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South Dakota DOQQs
1 meter, B/W MrSid Format 99% Statewide Coverage Universal Transverse Mercator NAD83 UTM Zones 13-14 Flown 1991-1999 (see Graphic) General Information: Orthophotos combine the image characteristics of a photograph with the geometric qualities of a map. The primary digital orthophotoquad (DOQ) is a 1-meter ground resolution, quarter-quadrangle (3.75-minutes of latitude by 3.75-minutes of longitude) image cast on the Universal Transverse Mercator Projection (UTM) on the North American Datum of 1983 (NAD83).The geographic extent of the DOQ is equivalent to a quarter-quad plus overedge. The overedge ranges a minimum of 50 meters to a maximum of 300 meters beyond the extremes of the primary and secondary corner points. The overedge is included to facilitate tonal matching for mosaicing and for the placement of the NAD83 and secondary datum corner ticks. The normal orientation of data is by lines (rows) and samples (columns). Each line contains a series of pixels ordered from west to east with the order of the lines from north to south. The standard, archived digital orthophoto is formatted as four ASCII header records, followed by a series of 8-bit binary image data records. The radiometric image brightness values are stored as 256 gray levels ranging from 0 to 255. The metadata provided in the digital orthophoto contain a wide range of descriptive information including format source information, production instrumentation and dates, and data to assist with displaying and georeferencing the image. The distribution format of DOQs will be MRSID compressed images via digital download of 7.5' quadrangles. All four quarter quads are included in one zip file. The reconstituted image from the compressed file will exhibit some radiometric differences when compared to its uncompressed original but will retain the geometry of the uncompressed DOQ. Source Contribution: Panchromatic black and white (or color infra-red) NAPP or NAPP-like photograph. NAPP photographs are centered on the DOQ coverage area. |
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