High-tech maps measure trends, not turnpikes Computer maps are based on images from satellites.

April 20, 1992|By Glenn Small | Glenn Small,Staff Writer

Towson State University, the Maryland Office of Planning and a Towson consultant are teaming up to create a series of computer land-use maps, based on the colorful images from a space satellite.

The computer maps, which will detail geographic features such as forests, streams, wetlands and all the various forms of development, could be important in monitoring growth trends in the state and their impact on the environment, those involved in the project said.

Unlike computer maps used mainly to help people navigate over the state's roadways, these land-use, land-cover maps will show what development has taken place in Maryland over time.

"Traditionally, we used maps to navigate from point A to point B. Today, we're using maps to tell us how to use space," said Dr. John M. Morgan III, a geography professor at Towson State.

Sitting at a computer terminal on campus, Dr. Morgan can punch a few keys and a satellite image of the Towson area appears. At first, it looks like a rainbow of colors.

But after Dr. Morgan hits a few more keys, the outlines of Interstate 695 and other major roads appear, and the colors on the screen take shape, from the intensely developed splotch that is downtown Towson, to the dark green of the woodland surrounding Loch Raven Reservoir.

By this fall, Dr. Morgan, a graduate assistant and geography undergraduate students hope to have nine of the state's 23 counties on computer maps. They hope to have the entire state mapped by next spring.

They are working under a $125,000 contract from the Maryland Office of Planning to develop the land-use, land-cover maps, which are used by local and state agencies to monitor changes in residential and commercial development, forests, wetlands and agricultural land.

The idea of creating maps that show what uses are being made of land in Maryland is not new. The first such set of maps was made from aerial photographs in 1973, according to John M. Garber, manager of systems support in the Maryland Office of Planning.

But because of the high cost of aerial photographs -- $30,000 to $50,000 for photos of the entire state -- the land-use maps have been done irregularly, Mr. Garber said.

For instance, it was not until 1981 -- eight years after the first maps -- that the second maps were done. Others were done in 1985 and 1990, he said.

And usually, by the time the maps are finished, the data is several years old.

With satellite data, which costs about $21,500, the land-use maps can be updated every year, Mr. Garber said.

Under the Towson State contract, the university will take 1988 satellite images of Maryland and 1991 satellite images and develop two sets of maps to show the changes in land use that occurred during those three years.

A Towson firm, Data Chromatics Inc., is being paid $143,000 to help Towson State get started.

That company will help train Dr. Morgan and students in interpreting and coding the satellite data, said Ken Kinsey, president of Data Chromatics.

The satellite information comes from the Earth Observation Satellite Co., or EOSAT. The images it sends back are basically a measure of reflected light and heat, as seen from space, Mr. Kinsey said.

Because each geographic feature, such as a lake, a patch of woods or a parking lot, gives off a unique reflection of heat and light, the satellite images are useful in accurately distinguishing features on the ground.

An empty parking lot, for example, and one full of cars, would each reflect light in their own unique ways, Mr. Kinsey said.

"It's like a fingerprint," he said.

According to Dr. Morgan, Towson State hopes to become the expert and statewide clearinghouse for computer land-use maps, based on satellite imagery. Later this year, they plan to offer for sale a satellite print map of Maryland.

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