King County Image/Raster base tiling index - idxp7500

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Frequently-anticipated questions:


What does this data set describe?

    Title: King County Image/Raster base tiling index - idxp7500
    Abstract:
    A spatial tiling index designed for storage of file-based image and other raster (i.e., LiDAR elevation, landcover) data sets. A regular grid with origin at 0,0 of the Washington North State Plane Coordinate System, with grid cells defined by orthogonal bounds 7500 feet long in easting and in northing. Only those cells currently involved in one of several image/raster data projects for King County and southwestern Snohomish County are labelled, though the labeling scheme can be extended.

    The name of the spatial index is derived from the acronym (I)n(D)e(X) (P)olygons at the (7500) foot tile level, or idxp7500.

    Cell label is a row-id cocantenated with a column-id generating a four-character identifier that uniquely identifies every cell. The row portion of the identifier is a two-character alpha code of the format aa, ab, ac.... ba, bb, etc. and the column portion is a two-digit integer value such as 01, 02, 03.... 11,12,13, etc. A composite cell identifier would be then, for example, aa01, aa02, .....ba11,ba12, etc.

    Not all image and raster data is stored at the tiling level represented by this index. Data is stored at this level if full-resolution, uncompressed data would generate larger than manageable file sizes at a larger tile size.

    Supplemental_Information:
    This spatial index is one of three index or tiling levels used to store King County image and raster data. Each higher index level is designed to build upon the lower levels, with the same data often stored at more than one level (though at different resolutions) to meet a range of business and software requirements.

  1. How should this data set be cited?

    County, King, 200307, King County Image/Raster base tiling index - idxp7500: King County, King County, WA.

    Online Links:

    • None

    Other_Citation_Details: None

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -121.500000
    East_Bounding_Coordinate: -121.100000
    North_Bounding_Coordinate: +47.800000
    South_Bounding_Coordinate: +47.100000

  3. What does it look like?

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

    Beginning_Date: Jan-2003
    Ending_Date: Jul-2003
    Currentness_Reference: Publication date

  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 grid defined by this index is a regular grid that does not have any additional or indirect spatial reference.
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • Ring composed of arcs

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

      Grid_Coordinate_System_Name: State Plane Coordinate System 1983
      State_Plane_Coordinate_System:
      SPCS_Zone_Identifier: Washington, North
      Lambert_Conformal_Conic:
      Standard_Parallel: 47.500000
      Standard_Parallel: 48.733333
      Longitude_of_Central_Meridian: -120.833333
      Latitude_of_Projection_Origin: 47.000000
      False_Easting: 1640416.666500
      False_Northing: 0.000000

      Planar coordinates are encoded using Row and column
      Abscissae (x-coordinates) are specified to the nearest 1
      Ordinates (y-coordinates) are specified to the nearest 1
      Planar coordinates are specified in Survey feet

      The horizontal datum used is North American Datum of 1983, 1991 Adjustment (HPGN).
      The ellipsoid used is GRS 80.
      The semi-major axis of the ellipsoid used is 20925604.4720406.
      The flattening of the ellipsoid used is 1/298.26.

  7. How does the data set describe geographic features?

    Shapefile dbf attribute file
    Index cell identifier and descriptive attributes (Source: Software assigned and user indexed)

    tile_id
    Five-digit unique integer identifier for each cell (Source: User-defined)

    Unique integer

    tile_abb
    Unique alphanumeric identifier for each cell comprised of two-character alpha code defining in which spatial column the cell exists cocantenated with a two-digit numeric code defining in which spatial row the cell exists. Alpha portion is uppercase. (Source: User-defined)

    Alpha code

    tile_abblc
    Primary 'colloquial' identifier for each cell identical in value to the tile_abb, but where the alpha portion of the code is lowercase. Unique alphanumeric identifier comprised of two-character alpha code defining in which spatial column the cell exists cocantenated with a two-digit numeric code defining in which spatial row the cell exists. (Source: User-defined)

    Unique alphanumeric code

    col_abb
    Unique alpha identifier for each column, in uppercase. (Source: User-defined)

    Alpha codes beginning with AA and sequencing as AB, AC... AZ, then reinitializing as BA, BB, ... out to the current limit of the defined cells.

    col_abblc
    Unique alpha identifier of each column in lowercase. (Source: User-defined)

    Alpha codes beginning with aa and sequencing as ab, ac... az, then reinitializing as ba, bb, ... out to the current limit of the defined cells.

    col_id
    Three-digit numeric code uniquely identifying each column (Source: User-defined)

    Sequence initiallized at 101 and sequencing as value + 1.

    row_id
    Unique integer identifier for each row (Source: User-defined)

    One or two-digit integer identifier uniquely identifying each row. When cocantenated with column_abb to create tile_abb, the integer is left padded with a zero when necessary to ensure that all tile_abb always contain four characters.

    area_sqft
    Restating of system-generated area value to provide area value in square feet if shapefile is projected to different system. (Source: user-defined)

    Range of values
    Minimum:56250000
    Maximum:56250000

    area_sqkm
    Area of each cell in square kilometer (Source: User-defined)

    Range of values
    Minimum:5.225
    Maximum:5.225

    area_sqmi
    Area of each cell in square miles. (Source: User-defined)

    Range of values
    Minimum:2.017
    Maximum:2.017

    perim_ft
    Restating of system-generated area value to provide area value in square feet if shapefile is projected to different system. (Source: User-defined)

    Range of values
    Minimum:30000
    Maximum:30000

    perim_m
    Perimiter of each cell in meters (Source: User-defined)

    Range of values
    Minimum:9144
    Maximum:9144

    xmin
    Minimum State Plane Washington North Zone Easting (Source: User-defined)

    Integer

    ymin
    Minimum State Plane Washington North Zone Northing (Source: User-defined)

    Integer

    xmax
    Maximun State Plane Washington North Zone Easting (Source: User-defined)

    Integer

    ymax
    Maximun State Plane Washington North Zone Northing (Source: User-defined)

    Integer

    zonenw
    Defines whether cell belongs to Northwest Zone polygon of idxpzone index (Source: User-defined)

    ValueDefinition
    NWCell belongs to Northwest Zone
    NCell does not belong to Zone

    zonene
    Defines whether cell belongs to Northeast Zone polygon of idxpzone index (Source: User-defined)

    ValueDefinition
    NECell belongs to Northeast Zone
    NCell does not belong to Zone

    zonene
    Defines whether cell belongs to Southeast Zone polygon of idxpzone index (Source: User-defined)

    ValueDefinition
    SECell belongs to Southeast Zone
    NCell does not belong to Zone

    zonesw
    Defines whether cell belongs to Southwest Zone polygon of idxpzone index (Source: User-defined)

    ValueDefinition
    SWCell belongs to Southwest Zone
    NCell does not belong to Zone

    Entity_and_Attribute_Overview:
    All cells are identified with a several attributes that represent unique row, column and cell identifiers as well as other parameters. As the shapefile serves primarily as a spatial index, the tile_abb and tile_abblc are the primary attributes needed to correctly reference and describe the location of the cell tile.
    Entity_and_Attribute_Detail_Citation: None


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?

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

    Michael Leathers
    King County Geographic Information Center,
    GIS Data Coordinator
    201 S Jackson St, Suite 706
    Seattle, WA 98104
    USA

    206-263-4867 (voice)


Why was the data set created?

This index is primarily a data processing, data storage level index which allows all raster and image data stored at this level to be maintained in a common, consistent tile and naming scheme. The index also serves as a useful central reference scheme for identification of real-world locations.

This index level is useful for users of LiDAR-derived elevation data stored as TINS because TIN format data, as well as ASCII format data, are stored only at this tiling level. Imagery in native uncompressed format will also be stored only at this level.

As each cell is defined with orthogonal edges relative the Washington State Plane coordinate system, it accomodates most common pixel resolutions of multiple ground sample distance (gsd) without partial pixel effects and without zero or NULL data 'splinters'.


How was the data set created?

  1. From what previous works were the data drawn?

    ESA/SAO (source 1 of 1)
    County, King, 2003, King County ESA/SAO Data Acquisition project: King County, King County, WA.

    Other_Citation_Details:
    This index was developed jointly between the King County Dept of Transportation Roads Maintenance Dept and the King County GIS Center
    Type_of_Source_Media: Not Applicable
    Source_Contribution:
    A common data storage mechanism for file-based image/raster data at highest (full) resolution.

  2. How were the data generated, processed, and modified?

    Date: (process 1 of 3)
    ArcInfo GENERATE command with FISHNET option was used to create the polygon coverage of individual cells. The coverage was converted to a shapefile. An integer row-id and integer column-id were updated for the PAT. The values from each of these items was cocatenated to produce a unique integer identifier for each cell.

    Date: 2002 (process 2 of 3)
    Microsoft Excel was used to create a master attribute spreadsheet with all other cell attributes tied to the unique integer id of each cell. The data from the spreadsheet was exported to text format and joined to the shapefile dbf in ArcView. The resulting updated shapefile was reexported to a final shapefile.

    Date: Jun-2003 (process 3 of 3)
    To accomodate generation of the Zone level tiling index, additional attributes were added to the index shapefile dbf to indicate of which zone each cell is a member.

  3. What similar or related data should the user be aware of?


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

  1. How well have the observations been checked?

    Identifiers for each cell are sequential and unique.

  2. How accurate are the geographic locations?

    The bounds of each cell were generated from State Plane easting and northing coordinate values defined from the 0,0 origin and at even 7500 increments.

  3. How accurate are the heights or depths?

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

    The index currently covers the King County and southwestern Snohomish County areas currently involved in several related image/raster data acquisition projects. The extent has been buffered to encompass some adjoining areas.

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

    All cells have a label attribute


How can someone get a copy of the data set?

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

Access_Constraints: None
Use_Constraints: None

  1. Who distributes the data set? (Distributor 1 of 1)

    Dennis Higgins
    King County GIS Center, Client Services,
    Manager, Client Services Division
    201 S Jackson St, Suite 706
    Seattle, WA 98104
    USA

    206-263-4523 (voice)

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

    Image/Raster data base spatial index, idxp7500.shp

  3. What legal disclaimers am I supposed to read?

    King County disclaims any warranty of use of any digital product or data beyond that for which it was designed.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 15-Jul-2003

Metadata author:
Michael Leathers
King County GIS Center,
GIS Data Coordinator
201 S Jackson St, Suite 706
Seattle, WA 98104
USA

206-263-4863 (voice)
mike.leathers@metrokc.gov

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


Generated by mp version 2.7.33 on Sat Dec 18 22:12:59 2004