The District of Columbia

IMAGE.ORTHO2002

IMAGE.ORTHO2002

by U.S. Geological Survey

Keywords
About: mosaic, orthoimage, natural color orthoimage, rectified photograph, imageryBaseMapsEarthCover
Taking place at: US, United States, Washington Dc, Dc, Maryland, MD, Virginia, VA, West Virginia, WV, Alexandria, Anacostia, Annandale, Annapolis, Arcola, Ashby Gap, Baltimore East, Baltimore West, Barren Island, Beltsville, Benedict, Betterton, Blackwater River, Bluemont, Bowie, Brandy Station, Brandywine, Bristol, Broomes Island, Buckeystown, Cambridge, Catlett, Centreville, Chancellorsville, Charles Town, Charlotte Hall, Chestertown, Chicamoacomico River, Church Creek, Church Hill, Claiborne, Clarksville, Cockeysville, Colonial Beach North, Cov e Point, Curtis Bay, Dahlgren, Damascus, Deale, Earleville, East New Market, Easton, Edgewood, Ellicott City, Fairfax, Falls Churc, Finksburg, Fort Belvoir, Fowling Creek, Frederick, Fredericksburg, Gainesbille, Gaithersburg, Galena, Germanna Bridge, Germantown, Gibson Island, Golden Hill, Guinea, Gunpowder Neck, Hanesville, Harpers Ferry, Herndon, Hollywood, Honga, Hudson, Hughesville, Independent Hill, Indian Head, Jeffersonton, Joplin, Keedysville, Kensington, Kent Island, King George, La Plata, Langford Creek, Lanham, Laurel, Leesburg, Leonardtown, Libertytown, Lincoln, Love Point, Lower Marlboro, Manassas, Marshall, Mathais Point, Mechanicsbille, Middle River, Middleburg, Middletown, Midland, Mine Run, Mount Vernon, Nanjemoy, Nanticoke, Nokesville, North Beach, Occoquan, Odenton, Orlean, Oxford, Passapatanzy, Perryman, Piscataway, Point of Rocks, Poolesville, Popes Creek, Port Tobacco, Preston, Price, Prince Frederick, Purcellville, Quantico, Queenstown, Rappahannock Academy, Rectortown, Reisterstown, Relay, Remington, Richardsville, Ridgely, Rock Hall, Rock Point, Rockville, Round Bay, Round Hill, Saint Michaels, Salem Church, Sandy Spring, Savage, Seneca, Shepherdstown, Solomons Island, Somerville, South River, Sparrows Point, Spesutie, Stafford, Sterling, Storck, Swan Point, Sykesville, Taylor Island, Thoroughfare Gap, Tilghman, Towson, Trappe, Upper Marlboro, Upperville, Urbana, Vienna, Walkersville, Warrenton, Washington East, Washington West, Waterford, White Marsh, Widewater, Winfield, Wingate, Woodbine, Wye Mills

Abstract

An orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map. For this dataset, the natural color orthoimages were produced at 0.3-meter pixel resolution (approximately 1-foot). The design accuracy is estimated not to exceed 3-meter diagonal RMSE (2.12m RMSE in X or Y). Each orthoimage provides imagery for a 1500- by 1500-meter block on the ground. The projected coordinate system is UTM with a NAD83 datum. There is no image overlap been adjacent files. The naming convention is based on the U.S. National Grid (USNG), taking the coordinates of the SW corner of the orthoimage.

Each GeoTiff file is a mosaic of orthoimages covering a USGS quarter-quadrangle. The index of orthoimage chips for each USGS quarter-quadrangle is in the file ortho_quad_index.mxd.

Purpose

The quarter-quadrangle mosaics of orthoimage chips were created as part of an implementation of The National Map (TNM) to provide large-scale imagery of the area.

Access constraints

None

Use constraints

None. Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from these data.

Point of contact


in U.S. Geological Survey, Eastern Region Geography

521 National Center
Reston VA, 20192, USA

phone: 703 648-6287
fax: 703 648-4603

Credits

Cassandra Ladino & Sharon Hamann worked on mosaicking the orthophotos into the 7.5-minute quads and prepared the indexes.

Data accuracy

Logical consistency
All GeoTIFF tagged data and image file sizes are validated using commercial GIS software to ensure proper loading before being archived. This validation procedure ensures correct physical format and field values for tagged elements. Seamlines and tile edges are visually inspected. Seamline mismatches are not corrected unless the overall displacement exceeds one meter.

Completeness
Orthoimages are visually inspected for completeness to ensure that no gaps or image misplacements exist within and between adjacent images. These images are derived by mosaicking multiple images to ensure complete coverage. Source imagery is cloud free. Photography was flown during leaf-off in deciduous vegetation regions. Coastal areas and international boundary regions may have areas without images (void areas) in parts of the coverage. These void areas have a radiometric value of either zero (black) or 128 (uniform gray).

Horizontal positional accuracy
Compliance with the accuracy standard was ensured by the placement of photo identifiable ground control points and the collection of airborne GPS data. The elevation data were generated by autocorrelation and manual processes. An RMS value for each tile was calculated based on the photos utilized in the production of the tile by comparing the aerotriangulation (AT) X and Y coordinates. This value represents an estimate of the accuracy of the horizontal coordinate measurements in the tile expressed in meters. No further processing was done on the orthoimages to affect the accuracy.

Lineage / Sources

  • Orthoimages for the Washington DC area
    digital raster file, The original imagery came from true color stable-base aerial photography film flown at 7,500 feet above average ground elevation. The digital raster files for each orthoimage chip provide imagery used in the digital orthoimage.
    orthoimages
    by U.S. Geological Survey, 1994
Lineage / Processes
GIS Data Coordinator
in Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

fax: 202-727-1761
hours: 8:30am - 5:30pm
OCTO GIS staff reprojected the orthophoto from UTM Zone 18 to Maryland 1983/91 State Plane, coordinates in meters, to conform to the District projection standard. Then, staff compressed the newly projected ortho using Mr. SID using a 23:1 ratio to make the image under 700MB in size.

Distribution

Contact EDC for other off-line media or information on other media types.

Distribution liability
Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made by the USGS regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. The USGS will warrant the delivery of this product in computer-compatible format and will offer appropriate adjustment of credit when the product is determined unreadable by correctly adjusted computer input peripherals or when the physical medium is delivered in damaged condition. Requests for adjustment of credit must be made within 90 days from the date of this shipment from the ordering site.

Distributed by

in U. S. Geological Survey, EROS Data Cemter

47914 252nd Street
Sioux Falls SD, 57198-0001, USA

phone: 1-800-252-4547
fax: 605-594-6589
hours: Monday - Friday, 0800-1600 Central Time

Entity

Band_1

Attributes

  • ObjectID / ESRI
    Internal feature number.
  • Value
  • Count

Entity

Band_2

Attributes

  • ObjectID / ESRI
    Internal feature number.
  • Value
  • Count

Entity

Band_3

Attributes

  • ObjectID / ESRI
    Internal feature number.
  • Value
  • Count

Metadata

FGDC Content Standards for Digital Geospatial Metadata / FGDC-STD-001-1998 as of 12/14/2007

Provided by
REQUIRED: The person responsible for the metadata information.
in U.S. Geological Survey

521 National Center
Reston VA, 20192,

phone: 703 648-6287
fax: 703 648-4603