Digital NYC: GIS Demo

In the fall of 2005 Columbia University Libraries investigated the possibility using a GIS interface as a finding aid for Digital NYC, a collection of images and other content relating to the history of New York City. This research tool would allow users to browse the collection geographically by hyperlinking both images and text-based content to points of interest on historical maps of New York.   

A. Project Overview

In an attempt to provide an innovative method of browsing historical content related to New York City in the 19th Century, a GIS interface was created which allows users to locate, sort and link to information relevant to landmarks of interest visually as an alternative to traditional text-base search methods.

Using a geocorrected portion of Matthew Dripps' Map of the City of New York Extending Northward to Fiftieth Street (1851) landmarks of historical significance were located and geographically encoded into shapefiles which serve as the distinct layers of the GIS environment. Also embedded in the xml metadata of a subset of the layers are links to images of the landmarks as they appeared in the 19th century. In addition, there is the ability to link directly to Google searches for further information of locations of interest.

B.  Technologies Used

Geocoding: ESRI ArcMap software was used for the geocorrection of the Dripps map and encoding of data points.

Interface: Timemap open source software was used to generate the prototype's interface. The software uses a java applet that does not need to be downloaded and weighs only 350k.

Map Display: Due to the large (>350mb) file size of the geocorrected image of the Dripps map, Zoomify software was used to break up the image into thousands of more manageable pieces. The result is similar to MrSID, but Zoomify free to use.

C. Encoding Process

1. Dripps Map was converted to jpeg format and cropped to reduce file size.
2. Map was geocorrected to correspond with a modern street map of New York City to insure compatibility between the two.
3. Locations of historical significance were identified and encoded as spatial data.
4. .dbf files were then created which provide the metadata for the geoencoded points.
5. The two were then merged and exported as shapefiles which can be interpreted and displayed by the Timemap software.
6. The shapefiles were imported into Timemap added to a predefined spatial extent as map layers.
7. Metadata for the layers was then edited to allow for external hyperlinking.
8. The results were published in a web friendly format and uploaded to a Columbia server.

NB: Because Columbia's Digital NYC image collection is still in its preliminary phases, points on the map are linked to images found in NYPL's Mid Manhattan Picture Collection and are the property of NYPL.

D.  Layering

GIS technology allows encoded spatial references to be filtered by subject or functionality through the addition of multiple, distinct layers of data to a single base map. Layers included in the prototype are:

• Banks
• Businesses
• Fire Companies
• Hospitals
• Hotels
• Law Enforcement
• Libraries and museums
• Markets
• Military Buildings
• Mills and Factories
• Miscellaneous Landmarks
• Parks and Squares
• Prisons
• Public Buildings
• Publishers
• Railroad Stations
• Religious Landmarks
• Private Residences
• Colleges and Schools
• Theaters and Halls
• Storage Yards
• Image Linked Landmarks
• All Landmarks
  
  

E.  Potential Project Functionality

• Ability to link to keyword search results in CLIO
• Explanation of map coverage to include all of Manhattan Island and possibly beyond.
• Links to brief landmark descriptions such as those found in the Stokes Iconography of Manhattan.
• Links to additional text-based content such as Columbia Theses relating to New York.
• Addition of layers locating the homes and businesses of famous New Yorkers.
• Links to other New York related Columbia initiatives such the Herbert H. Lehman Project and Notable New Yorkers oral history collection.
• Greatly increased data retrieval speeds with the use of server side technologies, especially at startup.
• Improved interface design, facilitating greater understanding of GIS functionality.

F.  A Note About Historical Accuracy

Because the goal of this prototype is to convey the potential value of a GIS-based research tool, it may contain historical inaccuracies and should not, at least in this stage of its development, be seen as an authoritative resource.

Credits: The original prototype for this project was developed by Scott Beebe (2005 LDPD Intern).  GIS consulting was provided by Jeremiah Trinidad of Columbia's EDS lab.  The digital image of the 1852 Dripps map of New York which served as the backbone of the project was generously donated by David Rumsey.