King County Image/Raster Library Tile Status - raststat_7500.shp and raststat_trmbr.shp

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Frequently-anticipated questions:


What does this data set describe?

    Title:
    King County Image/Raster Library Tile Status - raststat_7500.shp and raststat_trmbr.shp
    Abstract:
    Spatial indexes which show the availability/non-availabilty of various raster and image data sets in the King County Spatial Data Warehouse (KCSDW) at two separate tiling levels.

    Two indexes are available - one for the lowest tiling level (smallest extent) based on the idxp7500 tiling index and one for the user tiling level (2nd tier) based on the idxptrmbr tiling index.

    Each of the tiling indexes themselves are described with their own metadata. This metadata describes derivatives of each of the indexes that are updated with the current status of individual tiles in the warehouse. A weekly script builds an attribute table based on the subdirectories in the master directories of the warehouse and the contents of each directory.

    Some image and raster data exists solely at the higher Zone and KeyRegion levels and is not stored at the idxp7500 or idxptrmbr tiling level. The status indexes will not indicate the availability of this data.

    Supplemental_Information: None

  1. How should this data set be cited?

    County, King, 200307, King County Image/Raster Library Tile Status - raststat_7500.shp and raststat_trmbr.shp: 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 the idxp7500 index is a regular grid that does not have any additional or indirect spatial reference. The grid defined by the idxptrmbr index references the underlying PLSS township-range grid.
      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 regarding the availability or non-availability of data tiles. (Source: Software assigned and user indexed)

    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. The details regarding these static attributes can be found in the metadata for the index itself.

    The other attributes in the shapefile dbf are dynamic, being generated from the current subdirectory list in the raster library. Some modification of the names is made to accomodate the naming limitations of the dbf format. The item name indicates the dataset that is stored in that library.

    The value for each item is either a 'Y' for Yes, the tile exists, or 'N', the tile does not exist.

    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?

These status indexes are useful for displaying or querying for the availability of various image and raster data sets in the King County Spatial Data Warehouse. These indexes show the tiles available at the first and second tiling levels. The third tiling level, idxpzone, and the top-level storage directory, KeyRegion, do not have status indexes. Users will need to search these library directories directly, but will find that most data available at the lower tiling levels has a lower resolution version at the Zone and KeyRegion. These status indexes are most useful for the two lowest tiling levels due to the large number of files at each level and because different data types are represented at each level.

Few of the raster data sets in the warehouse have coincident extents so these status indexes can be used to determine which data sets are available for a given area of interest.

The items in the status index attribute tables are dynamic, reflecting the current directory structure of the warehouse raster library. As new data is acquired or processed into a different format new directories are added. The items names are auto-generated from the directory names and are generally descriptive. However users should access data set metadata and other documentation in the KCGIS Spatial Data Catalog for additional information.

<http://www.metrokc.gov/gis/sdc/index.htm>

The status is designated as either Y for the data tile's presence or N for its absence. No other information regarding the data tile or the data set is provided. Users are directed to the data set metadata for this information.

The presence of a tile does not necessarily indicate that the tile has actual useable data to its full extent, as tiles are created where any data exists within that extent. For more information regarding the actual extent of a given dataset, please see the allextents.shp shapefile in the KCGISDW raster library.


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 Spatial Data Warehouse, Raster tiling indexes: 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 2)
    A weekly script, raststat.aml, is executed. This script searches the idxp7500 and idxptrmbr master directories of the plibrary3 raster library of the KCSDW. A info table is created for each path, populated with all possible tiles in each spatial index that complements each directory. Each info table is appended with item names reflecting the current subdirectories in each in master directory. Each subdirectory is searched and a data list is created. This data list is used to update each info table with either a 'Y' indicating that a tile for that geographic index location exists or a 'N' if no data tile exists for that geographic index location.

    Date: (process 2 of 2)
    The output info files are inspected for integrity and then appended to a copy of each of the spatial index shapefiles, idxp7500.shp and idxptrmbr.shp. The updated shapefile is then copied to the status directory in the raster library as raststat_7500.shp and raststat_trmbr.shp.

  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?

    Availability codes reflect the current status of tiles in the King County Spatial Data Warehouse. The update script does not account for cases where a given geographic tile may be represented twice in the same data type directory due to multiple sources. This does not occur frequently. The script also does not account for the presence of multiple format types for the same geographic tile and dataset. For example, an orthophotography image may exist as jp2 and tif in the same directory. The status index only indicates that the tile exists, and does not provide information about the number of instances or their nature.

  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 records have either a 'Y' or 'N' representing tile availability for each item name which corresponds to a data directory name.


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 tile status indexes, raststat_7500.shp and raststat_trmbr.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