Summary

Description

Digital orthographic imagery datasets contain georeferenced images of the Earth's surface, collected by a sensor in which object displacement has been removed for sensor distortions and orientation, and terrain relief. Digital orthoimages have the geometric characteristics of a map, and image qualities of a photograph. (Source: Circular A-16, p. 16) These files contain Digital Orthophoto files for the State of Virginia developed from imagery acquired in spring 2006 and 2007. In the spring of 2006, the Commonwealth of Virginia, through the VGIN of the VITA contracted with the Sanborn Map Company to provide aerial data acquisition, ground control, aerotriangulation and development of statewide DTM and digital orthophotography. Approximately 15% of the State was acquired in the year 2006 and the balance in 2007. All data acquired in 2006 is jurisdiction based. The data acquired in 2007 includes overlap along the boundaries of jurisdictions captured in the previous year 2006. This ensures each jurisdiction has full coverage from either Year 2006 or 2007 without 'mixing' imagery vintage along the edge of a jurisdiction. The project encompasses the entire land area of the Commonwealth of Virginia. The State boundary is buffered by 1000'. Coastal areas of the State bordering the Atlantic Ocean or the Chesapeake Bay are buffered by 1000' or the extent of man-made features extending from shore. The entire State was intially designed to support 1"=200' (1:2400) scale mapping. Jurisdictions throughout the State were provided an option to upgrade to a 1"=100' (1:1200) map scale. All data development processes for the DTM conform to the ASPRS Draft Aerial Photography Standards (1995) and Model Virginia Map Accuracy Standards (1992), which generally follow the ASPRS Accuracy Standard for Large-Scale Mapping (1990) for relevant mapping scales. The DTM supports the creation of 6-inch or 1-foot map orthoimagery at the relevant scales.