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A Digital Orthophoto Quadrangle (DOQ) is a computer-generated image of an aerial photograph in which the image displacement caused by terrain relief and camera tilt has been removed. The DOQ combines the image characteristics of the original photograph with the georeferenced qualities of a map.
The DOQQs were provided to IU by the Natural Resources Conservation Service (NRCS), a component of the US Department of Agriculture.
The archive includes DOQQs (each image covers 1/4 of a USGS 1:24,000 quadrangle map) and DOQ mosaics (multtiple DOQQs combined to cover the extent of a USGS 1:100,000 quadrangle map). DOQQ MrSIDs were compressed at 20:1. MrSID mosaics were compressed at 20:1, 40:1, and 80:1.
Coordinate System: UTM, Zone 16 North
Horizontal Datum: NAD83
Pixel Resolution: 1 meter
Scale: 1:12,000 Individual DOQQsFile Format: BSQ (45 MB/file)
File Format: MrSID (3 MB/file)(2 MB/file)
File Format: GeoTiff and/or IMAGINE (only a few files in this format)DOQQ Mosaics
File Format: MrSID (50-250MB depending on compression ratio)
