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2009 Capitol Region Council of Governments Orthophotography

Frequently-asked questions:


What does this data set describe?

Title:
2009 Capitol Region Council of Governments Orthophotography

Abstract:
2009 Capitol Region Council of Governments (CRCOG) Orthophotography is very high resolution, color, leaf off, aerial photography that covers the entire Capitol Region and the Town of Plainville, Connecticut. The coverage area includes the following municipalities in Connecticut - Andover, Avon, Bloomfield, Bolton, Canton, East Granby, East Hartford, East Windsor, Ellington, Enfield, Farmington, Glastonbury, Granby, Hartford, Hebron, Manchester, Marlborough, Newington, Plainville, Rocky Hill, Simsbury, Somers, South Windsor, Suffield, Tolland, Vernon, West Hartford, Wethersfield, Windsor, and Windsor Locks. The ground resolution is 3 inches (0.25 ft) per image pixel and the date of the photography is Spring 2009. The orthophotography is intended to support mapping at 1:1,200 scale (1 inch = 100 feet).

  1. How should this data set be cited?

    Capitol Region Council of Governments (data publisher), Connecticut Office of Policy and Management (data publisher), 20100114, 2009 Capitol Region Council of Governments Orthophotography.

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

    Bounding coordinates:
    West: -72.970871
    East: -72.271451
    North: 42.040870
    South: 41.573368

  3. What does it look like?

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/orthophoto2009crcogcolorfullview.jpg (JPEG)
    Full view of 2009 Capitol Region Council of Governments Orthophotography

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/orthophoto2009crcogcolordetailview.jpg (JPEG)
    Detail view of 2009 Capitol Region Council of Governments Orthophotography 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: 2009
    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 680000 x 760000 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 0.250000.
      Ordinates (y-coordinates) are specified to the nearest 0.250000.
      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?

    2009 Capitol Region Council of Governments Orthophotography
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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?

    WSP SELLS, Inc. was contracted to provide the 2009 Orthophotography.

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

    Erik D. Snowden
    Capitol Region Council of Governments
    241 Main Street
    Hartford, Connecticut 06106-5310
    USA

    860-522-2217 (voice)
    860-724-1274 (FAX)
    esnowden@crcog.org
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Why was the data set created?

In 2008, the Capitol Region Council of Governments received approval for a Regional Performance Initiative (RPI) grant from the Connecticut Office of Policy and Management to acquire orthophotography. The RPI grants are designed to take advantage of economies of scale that can be realized by regional cooperation and coordination of projects in Connecticut. The RPI grant funded the aquisition of 2009 orthophotogy for the entire Capitol Region and the Town of Plainville, for a total of 30 municipalities. Several additional municipalities also contracted with the vendor to acquire orthophotography at reduced cost due to the size and coordination of the flight. The project was managed by CRCOG, with generous assistance from municipal GIS professionals in the region. In particular, the task of reviewing the quality of the orthophotography produced by the vendor was completed by CRCOG staff and these municipal GIS professionals.

This particular aerial survey of color, leaf off, 3 inch pixel resolution orthophotography provides the ability to map a comprehensive set of detailed planimetric data that includes roads, sidewalks, streets, highways, and alleys including curb lines, edge of paved surfaces or edge of traveled way, utility poles, street signs, highway lane and traffic safety markings, and general feature details as building footprints, decks, pools, reservoirs, tanks, docks, piers, airports, bridges, overpasses, underpasses, railroads, parking lots, driveways, other impervious surfaces, streams, lakes, drainage courses, holding basins, shorelines, other watercourses, vegetation outlines, fence lines, drainage, and other similar construction or terrain features.

This is ideal for identifying features on the ground surface in developed, open, and even wooded areas because leaves on trees and shrubs that normally obstruct the view from above are largely absent. For example, features such as stone walls, dirt roads, and other structures in wooded areas are usually visible and identifiable. Areas of deciduous verses coniferous trees are apparent.

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How was the data set created?

  1. Where did the data come from?

    Photo (source 1 of 3)

    WSP SELLS, Inc., Digital Frame Photo.

    Type of source media: Digital Frame Photo
    Source contribution:
    Ultra Cam X

    GeoTIFF (source 2 of 3)

    Capitol Region Council of Governments (data publisher), Connecticut Office of Policy and Management (data publisher), WSP SELLS, Inc. (data collector, data compiler), 2009, 2009 GeoTiff Orthophotos.

    Type of source media: disc

    mosaic (source 3 of 3)

    Capitol Region Council of Governments (data publisher), Connecticticut Office of Policy and Management (data publisher), 20100114, 2009 Capitol Region Council of Governments Orthophotography.

    Type of source media: disc

  2. What changes have been made?

    Date: 20100114 (change 1 of 1)
    Using ESRI ArcGIS 9.3.1 software, an empty raster dataset was created and subsequently populated with input rasters to create a raster mosaic. The State of Connecticut, Department of Environmental Protection obtained these TIFF images from the Capitol Region Council of Governments.
    
    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 25. 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:\Connecticut_Ortho_2009_CRCOG.gdb
    Ortho_2009_Color_CRCOG # 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 25" "687800 1015180" C:\Connecticut_Ortho_2009_CRCOG.gdb\Ortho_2009_Color_CRCOG
    
    STEP 2 - Mosaic input rasters. The Ignore Background Value was not set. 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. Below is an example of a mosaic of one GeoTiff.
    
    Mosaic F:\CRCOG_Orthos\All\772510775.TIF; F:\CRCOG_Orthos\All\772510825.TIF C:\Connecticut_Ortho_2009_CRCOG.gdb\Ortho_2009_Color_CRCOG LAST FIRST # # NONE 0 C:\Connecticut_Ortho_2009_CRCOG.gdb\Ortho_2009_Color_CRCOG NONE

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

    860-424-3540 (voice)

    Data sources used in this process:
    • GeoTiff

    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?

    ASPRS Class I

  2. How accurate are the geographic locations?

    ASPRS Class 1. The orthophotography is intended to support mapping at 1:1,200 scale (1 inch = 100 feet).
    
    

  3. How accurate are the heights or depths?

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

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

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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: None. The data is in the public domain and may be redistributed. Please include this metadata record in any redistributions.
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 Captitol Region Council of Governments.

Distributor 1 of 1

  1. Who distributes the data set?

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

    2009 Capitol Region Council of Governments Orthophotography

  3. What legal disclaimers am I supposed to read?

  4. How can I download or order the data?

  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?

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Who wrote the metadata?

Dates:
Last modified: 20110119

Metadata author:
Erik D. Snowden
Capitol Region Council of Governments
241 Main Street
Hartford, Connecticut 06106-5310
USA

860-522-2217 (voice)
860-724-1274 (FAX)
esnowden@crcog.org

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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