King County Image/Raster User Tiling Index - idxptrmbr

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Frequently-anticipated questions:


What does this data set describe?

    Title: King County Image/Raster User Tiling Index - idxptrmbr
    Abstract:
    A spatial tiling index designed for storage of file-based image and other raster (i.e., LiDAR elevation, landcover) data sets. An irregular grid of overlapping polygons, each enclosing its respective Public Land Survey System (PLSS) township in an orthogonal polygon minimally encompassing all portions of that township, i.e., minimum bounding rectangle. The amount of overlap between adjacent tiles varies depending on the geometry of the underlying township.

    Currently extended to include all townships within or partially within King County as well as those townships in the southwestern portion of Snohomish County included within King County's ESA/SAO project area.

    The name of the spatial index is derived from the acronym (I)n(D)e(X) (P)olygons for (T)ownship-(R)ange, (M)inimum (B)ounding (R)ectangle, or idxptrmbr.

    Tile label is the t(township number)r(range number)as in t24r02. The meridian zone identifiers, N for townships and E for range is inferred as this index is intended as a local index for ease of use by the majority of users of GIS data. Lowercase identifiers are used for consistency between Unix and Windows OS storage.

    This index or tile level is the primary user-access level for most LiDAR elevation, orthoimagery and high-resolution raster landcover data. However, not all image and raster data is stored at the tiling level if a given data's resolution does not justify storing the data as multiple tiles.

    Supplemental_Information:
    This spatial index is one of three index or tiling levels used to store King County image and raster data. The index level lower than this is the idxp7500 index. The index level immediately higher than this is idxpzone. 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 User Tiling Index - idxptrmbr: 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 beyond referencing the extent of the underlying township.
      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)

    mbr_id
    Unique integer identifier for each tile composed the township number cocantenated with the range number, i.e. the identifier for township 22, range 12 would be 2212, the identifier for township 22, range 03 would be 2203. (Source: User-defined)

    Unique integer comprised of two-digit township integer cocantenated with two-digit (left-padded with zero where necessary) range number.

    mbr_abb
    Unique alphanumeric identifier for each cell comprised of township number prefaced with 'T' cocantenated with range number (left-padded with zero, where necessary) prefaced with a 'R'. (Source: User-defined)

    Alphanumeric code

    mbr_abblc
    Same alphanumeric township-range identifier found in mbr_abb item but with lowercase t and r, indicating township and range, respectively. (Source: User-defined)

    Unique alphanumeric code

    mbr_twn
    Two-character alpha code for township number. (Source: User-defined)

    Alpha expression of township number

    mbr_range
    Two-character alpha code for township number. (Source: User-defined)

    Alpha expression of Range number. Left-padded with zero where necessary.

    xmin
    Minimum State Plane easting value for tile bound. (Source: User-defined)

    Seven digit integer

    ymin
    Minimum State Plane northing value for tile bound. (Source: User-defined)

    Six-digit integer

    xmax
    Maximum State Plane easting value for tile bound. (Source: user-defined)

    Seven-digit integer

    ymax
    Maximum State Plane northing value for tile bound. (Source: User-defined)

    Six-digit integer

    Entity_and_Attribute_Overview:
    All tiles are identified with a several attributes that indicate the tile-id, its bounding coordinates and the township-range represented. As the shapefile serves primarily as a spatial index,the mbr_abb and mbr_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 the primary User Access level for image/raster datasets. It provides multiple file-based data sets to be accessed at full or near full resolution in a common, consistent tile and naming scheme.

The index also serves as a useful central reference scheme for identification of real-world locations as it references the commonly used township-range grid of the PLSS.

As each cell is defined with orthogonal edges relative the Washington State Plane coordinate system, and is defined by easting and northing bounds rounded to the nearest 100 foot, it accomodates most common pixel resolutions of multiple Ground Sample Distance 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 in a compressed format or at reduced resolution.

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

    Date: (process 1 of 4)
    Heads up digitizing was used to create minimum-bounding rectangles around each township in the project area. This portion included the subjective interpretation of the amount of buffer to include in each tile. This was performed in a CAD-based software package called VROne

    Date: (process 2 of 4)
    The minimum and maximum bounds were captured in a Microsoft Excel spreadsheet where the bounds were rounded to the next highest 100 foot easting and northing increment.

    Date: Feb-2003 (process 3 of 4)
    The spreadsheet was converted to a text file which was used in an ArcInfo AML to create individual shapefile polygons for each township tile. The shapefiles were merged in ArcView to a composite shapefile. Final attributes, including min and max bounds and identifiers were appended from a text file converted to a dbf.

    Date: (process 4 of 4)
    Some of the township tile bounds along the edges of the King County were not described to the true extent of the township but rather to the extent of the data available from the data projects. To standardize the extents of all tiles and to ensure that subsequent tiles could be appended, any partial townships were regenerated. The Excel spreadsheet was updated to reflect the new bounds, new tiles generated and the composite index shapefile was updated.

  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 unique and reference the underlying township/range that encompasses.

  2. How accurate are the geographic locations?

    The bounds of each cell were generated from State Plane easting and northing coordinate values defined by a minimum bounding rectangle interpretation of the township extent. Overlap with adjacent tiles was provided to ensure sufficient data buffers. The interpreted bounds were rounded up the next nearest 100 foot easting and northing value.

  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. Those tiles at the edge of the current data project area are defined to their full township extent to allow appending subsequent townships if necessary.

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

    All cells have a label attribute. The half-townships in eastern King County are included in the tile of full township of the same name, i.e., t24.5sr11e is included in the t24r11 tile.


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 User spatial index, idxtrmbr.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