Georgia Passes Hat to GIS Users

Turned away by the state legislature, Georgia is asking public and private organizations in the state to help fund a project to convert high-resolution aerial photographs into all-purpose geographic images.

The photographs, acquired in partnership with the U.S. Geological Survey and covering the entire state, will provide a much-needed update to the Digital Orthophoto Quarter Quadrangles in the state's Geographic Information System (GIS) Data Clearinghouse.

Digital orthophotos combine aerial photographs with basic mapping data, making it easier to visualize and verify abstract GIS data. State and local agencies, the forest industry and other organizations use those images for a wide range of applications, including development and transportation planning and environmental studies.

But each photograph, covering 3.75-minutes latitude by 3.75-minutes longitude, costs about $375 to scan in and prepare, putting the price tag for the statewide program at $1.5 million. So the clearinghouse is asking those users to help bear the costs, in a program called Adopt-a-Quad.

"Almost every major entity out there has statewide imagery, and they use it extensively," said Tom Mettille, clearinghouse manager. More than "just a pretty picture," the digital orthophoto "is the most important data layer we can build for use in mapping and GIS," he said.

Existing digital images, which date back to 1993, have not aged well, as many parts of the states have grown considerably in the intervening years, Mettille said. Often, roads or housing developments have sprung up where only fields were before. The state is anxious to scan in the images and begin updating the data.

Various state agencies have contributed a total of about $500,000 to start the project, but little additional money is forthcoming. The state GIS Coordinating Committee had requested money from the general assembly but received none. One local government has expressed interest, as has the forest industry, but nothing has materialized yet. Georgia Power is one of the few GIS users to come up with funds, Mettille said.

At present, the state has enough money to begin digitizing images of metropolitan areas, but "most agencies will like to see statewide [imagery]," he said.