Abstract: A digital orthophoto is a raster image of remotely sensed data in which displacement in the image due to sensor orientation and terrain relief have been removed. Orthophotos combine the image characteristics of a photograph with the geometric qualities of a map. The primary digital orthophoto quad (DOQQ) 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 DOQQ 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 mosaicking 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 standard distribution format of the DOQQs will be JPEG compressed images on CD-ROM by counties or special regions. The reconstituted image from the CD-ROM will exhibit some radiometric differences when compared to its uncompressed original but will retain the geometry of the uncompressed DOQQ. Uncompressed DOQQs are distributed on tape. This digital orthophoto quarter-quadrangle has been projected from UTM coordinate system zones 16 or 17, NAD83, using meters as units into Ohio State Plane Coordinate System North of South zones, using US survey feet as units. This quarter-quadrangle has been converted to compressed MrSid format with an associated SDW file.
Purpose: DOQQs serve a variety of purposes, from interim maps to field references for earth science investigations and analysis. The DOQQ is useful as a layer of a geographic information system and as a tool for revision of digital line graphs and topographic maps.
Supplemental Information: This metadata record was developed from a metadata template developed from Appendix A of the FGDC-STD-008-1999 document Content Standards for Digital Orthoimagery Subcommittee on Base Cartographic Data Federal Geographic Data Committee. Appendix A, was included in the above referenced document as an example of a metadata file for a specific orthoimage. The Appendix was run through CNS and MP to generate an FGDC Version 2 metadata record. The record was then stripped of most time, UTM Zone number and file specific data to produce the DOQQ metadata template. Thesauri used to compose place name keywords: U.S. Department of Commerce, 1977, Countries, dependencies, areas of special sovereignty, and their principal administrative divisions (Federal Information Processing Standard 10-3): Washington, D.C., National Institute of Standards and Technology. U.S. Department of Commerce, 1987, Codes for the identification of the States, the District of Columbia and the outlying areas of The United States, and associated areas (Federal Information Processing Standard 5-2): Washington, D. C., National Institute of Standards and Technology. U.S. Department of Commerce, 1990, Counties and equivalent entities of The United States, its possessions, and associated areas (Federal Information Processing Standard 6-4): Washington, D.C. National Institute of Standards and Technology.

Progress: complete
Update Frequency: None Planned

Theme Keywords: None, DOQ, DOQQ, digital orthophoto, digital orthophoto quad, digital image map, aerial photograph, rectified photograph, rectified image, orthophoto, quarter-quadrangle orthophoto, 1-meter orthophoto, 2-meter orthophoto, 3.75- x 3.75-minute orthophoto, 7.5- x 7.5-minute orthophoto, imageryBaseMapsEarthCover
Place Keywords: US, Ohio, FREDERICKTOWN SW

Access Constraints: None
Usage Constraints: None. Acknowledgement of publisher would be appreciated in products derived from these data