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Map warping at the New York Public Library

Emily Spivack ( Bio / Posts ) | Thursday, February 10, 2011 UTC

The NYPL Map Rectifier is a tool for digitally aligning (“rectifying”) historical maps from the NYPL’s collections to match today’s precise maps. Visitors can browse already rectified maps or assist the NYPL by aligning a map. Play the video to tour the site and learn how to rectify a map yourself.

At Tuesday’s Social Media Week event, Future Library: Socializing History with Maps, the New York Public Library’s Geospatial Librarian, Matt Knutzen, explained how the Library has undertaken a project to align its collection of 10,000+ digitized historical maps of New York City to current, more accurate maps. What’s particularly exciting is that the project is open to the public; anyone can help match old with new. With its Map Rectifier, “we can turn historical maps into spatial data,” Knutzen explained. Users plot a few points on an older map that correspond with the latitude and longitude of a current day map. Using geo-rectification, a.k.a. map warping, old NYC streets, buildings, transportation, and landmarks come into focus within a contemporary framework.

This New York Public Library video provides a detailed tutorial on how to rectify a map’s data.