King County Image/Raster Zone tiling index - idxpzone

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Frequently-anticipated questions:

What does this data set describe?

    Title: King County Image/Raster Zone tiling index - idxpzone
    A spatial tiling index designed for storage of file-based image and other raster (LiDAR elevation, landcover) data sets at high compression ratio or at a lower resolution appropriate for the dataset at this tile level. A polygon index that divides King County and adjacent project areas into roughly 4 equivalent 'quadrant'areas. This index is an aggregate of cells (tiles) from the idxp7500 index level.

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

    Each zone overlaps adjacent zones by 15000 feet, the dimension of two 7500 ft tile cells.

    Tile identifier is the map quadrant each tile occupies, NE,NW,SW and SE, with expanded zone_names: northeast, northwest, southwest and southeast, respectively. When used as part of a file name the tile identifier is prefaced with a 'z' indicating that its extent is derived from the idxpzone scheme, i.e, zne, znw, zsw, zse.

    This spatial index is one of three index or tiling levels used to store King County image and raster data. This is the highest level index. Data sets are also stored at the KeyRegion level in their entirety, but the KeyRegion is not considered an index level.

  1. How should this data set be cited?

    County, King, 200307, King County Image/Raster Zone tiling index - idxpzone: 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?

      The grid defined by this index is a regular grid that does not have any additional or indirect spatial reference, beyond the general correlation to the map quadrant indicated by the tile identifier.
      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
      SPCS_Zone_Identifier: Washington, North
      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)

    Single digit integer identifier for each zone. (Source: User-defined)

    1Northwest zone
    2Northeast zone
    3Southeast zone
    4Southwest zone

    Two-character alpha code (uppercase) abbreviation for each zone map position. (Source: User-defined)

    NWNorthwest zone
    NENortheast zone
    SESoutheast zone
    SWSoutheast zone

    Expanded name descriptor for zone map area, i.e., Southeast, Southwest, Northwest, Northeast (Source: User-defined)

    Unique alpha code phrase

    Each tile is identified with a integer zone_id, a two-character zone abbreviation, and a full zone location name. As the shapefile serves primarily as a spatial index,the attributes are needed to correctly reference and describe the location of the index 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

    206-263-4867 (voice)

Why was the data set created?

This index is primarily a index for accessing raster and image data for small-scale (i.e., regional) or broad area applications. Users may wish to access this index level of a dataset if their area of interest would require accessing multiple copies of the township-range tiles (idxptrmbr).

Data at this tile level is often stored at a lower resolution and/or higher compression ratio than the same data set stored at a lower tiling level, but provides the opportunity for users to choose the tile form of the data most appropriate for their needs.

As each cell is defined with orthogonal edges relative to its underlying idxp7500 tiles, it accomodates most common pixel resolutions of multiples sample distance (gsd) without partial pixel effects and without zero or NULL data 'splinters'.

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 smaller tile size. Alternatively, most data available at this level is also found at the primary user access tile level - idxptrmbr - based on the Public Land Survey System (PLSS) township-range grid.

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.

    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
    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 2)
    Separate subsets of the underlying idxp7500 layer was reselected based on their Zone attribute identifier. ArcInfo Dissolve command was used to dissolve on the zone identifier.

    Date: 2002 (process 2 of 2)
    The four separate coverages were converted to shapefiles and merged in ArcView. ArcView was used to edit the associated dbf file to add additional attributes.

  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 tile are sequential and unique, descriptive of the map quadrant they cover (relative to King County-ESA/SAO project area extent).

  2. How accurate are the geographic locations?

    The bounds of each tile were generated from State Plane easting and northing coordinate values defined from the 0,0 origin and are divisable by 7500 (i.e, extracted from idxp7500 index cells).

  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 tiles 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

    206-263-4523 (voice)

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

    Image/Raster data Zone spatial index, idxpzone.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?

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

206-263-4863 (voice)

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

Generated by mp version 2.7.33 on Sat Dec 18 22:12:58 2004