7500-FT Tiling Status for KC Raster Datasets

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Frequently anticipated questions:

What does this data set describe?

Title: 7500-FT Tiling Status for KC Raster Datasets
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.
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. Individual shapefiles for each of the cells in this index are available in gisimage/images/reference/indexes/idxp7500_shp as 'tileabb'_bnd.shp.
  1. How should this data set be cited?

    County, King, 20030701, 7500-FT Tiling Status for KC Raster Datasets: King County, King County, WA.

    Online Links:

    Other_Citation_Details: None

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -122.570272
    East_Bounding_Coordinate: -121.005504
    North_Bounding_Coordinate: 47.986791
    South_Bounding_Coordinate: 47.048751

  3. What does it look like?

    <http://www5.kingcounty.gov/sdc/DataImages/raststat_7500.jpg> (JPG)
    JPG File of layer overlain on base of WA counties or local cities

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

    Calendar_Date: 01-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.
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • GT-polygon composed of chains (0)

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

      The map projection used is NAD 1983 HARN StatePlane Washington North FIPS 4601 Feet.

      Projection parameters:
      Standard_Parallel: 47.5
      Standard_Parallel: 48.73333333333333
      Longitude_of_Central_Meridian: -120.8333333333333
      Latitude_of_Projection_Origin: 47.0
      False_Easting: 1640416.666666667
      False_Northing: 0.0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.0003280833333333334
      Ordinates (y-coordinates) are specified to the nearest 0.0003280833333333334
      Planar coordinates are specified in foot_us

      The horizontal datum used is D North American 1983 HARN.
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.

  7. How does the data set describe geographic features?

    Polygon attribute table (Source: ESRI)

    Feature Geometry (Source: ESRI)

    Coordinates defining the features

    Polygon area (Source: ESRI)

    Area of feature in square feet

    Polygon perimeter (Source: King County)

    Length of feature in feet

































    Internal feature number. (Source: ESRI)

    Range of values

    Sequential unique whole numbers that are automatically generated.

    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: King County)

    Unique alphanumeric code

    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?

    King County GIS Center
    Attn: Victor High
    Senior GIS Specialist
    201 S Jackson St, Suite 706
    Seattle, WA 98104

    206-263-4845 (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?

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

    Date: 01-Jan-2002 (process 1 of 4)
    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: 01-Jan-2003 (process 2 of 4)
    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. Process_Date: 012003

    Date: 01-Jun-2003 (process 3 of 4)
    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.

    Date: 01-Mar-2010 (process 4 of 4)
    Grid imported from shapefile to featureclass. Grid extended along northern edge in Snohomish County to accomodate expansion of new image acquisition projects.

  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
King County data are made available with the understanding that they shall be used exclusively by the obtainer or his/her authorized agents. Digital products may not be reproduced or redistributed in any form or by any means without the express written authorization of King County.

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

    KCGIS Center
    Attn: Cheryl Wilder
    Data Sales Coordinator
    201 S Jackson St, Suite 700
    Seattle, WA 98104

    206-263-5220 (voice)

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


  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: 20-Feb-2013
Metadata author:
King County GIS Center
Attn: Mike Leathers
GIS Data Coordinator
201 S Jackson St, Suite 706
Seattle, WA 98104

206-263-4867 (voice)

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

Generated by mp version 2.9.12 on Sat Apr 06 05:37:32 2019