About this project

Online geographic tools allow historic maps to be overlaid on modern mapping, enhancing the ability to view and compare the past with the present, and improving findability. Georeferencing, i.e. assigning points on a map image to corresponding geographical co-ordinates, links the map to its spatial location on the ground using universal geographic standards (latitude / longitude).

Background

The British Library began a project to crowdsource the georeferencing of its scanned historic mapping by partnering with Klokan Technologies to customise its online georeferencing tool. The initial pilot, released in February 2012, was a tremendous success, with all 724 maps georeferenced by the public in less than one week. It is hoped that this second group of maps released to the public for georeferencing, of a similar size, will be equally popular.

The maps

For this second phase of BL Georeferencer, we have included a wide variety of maps dating from as early as the 16th century, up to the 20th century. The focus remains on areas that fall within the present United Kingdom, but the range is much broader, reflecting more dates, mapmakers, purposes and scales.

Whereas the initial round of BL Georeferencer was limited to two well-known collections, The Ordnance Surveyors' Drawings and the Crace Collection of maps of London, and this contains some of those materials, the second phase also draws from King George III’s Topographical Collection and from maps contained within 16th and 17th century manuscripts. It also includes maps of a modern vintage, with the outstanding British map publishers of the 19th and 20th centuries represented, as well as the "modern" themes of car, rail and air transport, medical and social mapping, and maps related to the world wars. This presents a better-rounded, if less orderly, representation of UK mapping.

Results

Through georeferencing, the selected maps were spatially enabled, making them geographically searchable and able to be visualised using geospatial tools and combined with other maps online. In less than two weeks after the initial work was completed, the maps were added to the portal Old Maps Online, which uses a geographic search interface to identify and view historic maps from numerous collections online. Future georeferenced maps will also be made available in Old Maps Online.

The output of this work may also be viewed using the BL Georeferencer interactive map and directly from the Online Gallery map pages. Users are encouraged to add points to maps to improve the georeferencing, and to use the "Clip" tool to mark the borders of the map so that margins may be removed to improve viewing and allow seaming of contiguous maps.

The Library is grateful to all the participants who generously contributed their time, in particular to a small group of "expert" users whose work was substantial.

Further information

Queries should be directed to georeferencer@bl.uk. To connect with other users of this technology and participate in discussions, join the User Group of our technology supplier, Klokan Technologies.

For more information on the initial implementation of the British Library Georeferencer, see Kimberly C. Kowal and Petr Pridal. "Online georeferencing for libraries: the British Library implementation of Georeferencer for spatial metadata enhancement and public engagement" Journal of Map & Geography Libraries: Advances in Geospatial Information, Collections & Archives, 8:3, 276-289. To request access to this article online, contact georeferencer@bl.uk.