to offer to enrich OpenStreetMap.

The scans have been reprojected into the “Spherical Mercator” format so they can be used in Potlatch – OpenStreetMap’s main online editor. They build on the New Popular Edition maps, which have been reprojected in England and Wales, but not Scotland so far, allowing OSM contributors to add features from the maps into the project.

Because the maps are (just) over 50 years old, their Crown Copyright has expired, which is why they can now be included in the project. Unfortunately many of the 7th series maps were printed in the early 1960s, so we’ll have to wait a few more years for these to come out of copyright and Scotland be fully covered. It would be lovely of course if the OS were to waive the copyright on these…

The maps can be seen directly here – the quality of the imagery is excellent, as can be seen in the screenshot above. Incidentally, the tilt of the grid squares is very noticeable here – the angle between grid and “true” north is quite pronounced in west Scotland.

[Update – The NPE, OS 7th Edition mentioned here, and a small number of 1:25000 OS 1st Edition maps can be directly compared on the new OOC map.]