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USGS 2008 High Resolution Orthoimagery for the Bridgeport, Hartford, and New Haven, Connecticut Urban Areas

Frequently-asked questions:


What does this data set describe?

Title:
USGS 2008 High Resolution Orthoimagery for the Bridgeport, Hartford, and New Haven, Connecticut Urban Areas

Abstract:
This is a raster mosaic of 2008, natural color, leaf off, 1 ft ground sample distance imagery from the U.S. Geological Survey for the Bridgeport, Hartford and New Haven, Connecticut Urban Areas. Imagery only exists for these three geographic regions.

This task order consists of digital orthophoto production covering the CT Cities 133 Urban Area footprint. 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.

Supplemental information:
The raster mosaic of 2008 USGS Urban Area Orthoimagery was prepared by the State of Connecticut, Department of Environmental Protection (CT DEP) using data provided by the USGS. The original input rasters are in GeoTIFF format and in NAD 1983 UTM Zone 18N Meters. These data are also available online from USGS National Map Seamless Server. The individual rasters were projected to NAD 1983 StatePlane Connecticut FIPS 0600 Feet and merged together in the resulting mosaic for the Bridgeport, Hartford, and New Haven Connecticut Urban Areas.

The data obtained through The National Map Seamless Server is considered to be the "best available" data from USGS. Historical data and other data may be obtained by contacting Customer Services, Earth Resources Observation and Science Center at 1-800-252-4547. Information in quotation marks, initial processing steps, accuracy reports, and source information is taken directly from the original metadata. Spatial-specific information not available

  1. How should this data set be cited?

    U.S. Geological Survey, State of Connecticut, Department of Environmental Protection, 20091005, USGS 2008 High Resolution Orthoimagery for the Bridgeport, Hartford, and New Haven, Connecticut Urban Areas: Urban Area Orthoimagery0.1, U.S. Geological Survey, Sioux Falls, SD.

    Online links:
  2. What geographic area does the data set cover?

    Bounding coordinates:
    West: -73.773334
    East: -72.111624
    North: 42.009657
    South: 40.991646

  3. What does it look like?

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/orthophoto2008usgsurbanareafullview.gif (GIF)
    Full view of USGS High Resolution Orthoimagery for the Bridgeport, Hartford, and New Haven, Connecticut Urban Areas

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/orthophoto2008usgsurbanareadetailview.gif (GIF)
    Detail view of USGS High Resolution Orthoimagery for the Bridgeport, Hartford, and New Haven, Connecticut Urban Areas within vicinity of the Connecticut Department of Environmental Protection building at 79 Elm Street in Hartford, Connecticut.

  4. Does the data set describe conditions during a particular time period?

    Calendar date: 200804
    Currentness reference:
    ground condition

  5. What is the general form of this data set?

    Geospatial data presentation form: Fgdb raster digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Raster data set. It contains the following raster data types:
      • Dimensions 365777 x 447307 x 1, type Pixel

    2. What coordinate system is used to represent geographic features?

      The map projection used is Lambert Conformal Conic.

      Projection parameters:
      Lambert Conformal Conic
      Standard parallel: 41.200000
      Standard parallel: 41.866667
      Longitude of central meridian: -72.750000
      Latitude of projection origin: 40.833333
      False easting: 999999.999996
      False northing: 499999.999998

      Planar coordinates are encoded using row and column.
      Abscissae (x-coordinates) are specified to the nearest 1.009689.
      Ordinates (y-coordinates) are specified to the nearest 1.009689.
      Planar coordinates are specified in survey feet.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical coordinate system definition:
      Altitude system definition:
      Altitude resolution: 1.000000
      Altitude encoding method: Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    Entity and attribute overview:
    Natural color orthoimagery is organized in three color bands or channels which represent the red, green, and blue portions of the spectrum. Each image pixel is assigned a triplet of numeric values, one for each color band. Numeric values range from 0 to 255. Areas where data is incomplete due to lack of full image coverage are represented with the numeric value of 0.

    Entity and attribute detail citation:
    U.S. Department of the Interior, U.S. Geological Survey, 1999, Standards for Digital Orthoimagery: Reston, VA
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Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)


  2. Who also contributed to the data set?

    U.S. Geological Survey and Aero-Metric, Inc.
    

  3. To whom should users address questions about the data?

    Customer Services Representative
    U.S. Geological Survey
    USGS Earth Resources Observation and Science Center
    47914 252nd Street
    Sioux Falls, SD 57198-0001
    USA

    605/594-6151 (voice)
    1-800-252-4547 (voice)
    605/594-6589 (FAX)
    custserv@usgs.gov
    Hours of Service: 0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)
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Why was the data set created?

High Resolution Orthoimagery provides a critical tool for those involved in development decisions such as resource managers and city planners. The detailed focus of High Resolution Orthoimagery provides emergency responders critical information in determining the best evacuation routes, alternative routes and safe access to aid. High Resolution Orthoimagery assists law enforcement personnel in determining the best locations to place surveillance cameras in high-traffic urban areas and popular attractions. A digital orthoiamge is a geometrically accurate photographic record of landscape conditions at the time of the corresponding aerial photography. As such, the digital orthoimage is useful for a variety of applications, such as environmental monitoring, facility engineering/maintenance, city/county planning, property line review, etc. The digital orthoimage can be used alone or as a raster basemap for corresponding vector line mapping. The data assists Federal, State and local emergency responders in planning for homeland security efforts. This data also supports The National Map.

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How was the data set created?

  1. Where did the data come from?

    Image (source 1 of 5)

    Aero-Metric, Inc., 2008, 028014.

    Type of source media: stable-base material
    Source scale denominator: 21,600
    Source contribution:
    Source imagery for orthophoto production.

    DEM (source 2 of 5)

    U.S. Geological Survey, 2008, USGS DEM.

    Type of source media: CD-ROM
    Source contribution:
    Used to provide ground elevations for orthorectification process.

    AT (source 3 of 5)

    Aero-Metric, Inc., 2008, CT Cities Aerotriangulation.

    Type of source media: CD-ROM
    Source contribution:
    Used to provide photo exterior orientations for orthorectification process.
    

    TIFF (source 4 of 5)

    U.S. Geological Survey, 2008, TIFF Orthophotos of USGS 2008 High Resolution Orthoimagery for the Bridgeport, Hartford, and New Haven, Connecticut Urban Areas: Urban Area Orthoimagery0.1, U.S. Geological Survey, Sioux Falls, SD.

    Online links:
    Type of source media: disk

    mosaic (source 5 of 5)

    U.S. Geological Survey, State of Connecticut, Department of Environmental Protection, 2009, USGS 2008 High Resolution Orthoimagery for the Bridgeport, Hartford, and New Haven, Connecticut Urban Areas: Urban Area Orthoimagery0.1, U.S. Geological Survey, Sioux Falls, SD.

    Online links:
    Type of source media: disk
    Source contribution:
    Statewide mosaic of all Orthophoto TIFFS

  2. What changes have been made?

    Date: 200812 (change 1 of 3)
    The raw scanned photos were aerotriangulated to support digital ortho image production for the CT Cities project area. Airborne GPS and ground check point data was provided by AERO-METRIC, Inc. The project was referenced to the North American Datum of 1983 (NAD83), Universal Transverse Mercator, Zone 18 horizontally and to the North American Vertical Datum of 1988 (NAVD88) vertically. Units were in meters.The scanned images (14 micron), ABGPS data, ground check point data, and camera calibration data were used as inputs to the Zeiss/Intergraph ImageStation Automatic Triangulation (ISAT) softcopy program. ISAT correlated image points and aerotriangulated the block of images to create exposure station exterior orientations. All ground checkpoints were manually measured on the imagery. These ground checkpoints were included in the aerotriangulation adjustments as unconstrained points for absolute ground location verification.The scale of the aerial photos was 1:21,600. The photography was exposed on 4/2/08, 4/3/08 and 4/8/08.Rectification was done using the aerotriangulation data, scans, NED data. These rectified images were used to draw seamlines. The images were then dodged. The dodged rectified images were mosaicked, balanced, and cut into final image sheets. The final sheets were viewed and artifacts were removed as well as other edits performed.
    

    Data sources used in this process:
    • Image
    • DEM
    • AT

    Data sources produced in this process:
    • TIFF

    The metadata were imported and updated for display through The National Map Seamless Server at http://seamless.usgs.gov Project level metadata are available in several formats: HTML, TEXT, XML, FAQ and SGML.
    

    Person responsible for change:
    Customer Service Representative
    U.S. Geological Survey
    USGS Earth Resources Observation and Science Center
    47914 252nd Street
    Sioux Falls, SD 57198-0001
    USA

    605-594-6151 (voice)
    1-800-252-4547 (voice)
    605-594-6589 (FAX)
    custserv@usgs.gov
    Hours of Service: 0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)
    Contact Instructions:
    The USGS point of contact is for questions relating only to the data display and download from this web site. For questions regarding data content and quality, refer to original processor.

    Data sources used in this process:
    • TIFF

    Data sources produced in this process:
    • TIFF

    Date: 20091005 (change 3 of 3)
    Using ESRI ArcGIS 9.3.1 software, an empty raster dataset was created and subsequently populated with input rasters to create a statewide raster mosaic. The State of Connecticut, Department of Environmental Protection obtained these TIFF images from the U.S. Geological Survey.
    
    STEP 1 - Create Raster Dataset - The Coordinate System for the raster dataset is NAD_1983_StatePlane_Connecticut_FIPS_0600_Feet. The image compression type is JPEG with a compression quality of 90. The Pyramid Reference Point X and Y coordinate are 687800 and 1015180, respectively. Bands: 3. Pyramids: 8 Bilinear. The Pixel Type is 8_BIT_UNSIGNED, which supports index values from 0 to 255. Raster statistics were not built. Below is a record of the ESRI Geoprocessing CreateRasterDataset command and arguments that created the empty raster dataset. 
    
    CreateRasterDataset C:\CT\2008\Connecticut_Ortho_2008_Urban_Area.gdb Ortho_2008_Color_USGS_Urban_Area # 8_BIT_UNSIGNED PROJCS['NAD_1983_StatePlane_Connecticut_FIPS_0600_Feet',
    GEOGCS['GCS_North_American_1983',\
    DATUM['D_North_American_1983',
    SPHEROID['GRS_1980',6378137.0,298.257222101]],
    PRIMEM['Greenwich',0.0],
    UNIT['Degree',0.0174532925199433]],
    PROJECTION['Lambert_Conformal_Conic'],
    PARAMETER['False_Easting',999999.999996],
    PARAMETER['False_Northing',499999.999998],
    PARAMETER['Central_Meridian',-72.75],
    PARAMETER['Standard_Parallel_1',41.2],
    PARAMETER['Standard_Parallel_2',41.86666666666667],
    PARAMETER['Latitude_Of_Origin',40.83333333333334],
    UNIT['Foot_US',0.3048006096012192]]
    3 # "PYRAMIDS 8 BILINEAR" "128 128" "JPEG 90" "687800 1015180" C:\CT\2008\Connecticut_Ortho_2008_Urban_Area.gdb\Ortho_2008_Color_USGS_Urban_Area
    
    STEP 2 - Mosaic input rasters for the Bridgeport, Hartford, and New Haven Urban Area. The Ignore Background Value was set to one (1). The NoData value was left blank. The Mosaicking Tolerance value was set to zero (0). Consequently, pixel values in the raster mosaic resulted from a resampling of pixels values from individual input rasters due to the difference in alignment of input and mosaic (target) pixels. Note, in the resulting mosaic, the input rasters in NAD 1983 UTM Zone 18N Meters were projected to NAD 1983 StatePlane Connecticut FIPS 0600 Feet. Below is an example usage of the ESRI Geoprocessing Mosaic command and arguments used to mosaic 4 input rasters in TIFF format.
    

    Person responsible for change:
    Howie Sternberg
    State of Connecticut, Department of Environmental Protection
    79 Elm Street
    Hartford, Connecticut 06106
    USA

    860-424-3540 (voice)
    860-424-4058 (FAX)
    dep.gisdata@po.state.ct.us
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time

    Data sources used in this process:
    • TIFF

    Data sources produced in this process:
    • mosaic

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How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Radiometry is verified by visual inspection of the digital orthophoto. Slight systematic radiometric differences may exist between adjacent orthoimage files; these are due primarily to differences in source image capture dates and sun angles along flight lines. These differences can be observed in an image's general lightness or darkness when it is compared to adjacent orthoimage file coverages. Tonal balancing may be performed over a group of images during the mosaicking process which may serve to lighten or darken adjacent images for better color tone matching.

  2. How accurate are the geographic locations?

    The relative accuracy is assembled by comparing rectified images generated from adjacent strips of imagery. The absolute accuracy is assessed by measuring the ground control points in the rectified image against the actual surveyed co-ordinate position. The testing is for overall accuracy. This data has been produced to be fully compliant with the National Map Accuracy Standards (NMAS) for mapping at this scale.

  3. How accurate are the heights or depths?

    There is no vertical accuracy component to orthophotography.

  4. Where are the gaps in the data? What is missing?

    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.

  5. How consistent are the relationships among the observations, including topology?

    GeoTIFFs conform to the specifications set forth by the USGS for production of 133 UA orthophotos.
    

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How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access constraints: Any downloading and use of these data signifies a user's agreement to comprehension and compliance of the USGS Standard Disclaimer. Insure all portions of metadata are read and clearly understood before using these data in order to protect both user and USGS interests.
Use constraints:
There is no guarantee of warranty concerning the accuracy of the data. Users should be aware that temporal changes may have occurred since this data set was collected and that some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. Acknowledgement of the originating agencies would be appreciated in products derived from these data. Any user who modifies the data is obligated to describe the types of modifications they perform. User specifically agrees not to misrepresent the data, nor to imply that changes made were approved or endorsed by the U.S. Geological Survey. Please refer to http://www.usgs.gov/privacy.html for the USGS disclaimer.

Distributor 1 of 2 <Next>

  1. Who distributes the data set?

    Customer Services Representative
    U.S. Geological Survey
    Earth Resources Observation and Science Center
    47914 252nd Street
    Sioux Falls, SD 57198-0001
    USA

    605/594-6151 (voice)
    1-800-252-4547 (voice)
    605/594-6589 (FAX)
    custserv@usgs.gov
    Hours of Service: 0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)
    Contact Instructions:
    The USGS point of contact is for questions relating only to the data display and download from this web site. For questions regarding data content and quality, refer to the original processor.

  2. What's the catalog number I need to order this data set?

    USGS 2008 High Resolution Orthoimagery for the Bridgeport, Hartford, and New Haven, Connecticut Urban Areas

  3. What legal disclaimers am I supposed to read?

    Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made by the USGS regarding the use of the data on any other system, nor does the act of distribution constitute any such warranty. Data may have been compiled from various outside sources. Spatial information may not meet National Map Accuracy Standards. This information may be updated without notification. The USGS shall not be liable for any activity involving these data, installation, fitness of the data for a particular purpose, its use, or analyses results.
    

  4. How can I download or order the data?

    • Availability in digital form:


    • Data format:
      Natural Color in format TIFF (version ArcGIS 9.3) Raster Size: 0.001
      Network links: http://seamless.usgs.gov
      Media you can order: CD-ROM(format ISO 9660 Mode 1 Level 2 Extensions)

    • Cost to order the data: None


    • How long will it take to get the data?

      Variable

  5. Is there some other way to get the data?

  6. What hardware or software do I need in order to use the data set?

    ESRI ArcGIS Suite and/or Arc/Info or other compatible software, and supporting operating systems.


Distributor 2 of 2 <Back>

  1. Who distributes the data set?

    State of Connecticut, Department of Environmental Protection
    79 Elm Street
    Hartford, Connecticut 06106
    USA

    860-424-3540 (voice)
    860-424-4058 (FAX)
    dep.gisdata@po.state.ct.us
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time

  2. What's the catalog number I need to order this data set?

    USGS 2008 High Resolution Orthoimagery for the Bridgeport, Hartford, and New Haven, Connecticut Urban Areas

  3. What legal disclaimers am I supposed to read?

    Although these data have been used by the State of Connecticut, no warranty, expressed or implied, is made by the State of Connecticut as to the accuracy of these data and or related materials.  The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata.

  4. How can I download or order the data?

    • Availability in digital form:


    • Data format:
      Natural Color in format File Geodatabase Raster Dataset (statewide mosaic) (version 9.3) Raster Dataset
      Media you can order: disk

    • Cost to order the data: An offline copy of the data may be accessed without charge


  5. Is there some other way to get the data?

    The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.

  6. What hardware or software do I need in order to use the data set?

    Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information.

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Who wrote the metadata?

Dates:
Last modified: 20090227

Metadata author:
Customer Services Representative
U.S. Geological Survey (Original metadata provided by USDA was modified by Howie Sternberg of CT DEP to document the process undertaken to create and distribute a statewide mosaic)
USGS Earth Resources Observation and Science Center
47914 252nd Street
Sioux Falls, SD 57198-0001
USA

605/594-6151 (voice)
1-800-252-4547 (voice)
605/594-6589 (FAX)
custserv@usgs.gov
Hours of Service: 0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)
Contact Instructions:
The above is the contact information for the Earth Resources Observation and Science Center in Sioux Falls, SD. This is the digital data storage and distribution center for the USGS.

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata(FGDC-STD-001-1998)

Metadata extensions used:
  • http://www.esri.com/metadata/esriprof80.html

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