Historic maps in the public domain
Maps contained within the pages of 17th-, 18th-, and 19th-century books are still being unearthed. Of the one million images that the Library extracted from scanned volumes and explosed on Flickr Commons, over 2,100 have already been tagged as maps by the public!
As these map images are in the public domain and so open for reuse, we've seen new interpretations, further exposure, and interesting geospatial applications. For instance, John Leighton's 1895 diagrammatic map of London Indexed in Two-Mile Hexagons has been brought up to date and into space in this dynamic visualisation created for International Open Data Day tomorrow in Osaka City, Japan. Though I've been warned that this is a work-in-progress, it is impressive already; the newly geo-aware index is interactively linked to its 18 component hexagonal maps, with the current location in OpenStreetMap appearing alongside. Ollie described the purpose of Leighton's mapping scheme in his Mapping London blog post in December. The results of making these maps available just keep getting better.
Work-in-progress at http://museum-media.jp/london/
Leighton's index map, the 18 component maps, and other images from the book
Here at the Library we're anticipating opening up the 2,100+ maps for public georeferencing. Once all of the one million images get tagged with keywords in Flickr, those identified as maps will be consolidated and released via BL Georeferencer. Please lend a hand by finding and tagging any maps among the remaining images!