Quarter-Quad: Refers to a map sheet size that is one-quarter of a 7.5 minute USGS quadrangle. DOQQ is a digital orthophoto quarter quad, a map product @ 1=1,000' used by the USGS and many statewide programs.
Digital orthophoto quarter-quadrangles will be cast on the North American Datum of 1983 (NAD 83), Universal Transverse Mercator (UTM) projection, with coordinates in meters.
NAPP at 1:40,000-scale, is used for quarter-quadrangle images, while the older NHAP at 1:80,000-scale is used for quadrangle (7.5 minute topographic sheet) coverage.
Digital Orthophoto Quarter-Quad (DOQ) - A 3.75 minute square distortion free image of the surface of the earth. The imagery has been geographically and photographically rectified to remove all distortion, and meet requirements of the USGS.
 See also: DEM, Feature, Aerial Photograph, Digital Image, Cover
  
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