2009 eCityGov Alliance Natural Color Orthoimagery

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Frequently-anticipated questions:

What does this data set describe?

Title: 2009 eCityGov Alliance Natural Color Orthoimagery
Year 2009 (early Spring), leaf-off, natural color orthoimagery acquired by the eCityGov Alliance for partnering cities - Mercer Island, Bellevue, Kirkland, Bothell and Shoreline. Vendor was MJ Harden. Pixel resolution is 0.25 foot.
Supplemental_Information: None
  1. How should this data set be cited?

    Alliance, eCityGov, 201003, 2009 eCityGov Alliance Natural Color Orthoimagery: Aerials Express, King County; WA.

    Online Links:

    • None

    Other_Citation_Details: None

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -122.44
    East_Bounding_Coordinate: -122.23
    North_Bounding_Coordinate: 47.74
    South_Bounding_Coordinate: 47.49

  3. What does it look like?

    <http://www5.kingcounty.gov/sdc/raster/ortho/images/Ortho2009eCityGovNATExtent.jpg> (JPEG)
    Extent of project area
    <http://www5.kingcounty.gov/sdc/raster/ortho/images/Ortho2009eCityGovNATSample.jpg> (JPEG)
    Sample of imagery

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

    Beginning_Date: 2009
    Ending_Date: 2009
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: Raster image data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Raster data set. It contains the following raster data types:

      • Dimensions, type Pixel

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

      Grid_Coordinate_System_Name: State Plane Coordinate System
      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 Feet

      The horizontal datum used is North American Datum of 1983; 1991 correction.
      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?

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?

    Mike Leathers
    GIS Data Coordinator
    201 S Jackson St
    Seattle, WA 98104

    206-263-4867 (voice)

Why was the data set created?

High-resolution, high-accuracy data for multiple business purposes.

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: Mar-2010 (process 1 of 4)
    Data acquired from eCityGov Alliance in March 2010 via portable harddrive and DVD. Data was copied to workspace. Compressed MrSid versions (20x) were created for each tile for preliminary QA, horizontal accuracy analysis, and completion of extent shapefile. No spatial index was delivered with the data. A python routine was created to create a photo centroid layer. This point layer was buffered by 1600 feet to create a polygon footprint index. The photo center to edge is only 1500 feet, but the buffer was created larger than the image because the delivered tiles extent coincides in places with the King County 7500 grid. The overlap ensures that tile selection during subsequent processing does not miss an edge tile.

    Date: Feb-2010 (process 2 of 4)
    MrSid (v7) was used to create Generation 3 SID (lossless) mosaics in the King County 7500-ft tiling scheme. Another similar routine was used to create Generation 3 mosaics (15x compression) in the King County Township-Range tiling scheme.

    (process 3 of 4)
    Redefined Projection for all sids to be compliant with King County standard.

    Date: 15-May-2010 (process 4 of 4)
    The database size was too large to mosaic as a single sid even at high compression. The data was resampled to 6 inch and a mosaic was also created for the affected Northwest Zone tile (35x compression) . A key region mosaic was created at 50x compression. Even though the key region mosaic covers that same area as the zone mosaic, it provides the complete dataset in a smaller file footprint.

  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?

    There are no attributes associated with these raster data formats.

  2. How accurate are the geographic locations?

    An analysis of 78 control points (70 known ground control and 9 'blind') showed a RMS (root mean square) accuracy of 0.39 feet in the X direction and 0.22 feet in the Y direction.
    The full analysis can be viewed at: <http://www5.kingcounty.gov/sdc/raster/ortho/photo_control_master_09n025_RMSError.xls>

  3. How accurate are the heights or depths?

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

    Not all 7500 foot tiles and Township-Range tiles along the edges of the project area are complete image tiles.

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


How can someone get a copy of the data set?

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

As a licensee, King County is permitted to copy, analyze, print, and otherwise use the data at the licensee's sole discretion. Any use of the data in the production of printed maps or other graphic products shall credit the Licensor (eCityGov Alliance) as the source agency and copyright holder of the data in such products. The data may be distributed to all authorized users within the licensee's organization, but no distribution of the data is permitted to staff and/or programs of external organizations, except by prior agreement of Licensor.
King County digital data may not be reproduced or redistributed in any form or by any means without the express written authorization of the King County Department of Natural Resources and Parks/KCGIS-Center.

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

    Mike Leathers
    KC GIS Center
    GIS Data Coordinator
    201 S Jackson St
    Seattle, WA 98104

    206-263-4867 (voice)

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

    txxryy_09n025.sid Also as 7500 tiles in TIF format, and zone and keyregion mosaics

  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-Mar-2010
Metadata author:
Mike Leathers
GIS Data Coordinator
201 S Jackson St
Seattle, WA 98104

206-263-4867 (voice)

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

Generated by mp version 2.9.6 on Wed Apr 10 12:32:07 2013