18 April 2014
The New York Public Library “has now scanned nearly all of its public domain New York City atlases (a collection of now more than 10,000 maps) … and built a web tool … where users both inside and outside the Library can virtually stretch old maps onto a digital model of the world à la Google Maps or OpenStreetMap, thus creating a new copy that is not only aligned with spatial coordinates on the Earth, but normalized across the entire archive of old maps. …
“When we make a digital image of a map, there is nothing inherently geographic about it. It, like a photograph of a person or building, is a mass of pixels of varying color. A computer cannot presently look at pixels on a map and divine its geographic locale. This is where map warping comes into the picture. Using the tool we’ve created at maps.nypl.org, we enable users to geolocate pixels on a map. …
“Once we’ve done that, we can walk this digital spatial object through a workflow, adding useful information and context with each step. All of this is done collaboratively, through the piecemeal efforts of staff, volunteers, and interns, a group of roughly 1,500 participants worldwide.” --- Matt Knutzen, Map Division, NYPL
For a much more detailed explanation of the project, and a gateway to the maps, click http://www.nypl.org/blog/2012/01/10/unbinding-atlas-working-digital-maps