Historical Map Mashups Turn Cities Into Glass Onions of Time
The image above looks like a bit of a mess, but that’s only because it’s two maps of lower Manhattan layered on top of one another — an 1891 street map overlaid by a 2006 map of the NYC Subway system.
The screenshot is taken from Hypercities, a MacArthur-funded project to help create these kinds of historical analysis tools. Currently, the site has 39 maps of New York City made between 1766 and 2009, all of which have been aligned using open-source software tools so their transparencies can be adjusted. You can juxtapose any number of maps you’d like — ranging from a map of government buildings made around the time of Washington’s inauguration to 1990s demographic maps marking ethnicity and income — effectively letting you peel New York City like a giant onion, exposing layers of history as you go.
Old maps are dug up and scanned, then specific points are plotted against known lat-long data from OpenStreetMap and other open geodatabases. The older maps are then “rubber sheeted,” or stretched to be match modern geo-data. Lastly, the maps are tiled and fed into a database that make this sort of front-end mashup possible.
Hypercities also has time-layered views of Los Angeles, Berlin, Tel Aviv, Cairo, a historical site in Peru and a few other world cities.
Hypercities is just one such project. Cartifact is also doing something similar. Both were part of a presentation Thursday at the Where 2.0 Conference by Michal Migurski of Stamen Design, the small firm responsible for Digg’s data visualizations and the infamous Oakland Crimespotting map mashup.
Also be sure to check out Migurski’s own project called Old Oakland. He overlaid historical maps of Oakland using a scanner, Photoshop, and getlatlon.com, a site created by Simon Willison that gives you latitude and longitude coordinates for any point on a map anywhere in the world.
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