DIGITAL ORTHOPHOTO QUADRANGLES
Source: Nebraska Department of Natural Resources|
Processed by: Data Bank (JH)
Digital Orthophoto Quadrangle (DOQ)
A digital orthophoto quadrangle is a remotely sensed image data for a quadrangle in which displacement of features caused by terrain relief and sensor orientation have been mathematically removed. An orthophoto thus combines the image characteristics of a photograph with the geometric qualities of a map.
A quadrangle is a 7.5 -minute x 7.5 -minute region that conforms to 7.5 minute of latitude and 7.5 minute of longitude on the earth surface as designated by USGS on its topographic maps. A quarter-quadrangle is a 3.75 x 3.75 minute of associated earth's topography.
Availability of DOQs (1999 NAPP)
The Nebraska Department of Natural Resources, in cooperation with the U. S. Geological Survey, developed DOQs based on 1999 NAPP imagery and second generation of 10-meter DEMs.
The 1999 DOQs are developed both in UTM and State Plane coordinate systems referenced to North American Datum of 1983. The coordinate distances are published in meters for UTM and both meters and feet for the State Plane system.
Availability of DOQs (1993 NAPP)
A grayscale DOQ requires about 46 MB of storage space per 3.75- minute quarter quadrangle. It is a voluminous amount of data required to be transmitted for each DOQ. The DOQs are therefore, available upon request only from the Nebraska Department of Natural Resources. The proccessed data (NAD 83, UTM projections) is shipped and copied onto a CD media or 8mm data tapes. Also, each DOQ coverage comes with associated header data embedded into it. The DOQs are disseminated in two forms.
Sample of DOQ coverage
Sample and explanation of Header File
Software for DOQs
Quadrangle Identification Map (28" X 45")
Comments and Suggestions