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Identification Information Download XML Metadata
TitleDOQQ Boundaries
Date Typepublication
Organization NameU.S. Geological Survey
Role originator
Presentation Form mapDigital
Abstract 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 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 DOQs 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 DOQ. Uncompressed DOQs are distributed on tape.
Purpose DOQ's serve a variety of purposes, from interim maps to field references for earth science investigations and analysis. The DOQ is useful as a layer of a geographic information system and as a tool for revision of digital line graphs and topographic maps.
Status onGoing
Descriptive Keywords rectified photograph, DOQQ, 7.5- x 7.5-minute orthophoto, 1-meter orthophoto, digital orthophotoquad, aerial photograph, 2-meter orhtophoto, orthophoto, 3.75- x 3.75-minute orthophoto, rectified image, DOQ, quarter-quadrangle orthophoto, digital image map, digital orthophoto, Land Grids, FIPS code of State or Province, FIPS code for county or counties., MX, US, CA
Access Constraints otherRestrictions
Other Constraints access constraints: None
Use Constraints otherRestrictions
Other Constraints
Topic Category Code
Geographic Bounding Box
North bound latitude
West bound longitudeEast bound longitude
South bound latitude
Distribution Information
Individual Name
Organization NameEarth Science Information Center, U.S. Geological Survey
Position Name
Postal Code20192
Electronic mail address
Hours of Service0800-1600
FeesThe cost for these CD-ROM products is available at: <URL:http://edcwww.cr.usgs.gov/glis/hyper/order_info/prices#DOQ_COUNTY>
Ordering InstructionsDataset searching and ordering capabilities are available through the Global Land Information System (GLIS) at: <URL:http://edcwww.cr.usgs.gov/webglis>
Transfer Size5
Spatial Representation Information
Geometric Object Typecomplex
Geometric Object Count5048
Reference System
Data Quality
Evaluation MethodAll DOQ header data and image file sizes are validated by the Tape Validation System (TVS) software prior to archiving in the National Digital Cartographic Data Base (NDCDB). This validation procedure assures correct physical format and field values for header record elements. Logical relationships between header record elements are tested.
Topological Consistency
Absolute Positional AccuracyThe DOQ horizontal positional accuracy and the assurance of that accuracy depend, in part, on the accuracy of the data inputs to the rectification process. These inputs consist of the digital elevation model (DEM),aerotriangulation control and methods, the photo source camera calibration, scanner calibration, and aerial photographs that meet National Aerial Photography Program (NAPP) standards. The vertical accuracy of the verified USGS format DEM is equivalent to or better than a USGS level 1 or 2 DEM, with a root mean square error (RMSE) of no greater than 7.0 meters. Field control is acquired by third order class 1 or better survey methods sufficiently spaced to meet National Map Accuracy Staandards (NMAS) for 1:12,000-scale products. Aerial cameras have current certification from the USGS, National Mapping Division, Optical Science Laboratory. Test calibration scans are performed on all source photography scanners.
Attribute AccuracyDuring photographic reproduction of the source photography, limited analog dodging is performed to improve image quality. Analog dodging consists of holding back light from certain areas of the sensitized photographic material to avoid overexposure. The diapositive is inspected to insure clarity and radiometric uniformity. Diapositive image brightness values are collected with a minimum of image quality manipulation. Image brightness values may deviate from brightness values of the original imagery due to image value interpolation during the scanning and rectification processes. Radiometry is verified by visual inspection of the digital orthophoto quadrangle with the original unrectified image to determine if the digital orthophoto has the same or better image quality as the original unrectified input image. Slight systematic radiometric differences can be detected between adjacent DOQ files due primarily to differences in source photography capture dates and sun angles of aerial photography along flight lines. These differences can be observed in an image's general lightness or darkness when compared to adjacent DOQ file coverages.
Process StepMetadata imported.
SourceElevation data in the form of an ortho-DEM regridded to user-specified intervals and bounds.
Responsible PartyU.S. Geological Survey
Metadata StandardISO 19115:2003/19139