Maintenance of the Base Map
In order to maintain an accurate Loudoun County base map, which serves as the foundation for all of the Loudoun County digital data layers, aerial photographs of the county are acquired each spring. Since 1979, with the exception of 1983, 1984, and 1985, Loudoun County has obtained 1 inch equals 1,000 foot scale aerial photographs.
These photographs are used to update the base map with areas of new construction, new roads, buildings, and other features. Topography data is updated as required. The photographs are taken each spring, before leaves and open buds are on deciduous trees and shrubbery and after all the snow and frost has melted. Loudoun County was historically flown in a north / south direction, creating 9 inch by 9 inch, overlapping, black and white stereo photographs that were suitable for 1:2,400-scale maps with a contour interval of 5 feet.
Where to View the Photos
In the years 1978, 1986, 1988, 1989, and 1990, color photos were acquired matching the requirements of the black and white photographs. These photographs are available for viewing at the Loudoun County Office of Mapping and Geographic Information's public information counter.
The county also has digital imagery. There are scanned, countywide, black and white images for 1937 and 1957. Beginning in 2002, the county has been flown with a color digital camera, and digital images are available for every year since. The latest image is always used in WebLogis
, the Online Mapping System.