County to Collect Field Data for GIS


Fairfax County Office of Public Affairs
12000 Government Center Parkway, Suite 551
Fairfax, VA 22035-0065
703-324-3187, TTY 703-324-2935, FAX 703-324-2010

Feb. 19, 2004

 

County to Collect Field Data for GIS

Over the next few months, two separate field projects are being initiated that will support Fairfax County’s Geographic Information System. Through spring, field crews will be placing Global Positioning System surveying equipment and location markers around the county and gathering photos and elevation data that will be used to update GIS.

Color Aerial Photography Spring 2004 Mission

The first project will involve updating the color aerial photography for the southeast quadrant of the county. This imagery is widely used in the county’s GIS by most county agencies, in particular the Police and Fire and Rescue departments, the Department of Public Works and Environmental Services and the Department of Planning and Zoning. This imagery also is used by residents and businesses, including developers and realtors.

The photography is taken from specially equipped aircraft that fly at about 4,000 feet above ground. Markers (panels) that will be visible in the photographs must be placed at specific locations on the ground in order to link the photography to the county GIS. The markers are either white plastic sheeting on soil, or paint on pavement. The markers are in the shape of a “Y� with each arm about 5'x1' and are generally placed on public land.

Survey crews will have to place these rather large markers on the ground at precise locations and maintain them for three to six weeks until the aerial photography is completed. County survey crews will have identification and a letter from the county describing the project. Because the markers must be left on the ground until all of the photography is taken, the county requests residents’ cooperation and help in keeping the markers protected until completion of the photography-flying mission.

Height Modernization Project

The second project takes place across the county and involves updating the elevation data for the county. This will enable the county to maintain its older elevation data and also create modern elevation data compatible with national and state mapping standards.

The newer elevation data will be compatible with other more versatile and efficient sensor technologies and systems, such as GPS. Because the county is currently working with the Federal Emergency Management Agency to enhance floodplain data, this will make the county consistent with FEMA standards. It will also provide cost savings to the county when updating aerial photography and to surveyors who use GPS in their field work.

The process of improving the elevation data for the county involves placing high accuracy GPS receivers at over 100 precise locations around the county. The equipment must remain in place for several hours. Duplicate sets of measurements must be made on subsequent days. As a result, surveyors will be visiting areas throughout the county until June to place and monitor the equipment over several days. Both county survey and contractor staff will be doing this field work. They will have identification and a letter from the county describing the project.

For more information about these GIS projects, contact Yogendra Singh, GIS project manager, at 703-324-3882, TTY 711.

FAIRFAX COUNTY IS COMMITTED TO A POLICY OF NONDISCRIMINATION IN ALL COUNTY PROGRAMS, SERVICES AND ACTIVITIES AND WILL PROVIDE REASONABLE ACCOMMODATIONS UPON REQUEST. TO REQUEST SPECIAL ACCOMMODATIONS, CALL 703-324-3187, TTY 703-324-2935. PLEASE ALLOW FIVE WORKING DAYS IN ADVANCE OF EVENTS IN ORDER TO MAKE THE NECESSARY ARRANGEMENTS.

 


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