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dc.description.abstractThe U.S. Geological Survey has added the new category of digital orthophotos to the National Digital Cartographic Data Base. This differentially rectified digital image product enables users to take advantage of the properties of current photoimagery as a source of geographic information The product and standard were implemented in July 1992. The digital orthophotos are quadrangle based and cast on the Universal Transverse Mercator projection and extend beyond the primary datum theoretical 3.75-minute or 7.5-minute quadrangle neat line approximately 300 meters to form a rectangle. The oyeredge may be used for mosaicking with adjacent digital orthophotos. To provide maximum information content and utility to the user, metadata (header) records exist at the beginning of the digital orthophoto file. Header information includes the photographic source type, date, instrumentation used to create the digital orthophoto, and information relating to the DEM that was used in the rectification process. The North American Datum of 1983 (NAD 83) is considered the primary datum. Additional header information is included on transformation constants from the 1927 and 1983 North American Datums to the orthophoto internal file coordinates to enable the user to register overlays on either datum. The quadrangle corners in both datums are also imprinted on the image. Flexibility has been built into the digital orthophoto format for future enhancements, such as the provision to include the corresponding digital elevation model elevations used to rectify the orthophoto. The digital orthophoto conforms to National Map Accuracy Standards and provides valuable mapping data that can be used as a tool for timely revision of standard map products, for land use and land cover studies, and as a digital layer in geographic information system.en
dc.titleU.S. geological survey standard for digital orthophotosen
ags.publisherPlaceAddis Ababa :en
ags.publisherNameUN. ECA,en
dc.coverage.spatialAFR
dc.coverage.spatialAfrica
dc.date.accessioned2011-10-11T07:07:43Z
dc.date.available2011-10-11T07:07:43Z
dc.date.issued1993-02
dc.identifier.urihttps://hdl.handle.net/10855/14224
dc.format.extent14 p. :
dc.languageeng
dc.typeConference document
uneca.subject.fulltaxonomyUNBIS::SCIENCE AND TECHNOLOGY::EARTH SCIENCES::GEOLOGICAL SURVEYS
uneca.subject.fulltaxonomyUNBIS::NATURAL RESOURCES AND THE ENVIRONMENT::LAND, PLANT AND SOIL RESOURCES::SOIL SURVEYS
uneca.subject.fulltaxonomyUNBIS::SCIENCES ET TECHNIQUES::SCIENCES DE LA TERRE::LEVES GEOLOGIQUES
uneca.subject.fulltaxonomyUNBIS::CIENCIA Y TECNOLOGIA::CIENCIAS DE LA TIERRA::ESTUDIOS GEOLOGICOS
uneca.subject.fulltaxonomyUNBIS::RESSOURCES NATURELLES ET ENVIRONNEMENT::TERRAINS, RESSOURCES VEGETALES, SOLS::ETUDES PEDOLOGIQUES
uneca.subject.fulltaxonomyUNBIS::RECURSOS NATURALES Y MEDIO AMBIENTE::TIERRAS, RECURSOS VEGETALES Y SUELOS::ESTUDIOS DE SUELOS
uneca.conference.fulltaxonomyConference Categories::Conferences on Surveying, Cartography and Mapping
uneca.workflow.processedtrue
ags.creatorCorporateUnited Nations. Economic and Social Council
ags.creatorCorporateUnited Nations. Economic Commission for Africa
ags.creatorConferenceUN. ECA United Nations Regional Cartographic Conference for Africa (8th : 1993, Feb. 22 - 27 : Addis Ababa, Ethiopia)
ags.subjectThesaurusGEOLOGICAL SURVEYS
ags.subjectThesaurusSOIL SURVEYS
ags.subjectThesaurusLEVES GEOLOGIQUES
ags.subjectThesaurusESTUDIOS GEOLOGICOS
ags.subjectThesaurusETUDES PEDOLOGIQUES
ags.subjectThesaurusESTUDIOS DE SUELOS
ags.subjectClassification03.01.00 Geo-Information
ags.availabilityNumber55704
ags.availabilityNumber1993
ags.availabilityLocationECA-HQ
ags.rights.termsofusepublic
ags.RNE/ECA/NRD/CART/205
ags.JN55704
ags.creatorConferenceCategoryConferences on Surveying, Cartography and Mapping
uneca.language.supporteden


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