Geo-Spatial Data

Geo-Spatial data can be defined as data that is prepared for use in a GIS software. This type of data can be vector or raster and generally contains spatial features, a table containing attributes about the spatial features, and a spatial reference system that identifies where the spatial feature are located in geographic space. Often geo-spatial data is comprised of several files that make up a metafile. This metafile often represents a common set of spatial features that reflect a similar theme and may be reffered to as a theme, coverage, or layer. An example of this may be a transportation layer that may be a metafile made up of a vector line file representing streets, a table containing the lengths and names of the streets dynamically linked to each vector line, and a spatial reference file that provides the means of measuring distances along or between streets.

ArcView is the most widely available GIS software at Yale. Depending on which vesion of the software is used (3.2 or 8.1), different file names will be encountered. Using ArcView 3.2, a typical metafile is generally made up of three files: the shapefile (.shp), a table (.dbf), and an index of the feature geometry (.shx). However, all three of these files together make up a metafile also called a shapefile. Click here for a table of some common geospatial data formats:

Geo-spatial data is available in a variety of places. The GIS Center in the Map Collection (Sterling Memorial Library) is starting to build a collection of geo-spatial data which is primarily based on requests by patrons (see the Service page for more information on how to make requests for Geo-Spatial data). However, there is a large amount of geo-spatial available on the web or from ftp sites. Visit the Resources page to see what is available. Below is a list of some of the major geo-spatial data sets currently available at the GIS Center on CD ROM or hard drive) in the Map Collection:

• 1990, 2000 SF1 U.S. Census, 2000 SF3 (Geolytics Census CD)
• Africa Data Sampler (World Resources Institute)
• Cambodian Genocide Project (Yale University)
• Census Transportaion Planning Package (CTPP; for whole U.S.)
• Digital Chart of the World (ESRI).
• ESRI Data & Maps 2000 (7 CD's with coverage of the world, detailed of U.S. States, Europe, Canada, Mexico, ArcGIS StreetMap USA)
• GIS of Panama (Eon Systems)
• National Transportation Atlas Databases 2001 (BTS).
• National Elevation Data (Conterminous U.S., Alaska and Hawaii)
• Various LandSat 7 Satellite Photos

There is also geo-spatial data located at other places on campus such as the Statlab, Gov Docs Library, Geology Library, and the Center for Earth Observation. The Yale University Library catalog (Orbis) or Statcat (hosted by the Statlab) can be searched for holdings. Searching for geo-spatial data on Orbis can be a difficult task. There is no way to query the catalog just for geo-spatial data. The best thing to do is to limit your search to CD for format and try a variety of keywords.

There is also a large variety of geospatial data sets available outside of Yale. See the Resources link to view links to these resources.