NatcolorXX.tif-DAIS Natural Color 8-bit Aerial Photography

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Frequently-anticipated questions:

What does this data set describe?

Title: NatcolorXX.tif-DAIS Natural Color 8-bit Aerial Photography
Low elevation, high resolution (i.e., small ground sample distance (GSD)) aerial photography collected in September, 2000 for Vashon and Maury Islands, portions of King County that reside in Puget Sound, approximately 5 miles west of the city of Seattle. The data has a pixel size of 0.5 meters and is displayed in natural color for visual analysis.
The images were converted from original 4-band, near infrared, 16-bit format to 3-band, natural color, 8-bit format. The reduction in dynamic range of the data from 16 to 8 bit allows the imagery to be viewed in most image viewing and GIS software. This is a true natural color image as the images were created by dropping the near infrared band and combining the remaining blue, red and green bands. The images can be accessed as individual TIFFs tile by tile, as a pseudo-mosaic by using the associated image catalog dbase file (dais_nat.dbf), where supported, or a single MrSid mosaic (dais_nat.sid), where supported.
  1. How should this data set be cited?

    County, King, 20010126, NatcolorXX.tif-DAIS Natural Color 8-bit Aerial Photography: King County, King County,WA.

    Online Links:

    This dataset was collected as part of a larger multispectral image acquisition effort contracted through Pacific Meridian Corporation, a subsidiary of Space Imaging, Inc. The DAIS (Digital Airborne Imagery System) component is one of Space Imaging's Caterra products. Licensing and use restrictions are part of this acquisition contract. Please contact the Point of Contact for licensing restrictions.
    This is part of the following larger work.

    County, King, 2000, ESA/SAO Multispectral Image Acquisition: King County, King County, WA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -122.5384
    East_Bounding_Coordinate: -122.3411
    North_Bounding_Coordinate: 47.5334
    South_Bounding_Coordinate: 47.3111

  3. What does it look like?

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

    Beginning_Date: 23-Sep-2000
    Ending_Date: 23-Sep-2000
    Currentness_Reference: Acquisition date

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

    Geospatial_Data_Presentation_Form: Image digital 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 7091 (representative) x 4898 (representative), 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
      Planar coordinates are specified in Feet

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

    The imagery are stored as raster TIFF format files. They have no attribute tables. Information regarding the collection parameters for the imagery may be found in the metadata for the Multispectral Image version of the data as well as in the metadata for the spatial index for this dataset - idxpdais.shp

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 Department of Natural Resources
    c/o Michael Leathers
    GIS Database Administrator
    201 S. Jackson St, Suite 700
    Seattle, Washington 98104

    206-296-3775 (voice)
    206-296-3749 (FAX)

    Hours_of_Service: 8:00-4:30 PST M-F

Why was the data set created?

This image dataset comprises 25 individual image tiles stored in TIFF format that can be displayed as a single seamless mosaic. The raw imagery was converted to natural color version.The imagery, within the horizontal accuracy and resolution limitations, serves as digital backdrop imagery for GIS analysis and cartographic display. In particular, the absolute and relative horizontal accuracy should be carefully considered when either determining coordinate positions or when applying the data relative to other spatial datasets.

How was the data set created?

  1. From what previous works were the data drawn?

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

  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?

  2. How accurate are the geographic locations?

    The raw images were georectified by the vendor using available 10 m DEM supplemented by limited GPS ground control. After delivery of the tiled images, in-house horizontal accuracy analysis indicated that the data met or exceeded the contract specification for NMAS 1:10000 (CE90 of 4 m = 13.1 feet). The number of known ground control for confirmation was very small (9) and three of the locations were not discernable on the imagery. For the remaining six discernable points the horizontal offset between the imagery and the known control point ranges from 1 to 2 meters. Initial review indicates that the data exhibits this level of accuracy relatively evenly over the area of interest without significant skewing. See <>

  3. How accurate are the heights or depths?

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

  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?

Access_Constraints: Online access is restricted to King County GIS users.
King County digital data may not be reproduced or redistributed in any form or by any means without the express written authorization of the the King County Department of Information and Administrative Services. Specific contraints apply per the licensing agreement with Space Imaging.

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

    King County
    c/o Cheryl Wilder
    700 5th Ave., Suite 2300
    Seattle,, Washington 98104

    206-263-5220 (voice)

    Hours_of_Service: 8:00-5:00 PST M-F
  2. What's the catalog number I need to order this data set?

    natcolorXX.tif where XX references a tile_id linked to a single polygon location in idxpdais.shp index scheme

  3. What legal disclaimers am I supposed to read?

    The King County Department of Information and Administrative Services disclaims any warranty of use of any digital product beyond that which it was designed.

  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 26-Jan-2001
Metadata author:
King County Department of Natural Resources
c/o Michael Leathers
GIS Database Administrator
201 S. Jackson St, Suite 700
Seattle, Washington 98104

206-296-3775 (voice)
206-296-3749 (FAX)

Hours_of_Service: 8:00-4:30 PST M-F
Metadata standard:

Generated by mp version 2.9.6 on Wed Apr 10 12:31:45 2013