Traditional maps provide a way to visualize a wide range of static data. Here a group of cartographers, geographers, environmentalists and demographers have created a dynamic map that uses computer animation to show urban growth over time--in this case 200 years of development in the Baltimore-Washington region.

The goal of the project is to provide urban planners with a visual means of studying the growth of metropolitan areas--and to allow them to project the impact of future development. The animation you see here consists of just four frames taken from a far more extensive computer simulation.

The animation was prepared by the Baltimore-Washington Regional Collaboratory, a cooperative effort between several universities and agencies, including the University of Maryland Baltimore County, the National Aeronautics and Space Administration's Mission to Planet Earth, and the U.S. Geological Survey (USGS). The project was unveiled on April 22 in Baltimore during the annual convention of the American Society for Photogrammetry and Remote Sensing and the American Congress on Surveying and Mapping. In the images shown here, the red areas represent "urbanization"--places in which much of the land is covered by structures.

This real-world "SimCity" is an example of temporal urban mapping. This technique relies on modern mapping techniques, such as remote sensing and geographic information systems, to capture information from both historical and modern records. The database highlights the profound changes to the landscape over time.

The researchers involved in the project have reconstructed urban growth patterns for specific years since 1792 by examining historical maps and census data gathered from the Library of Congress, the U.S. Bureau of the Census, the USGS and the Maryland Historical Society. Data from the Bureau of the Census were used to identify the beginning of villages that might not have yet been represented on historical maps. All of that information was combined with current land satellite images. Workers at the Goddard Space Flight Center also provided real-time satellite data. A computer algorithm then projected likely growth from one key year to the next, based on records concerning the appearance of houses, roads, villages, towns and commercial land areas. The Collaboratory project also tracked coastal water changes in the Chesapeake Bay region.

Planners working with the database can produce map animations that show specific features, such as roads or forests. For example, the Chesapeake Bay Regional Ecosystem Group plans to correlate the decrease of water quality to urban growth. The data can be displayed on various backgrounds, such as shaded relief or digital elevation models.

Perhaps the most important aspect of the Collaboratory project will be its ability to predict future changes. Some planners are already working with the model to find ways to forecast the impact of human activity in the region, such as new roads, shopping malls and mass-transit systems.

"A historical perspective of urban development provides insights into future development and expansion trends," says William Acevedo, a physical scientist with the USGS EROS Ames Research Group in Moffett Field, California. "It is extremely important that we understand the spatial dynamics of urban sprawl so that future patterns of land use and land cover can be projected, planned, and managed under sustainable conditions."

Additional images, descriptions of research projects, underlying data and other information are available from the Baltimore-Washington Regional Collaboratory. There are also quicktime movies of various animations that can be downloaded from the site.