World Wide Web Expedites Access to USGS Mapping Data

Except for printed topographic maps, USGS geospatial (mapping) data have not been readily accessible to the general public in the past. Because of their size and complexity, these data traditionally were stored on and distributed on bulky tapes from hard-to-use mainframe computer systems. Customers were mainly limited to government and commercial organizations able to afford and operate the expensive geographic information system software needed to create maps from the data. All of that has changed.

The growing availability of powerful desktop computers, simple browsing software, and inexpensive links to the Internet World Wide Web has provided the perfect vehicle for USGS to share easily and at the lowest cost possible its vast collections of digital mapping data, aerial photography, and satellite-derived imagery.

The primary USGS Web gateway to these invaluable national assets is the National Mapping Information Server (http://mapping.usgs.gov/). Customers wishing to locate and

Aerial photographs like this one of Boston Harbor (Logan Airport) are accessible through USGS websites.

GLIS entry screen is useful for finding scientific products (http://edcwww.cr.usgs.gov/webglis/).

To obtain specific products, customers are directed to the Global Land Information System (GLIS) (http://edcwww.cr.usgs.gov/webglis/). Using GLIS, customers can graphically query inventory holdings to determine data availability, view extensive online metadata and data set documentation to determine suitability, examine online digital browse images, and place online requests for products.

obtain specific products can follow links from the Mapping Information homepage to a variety of general and technical information resources, including product descriptions, graphics depicting availability, examples, price, and ordering instructions. Professional customers are encouraged to enter the USGS National Mapping and Remotely Sensed Data Clearinghouse (http://mapping.usgs.gov/nsdi/) node of the Federal National Spatial Data Infrastructure (http://nsdi.usgs.gov/nsdi/), which provides technical product descriptions and collection-level metadata (data about data), as well as links to other Federal, State, and local geospatial data resources. In addition to the highly technical information available, the general public can obtain product information of a less technical nature through links to online fact sheets.

Many types of digital mapping data, especially digital images from aerial or satellite photographs, are too large to deliver over the Internet efficiently, and are usually distributed on CD-ROM or tape. Selected digital data sets are available for downloading at no cost from the U.S. GeoData online repository (http://
edcwww.cr.usgs.gov/doc/edchome/ndcdb/ndcdb.html).

TerraServer: Seeing Your Neighborhood from the Sky

Ever wonder what an aerial view of your neighborhood might look like?

Now, with a few mouse clicks scientists, planners, consumers, and school children can see USGS aerial images with resolutions as close as 3 feet -- enough to distinguish buildings and cars, but not people -- over the Internet using the new Microsoft TerraServer (http://www.terraserver.microsoft.com).

In 1997 USGS and the Microsoft Corporation entered into a cooperative research and development agreement to make vast amounts of geospatial data available to the general public through the Internet. Under the 36-month joint effort, Microsoft agreed to modify a massive volume of USGS geospatial data so that images can be quickly and easily displayed with unprecedented clarity over the Internet.

The Microsoft TerraServer website opened to the public in June 1998 serving more than one terabyte (1,000,000,000,000 bytes) of geospatial data from a user-friendly interface. The TerraServer enables users to view and download digital orthophoto quadrangle images -- digital images of aerial photography that combine the image characteristics of a photograph with the geometric qualities of a map.

Initial response to the TerraServer has been spectacular. Early statistics show the average number of hits at 12 million per day with a peak of almost 29 million hits on July 1.