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Connecticut 2004 Orthophoto Tile Index by Town

Frequently-asked questions:


What does this data set describe?

Title:
Connecticut 2004 Orthophoto Tile Index by Town

Abstract:
Connecticut 2004 Orthophoto Tile Index by Town is a polygon feature class that identifies the location of each Connecticut 2004 orthophoto image tile relative to Connecticut towns. These data are the result of a spatial combination (union) of the Connecticut 2004 orthophoto index with Connecticut town areas. There is one polygon feature for each orthophoto-town combination, with a total of 5,654 orthophoto-town polygon features in the entire feature class. These data include information for all orthophotos, including those located in Connecticut as well as a small number of orthophotos located entirely out of state along the Connecticut state boundary. Each polygon feature record identifies the orthophoto by orthophoto tile name and Connecticut town by official town number and name.

  1. How should this data set be cited?

    State of Connecticut, Department of Environmental Protection (data editor and publisher), State of Connecticut, Department of Transportation (data publisher), 20060821, Connecticut 2004 Orthophoto Tile Index by Town: State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

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

    Bounding coordinates:
    West: -73.744442
    East: -71.761214
    North: 42.065477
    South: 40.978164

  3. What does it look like?

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/orthoindex2004tiletownfullview.gif (GIF)
    Full view of 2004 Orthophoto Tile Index By Town

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/orthoindex2004tiletowndetailview.gif (GIF)
    Detail view of 2004 Orthophoto Tile Index By Town. Note the 1:24,000-scale municipal (town) boundary and shoreline features are incorporated into this index, allowing for easy identification of and selection of orthophoto tiles that cover the geographic extent of individual Connecticut towns.

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

    Calendar date: 2004
    Currentness reference:
    Date of photography

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

    Geospatial data presentation form: vector digital data

  6. How does the data set represent geographic features?

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

      Indirect spatial reference:
      The ORTHOPHOTO_TILE attribute value (e.g. 0420730012_6) identifies the orthophoto tile. The QUADRANGLE, QUAD_NO and QUAD_SEC attribute values describe the number (e.g. 1), name (e.g. Bashbish Falls) and section (e.g. SE) of the 1:24,000-scale USGS topographic quadrangle map that the orthophoto tile polygon feature is located in. The TOWN_NO and TOWN attributes specify the number (e.g. 122) and name (e.g. Salisbury) of the Connecticut town (municipality) the orthophoto tile polygon feature is located in.

      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • G-polygon (5917)

    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 coordinate pair.
      Abscissae (x-coordinates) are specified to the nearest 0.000250.
      Ordinates (y-coordinates) are specified to the nearest 0.000250.
      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?

    Connecticut 2004 Orthophoto Tile Index by Town
    Orthophoto-town footprint. One polygon feature per orthophoto-town combination. (Source: State of Connecticut, Department of Environmental Protection)

    OBJECTID
    Internal feature number. (Source: ESRI)
                      

    Sequential unique whole numbers that are automatically generated.

    SHAPE
    Feature geometry. (Source: ESRI)
                      

    Coordinates defining the features.

    QUAD_NO
    Quadrangle Number - An ID number designated by the State of Connecticut, Department of Environmental Protection, Natural Resources Center in the 1980's to uniquely identify individual 7.5 minute 1:24,000-scale USGS topographic quadrangle maps. The Quadrangle Number value of each point feature identifies the USGS topographic quadrangle map that the orthophoto center point is located on. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Numeric value. Quadrangle maps published by the USGS that cover the Connecticut mainland and coastal area are assigned numeric values ranging from 1-116. Two quadrangle areas covering the waters of Connecticut in Long Island Sound are assigned numeric values 1213 and 1214.

    QUAD_SEC
    Quadrangle Section - There are 4 sections per 7.5 minute quadrangle, each one corresponding to a 3.75 minute quarter quadrangle area. The Quadrangle Section value of each point feature identifies the (NE, NW, SE, SW) section of the 7.5 minute 1:24,000-scale USGS topographic quadrangle map that the orthophoto center point is located on. (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    NE
    Northeast quarter quandrangle
    NW
    Northwest quarter quandrangle
    SE
    Southeast quarter quandrangle
    SW
    Southwest quarter quandrangle

    QUADRANGLE
    Quadrangle Name - Name of the 7.5 minute 1:24,000-scale USGS topographic quadrangle map published by the USGS that the orthophoto center point is located on. (Source: US Geological Survey)
                      

    Text value

    ORTHOPHOTO_TILE
    Orthophoto tile name - Unique name assigned to each orthophoto tile, which is the basis for individual image files names such as 0400731161_2.tif and 0400731161_2.sid for data in TIF and SID format, respectively. The first 9 digits (e.g. 040073116) identify the USGS 7.5 minute quadrangle map the orthophoto is located on. These first 9 digits are a concatenation of latitude, longitude, and quadrangle numbers. Digits 1 to 3 and 4 to 6 (e.g. 040073) correspond to latitude and longitude values for the quadrangle. Digits 7 to 9 (e.g. 116) represent the quadrangle number. Appended to the first 9 digits is a tenth digit, ranging from 1 to 4, that identifies the 3.75-minute quarter quadrangle area the orthophoto is located on. Appended these first 10 digits is a second sequence number, ranging from 1 to 9 (_1, _2, _3… _9), that identifies the tile section for the orthophoto image (e.g. 0400731161_2). There are 9 possible tile sections per 3.75-minute quarter quadrangle area. (Source: State of Connecticut, Department of Transportation)
                      

    0400731161_2, 0410710281_1, 0410710281_2, etc.

    STATE_COD
    State Code (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    CT
    State of Connecticut
    MA
    Commonwealth of Massachusetts
    NY
    State of New York
    RI
    State of Rhode Island

    TOWN_NO
    Town Number - ID number for the Connecticut Town (municipality), based on the Town Codes issued by the State of Connecticut, Office of the State Controller, which range from 1 to 169. (Source: State of Connecticut, Department of Transportation)
                      

    Numeric value ranging from 1 to 169 for tiles in Connecticut towns and 0 (zero) for tiles located in NY, MA, and RI.

    TOWN
    Town Name - Text values that correspond to numeric TOWN_NO attribute values. TOWN is the English language equivalent of (decodes) the TOWN_NO field. (Source: State of Connecticut, Department of Transportation)
                      

    Text value (town name).

    TOWN_NAME
    Town Name - Text values that corresponds to numeric TOWN_NO attribute values. TOWN_NAME is the English language equivalent of (decodes) the TOWN_NO field. Also includes names of Towns for polgygon features from Massachusetts, New York, Rhode Island where TOWN_NO = 0 and LAND_CLASS = "Land". (Source: State of Connecticut, Department of Environmental Protection)
                      

    Text value

    LAND_CLASS
    Land Class - Distinguishes land from water. This dataset includes a large water polygon feature that may impact polygon drawing performance. To improve drawing performance, exclude all water features by using the following expression in a layer definition query: LAND_CLASS = "Land" (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    Land
    Land Feature - Mainland or island
    Water
    Water Feature - Marine and selected large fresh waterbody

    SHAPE.area
    SHAPE.len
    Entity and attribute overview:
    Information encoded about each orthophoto-town polygon feature includes the name of the corresponding orthophoto image (ORTHOPHOTO_TILE) and identification of the quadrangle number (QUAD_NO), quadrangle name (QUADRANGLE), quadrangle section (QUAD_SEC), town number (TOWN_NO), and town name (TOWN) the orthophoto is located on.
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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?

    Aero-Metric, Inc. of Sheboygan Wisconsin was contracted by the State of Connecticut to provide the 2004 Statewide Aerial Survey of Connecticut. Contract deliverables include digital orthohotos, two sets of non-rectified prints for stereoscopic viewing, photo indexes, and LIDAR data. The scale of the accuracy of imagery, data and products meets horizontal National Map Accuracy Standards (NMAS) for 200-scale mapping. Photography is black and white and flown under clear sky conditions when deciduous trees and shrubs are in leafless condition ("leaves off") and the ground is free from ice, snow, cloud shaddows, and floodwaters. The Spring of 2004 was particulary wet, making it extremely difficult to arrive at conditions ideal for conducting a statewide aerial survey. Consequently, portions from 2000, 2005 and 2006 aerial surveys were used for orthophotographic production where there was unacceptable Spring 2004 orthophotography. All 2004 Statewide Aerial Survey imagery and data products defined under State of Connecticut contract award number RFP-990-A-14-0518-C (dated Feb 22, 2000), including contract award supplement #1 (dated Feb 28, 2002), contract award supplement #2 (dated Nov 4, 2004), contract award supplement #3 (dated Nov 26, 2004) and contract award supplement #4 (dated May 13, 2005).

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

    Howie Sternberg
    State of Connecticut, Department of Environmental Protection
    79 Elm Street
    Hartford, Connecticut 06106-5127
    USA

    860-424-3540 (voice)
    860-424-4058 (FAX)
    dep.gisdata@ct.gov
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time
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Why was the data set created?

These data serve as a town index to the set of 2004 orthophoto image tiles for Connecticut. Use it to determine the names of orthophoto image files that cover one or more town. Includes all Connecticut 2004 orthophoto tiles, including the few that are completely located outside the State of Connecticut along the state boundary. Polygon features representing portions of tiles located outside of Connecticut are encoded with Town Number values of 0 (zero).

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How was the data set created?

  1. Where did the data come from?

    Source 1 - Ortho_2004_Index_Tile (source 1 of 3)

    State of Connecticut, Department of Environmental Protection (data editor and publisher), State of Connecticut, Department of Transportation (data publisher), 2006, Connecticut 2004 Orthophoto Tile Index: State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    Type of source media: disc
    Source scale denominator: unknown
    Source contribution:
    These data serve as a polygon index to the set of 2004 orthophoto image tiles for Connecticut.

    Source 2 - Northeast_Master_Poly (source 2 of 3)

    State of Connecticut, Department of Environmental Protection (data compiler, editor and publisher), 2006, Northeastern United States Political Boundary Master: State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    Northeast_Master_Poly is a 1:24,000-scale, polygon and line feature-based layer that includes state, county, town (municipal), and some village boundary features for the States of Connecticut, Massachusetts, Maine, New Hampshire, New Jersey, New York, Rhode Island, and Vermont. Line features include state, county, town (municipal), and village  boundaries (primarily for New York). Polygon features are intended to depict the geographic areas for individual towns (municipalities) so that they can be aggregated up and combined to form county and state polygon features in derived data sets. Data is in ArcInfo coverage format in the Connecticut State Plane Coordinate System of 1983 (NAD 83). Map units are in feet. This information does not depict official state, county and town boundaries established by the respective state and municipal governments.

    Source 3 - Ortho_2004_Index_Tile_Town (source 3 of 3)

    State of Connecticut, Department of Environmental Protection (data editor and publisher), State of Connecticut, Department of Transportation (data publisher), 2006, Connecticut 2004 Orthophoto Tile Index by Town: State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    Type of source media: disc
    Source scale denominator: unknown
    Source contribution:
    These data serve as town index to the set of 2004 orthophoto image tiles for Connecticut.

  2. What changes have been made?

    Date: 2006 (change 1 of 1)
    Connecticut 2004 orthophoto index polygon features (source 1) were combined (unioned) with the Northeastern United States Political Boundary Master polygon features (source 2). The resulting polygon feature class was further simplified by first selecting all features in Connecticut (STATE_COD = "CT) and then dissolving (merging) adjacent polygon features with the same state, landclass, orthophoto tile and town designations. This process resulted in the creation of a smaller number of larger polygon features that described the orthophoto-town combination in a polygon feature class named Ortho_2004_Index_By_Town (source 3).

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

    860-424-3540 (voice)
    860-424-4058 (FAX)

    Data sources used in this process:
    • Source 1 - Ortho_2004_Index_Tile
    • Source 2 - Northeast_Master_Poly

    Data sources produced in this process:
    • Source 3 - Ortho_2004_Index_Tile_Town

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

  1. How well have the observations been checked?

    All attributes have valid values. Values are within defined domains. No rigid attribute accuracy tests were conducted other than visual inspection of the geoprocessing results.

  2. How accurate are the geographic locations?

    The horizontal positional accuracy of this data is unknown.

  3. How accurate are the heights or depths?

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

    The completeness of the data reflects the feature content of the primary data sources, which includes the original photo index for the 2004 orthophotos in CAD format from the State of Connecticut, Department of Transportation and a 1:24,000-scale data layer of Connecticut towns used to determine which towns the orthophoto tiles are located in.

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

    Polygon features conform to the following topological rules. Polygons are single part. Polygons overlap along the edges where orthophoto tiles overlap. The overlap between adjacent photos is approximately 350 to 450 feet. Establishment of logical consistency was performed by the State of Connecticut, Department of Environmental Protection using ESRI ArcGIS software to derive these polygon features from a union of two polygon data sources. No automated procedures or tests were performed to guarantee desired topology other than visual inspection.

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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. No restrictions or legal prerequisites for accessing the data. The data is in the public domain and may be redistributed.
Use constraints:
None. No restrictions or legal prerequisites for using the data after access is granted. The data is suitable for use at appropriate scale. When printing this data on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut, Departments of Environmental Protection and Transportation as the source for this information. For example, include the following data source description when printing this layer on a map: Photo Index - From the Connecticut 2004 Orthophoto Tile Index by Town layer, published by CT DEP and CT DOT.

Distributor 1 of 1

  1. Who distributes the data set?

    State of Connecticut, Department of Enviromental Protection
    79 Elm Street
    Hartford, Connecticut 06106-5127
    USA

    860-424-3540 (voice)
    860-424-4058 (FAX)
    dep.gisdata@ct.gov
    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?

    Connecticut 2004 Orthophoto Tile Index by Town

  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 the 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:
      in format Shapefile, Feature Class (version ArcGIS)
      Network links:http://www.ct.gov/deep

    • Cost to order the data: An online 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: 20111208

Metadata author:
Howie Sternberg
State of Connecticut, Department of Environmental Protection
79 Elm Street
Hartford, Connecticut 06106-5127
USA

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

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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