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The Historic Map Layers

Posted by Duncan Hay on Sept. 20, 2016

One of the quirks of copyright is that even if an old map is well out of its copyright term, reproductions of that map automatically become the copyright of whoever made the copy. So that whilst it’s possible for academics to download and view old maps from the University of Edinburgh’s Digimap collections (https://digimap.edina.ac.uk/) for research purposes, it’s not possible to put them online for others to view. We have two historic map layers available on Histories of Whitechapel: the Rocque map of 1746 and the 1873 Ordnance Survey, donated by the Institute of Historical Research (http://www.history.ac.uk/) and Tower Hamlets Local History Library and Archives (https://www.ideastore.co.uk/local-history) respectively.

The Rocque Map scan was produced for the Locating London’s Past project (https://www.locatinglondon.org/), and the process by which it was created was quite involved due to the age of the map sheets and the way they were made. You can read about the process on their blog https://locatinglondonspast.wordpress.com/2011/06/22/recreating-rocque-london-1746/. We’ve published just a small excerpt on the Histories of Whitechapel map. There are some lovely details: taking a look at the area around East London Mosque, it seems quite likely that Fieldgate Street is so called because it was the street that led to the fields:

14 Whitechapel Road, Currently Haji Nanna Biryani, which the Survey have identified as formerly being the George public house, constructed c.1881, is on the site of an even older building, the George Inn. This suggests that food and drink have been served on this site for at least 270 years:

The 1873 Ordnance Survey map was provided by Tower Hamlets Local History Library and Archives, who are in possession of a complete set of this edition for the borough. Unlike the Rocque, we had to scan and georeference this ourselves. The map sheets (each around 1000x800mm) were scanned using a sheet-feed map scanner by Nick Mann at UCL, and then retouched in Photoshop. From here they were imported into QGIS (http://www.qgis.org/en/site/) and georeferenced, which involves matching up points on the scan with the contemporary street network. We used our building footprints (see https://surveyoflondon.org/blog/2016/how-we-made-map/) as our reference.

For some areas this was easier than in others: along Whitechapel Road, many of the original shop frontages are still in place, and pubs (easily identified by the 'P.H.' on the OS map), even if no longer being used for their original purpose, are in many cases still there. However, other areas (for example around Aldgate), have seen huge changes since the 1880s, and it’s trickier to align the old map with the new.

One of the nicest things about our 1873 OS layer is that the particular copies Tower Hamlets Local History Library and Archives lent us have obviously been heavily used. Some of the sheets are in quite poor condition: the south-western area of the study area (around the Royal Mint Estate, towards the Tower of London) in particular is quite tatty, and in places you can see where it’s been torn and taped to hold it together:

In other places it’s been annotated, for example on this area by Wellclose Square:

The buildings these marks refer to are gone, and we don’t know what the annotations mean, but it’s a nice illustration of the way that the historic maps aren’t just useful in that we can use them to see what’s changed between then and now, but are tangible documents whose condition testifies to their history of ownership and use.

How we made the Map

Posted by Duncan Hay on Sept. 1, 2016

When the project was conceived, the Survey of London had hoped to use Ordnance Survey MasterMap as the source of our building outlines, as this is the basis of all of the maps in the Survey of London volumes. However, the terms of the OS licence prevents you from using MasterMap data online in this way, so we had to look at other options.

Our first option was to use OpenStreetMap, but these weren’t detailed enough for our purposes, and there were mismatch issues when working with historic maps because of the different map projections used by OpenStreetMap and by British cartographers. We therefore looked at two Open Government Licensed maps as the source for our buildings: the Ordnance Survey OpenMap Local, which contains block-level building outlines, and the Land Registry’s vector map of the UK’s land ownership units.

Because Whitechapel is a relatively small area we decided to manually split the OpenMap Local building footprints using the Land Registry polygons as a guide. However, Adam Dennett at CASA developed a method for programmatically splitting the OpenMap local polygons, meaning that this method for producing building footprint polygons could potentially be scalable to the whole of the UK. However, we soon ran into another problem: despite the Land Registry polygons being published under an Open Government Licence, because they are ultimately derived from MasterMap, we were advised that building footprints created in this way couldn’t be published online either, which left us back at square one.

Our final option was to draw our buildings from scratch. Happily, there was another open data set which we could use as a basis: the LIDAR imagery released by the Environment Agency. LIDAR is a scanning technique which involves firing a laser from an aircraft at the ground and measuring the time that it takes for the light to bounce back. The results can be used to build up detailed pictures of landscapes and the built environment, which look like this:

LIDAR imagery, © Environment Agency copyright / and or database right 2015

This image shows a section of Whitechapel Road. Whitechapel Station is the large pale orange rectangle towards the top, with the tube line (at this point open to the air) visible as the dark red swathe across the whole image. The light blue shapes are the shopfronts on Whitechapel Road, the dark blue shape at the bottom the former Royal London Hospital building. You can just about make out some of the market stalls, and trees tend to show up as clusters of blue dots.

Whilst for larger buildings it was fairly easy to trace the outlines, it got quite complex around the backs of older buildings, particularly on Whitechapel Road. Moreover, Whitechapel is changing very rapidly, and the LIDAR imagery itself in many places doesn’t reflect what’s on the ground at the moment. However, it was good enough for our purposes to make a first pass. We then spent several days walking around Whitechapel with print-outs verifying what we’d done, and the interactive building outlines on the map are the result.