New Direction in Mapmaking; Computers Cut Process of Cartography to Minutes

The Washington Times (Washington, DC), September 21, 2006 | Go to article overview

New Direction in Mapmaking; Computers Cut Process of Cartography to Minutes


Byline: Shelley Widhalm, THE WASHINGTON TIMES

Until about 30 years ago, cartographers took hours, days or months to hand-draw maps. The mapmakers worked at drafting tables with pen and ink, T-squares and specialized tools for lettering and drawing shapes, or they used scribing techniques to cut or engrave line work into a special material used to make negatives.

Today, mapmakers sit in front of computers and use map-making software to produce automated and digitized maps.

"Computer mapping has changed the whole world of cartography," says Tanya Allison, professor and program coordinator of applied geography at Montgomery College in Rockville. "It could take days to months to complete a map. Now, we can create a map within minutes."

Ancient mapmakers used a global map coordinate system of longitude, latitude and elevation to make early maps of the Earth, says Richard Pearsall, a 30-year cartographer with the U.S. Geological Survey in Reston. The Greeks developed the concept of latitude and longitude in 150 B.C., he says.

"By the fact that the Earth rotates on its axis and revolves around the sun, the sun and stars appear to move across the sky on a known track," Mr. Pearsall says. "Through observations of the sun and stars, mariners and explorers used precise equipment called a sextant and a precise timepiece called a chronometer that was synchronized with a master clock in Greenwich, England, to accurately measure their latitude and longitude on the Earth."

In 1884, more than 25 nations adopted a standard for latitude and longitude and selected Greenwich as the location for the zero longitude line, Mr. Pearsall says.

"Even though equipment and techniques have evolved over time, the basic premise of mapping has not changed since the days of the ancient mariner," Mr. Pearsall says.

Mapping requires converting the three-dimensional form of Earth's curved surface to two dimensions. A process called data projection uses mathematical calculations to make the conversion and flatten Earth's surface onto paper. Cartographers have developed hundreds of projections or grid systems to represent Earth and its continents in circular, square, conic and other shapes.

Cartographers use these grid systems as the foundation to begin building maps, such as reference maps, political maps that indicate boundaries, physical maps that show some of the features of the Earth's surface, and thematic maps that provide data to analyze phenomena such as economic changes and population growth.

The cartographer making a map has to determine the area to be mapped, the message to be imparted and the sources that can provide the information, says John Hebert, chief of the Geography and Map Division of the Library of Congress.

"That information has to be made into geographic reality," Mr. Hebert says. "There has to be an agreement of what the intention of the map is, and that varies with each map."

Initially, cartographers had to rely on ground-survey data to generate data for maps. However, as technology progressed from hot-air balloons to airplanes to satellites and, most recently, to Global Positioning Systems (GPS), cartography could incorporate the use of aerial photography, satellite images and remote sensing for additional data sources, Mr. …

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