ImageXXX.tif - Emerge Color Infrared Aerial Photography

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Frequently-anticipated questions:

What does this data set describe?

Title: ImageXXX.tif - Emerge Color Infrared Aerial Photography
Low elevation, high resolution (i.e, small ground-sample-distance (GSD)) aerial photography collected in late spring to early fall 2000 for western King County and southwestern Snohomish County (approx. 1170 sq. miles). The data has a pixel sixe of 2 feet. The data is 8-bit,three band (green, red, near infrared) and displays for default viewing in ArcView as an infrared ('false color') display. A natural color derivative version has also been made available and is described in separate metadata.
The images are provided in the their original 3-band 'false color' version as delivered by the vendor. The data was reprojected as discussed in the process section, but no additional image enhancement nor display adjustments was performed. Pyramid files were created to improve displaly performance in Erdas and ArcView Image Analyst. The .rrd pyramid files are stored with the data or available on supplemental CDROM accompanying the data. The images can be accessed as individual TIFFs file by file, as a pseudo-mosaic by using the associated image catalog dbase file (emerge_cir.dbf), where supported. Each image tile covers approximately 3.58 sq. miles, are is approximately 75 mb in size. The entire dataset requires approximately 22.6 gb of storage for the TIFF and TFW files, with another 4 gb required for the RRD pyramid files. The actual file count of 373 image files does not match the filename maximum
  1. How should this data set be cited?

    County, King, 20010501, ImageXXX.tif - Emerge Color Infrared 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 Emerge dataset component was captured and delivered to Pacific Meridian by Emerge, Inc, an aerial photography firm. Licensing and use restrictions are part of this acquisition effort. Please contact the Point of Contact for licensing restrirctions.
    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?

  3. What does it look like?

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

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

    Geospatial_Data_Presentation_Form: Map

  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 5100 (representative) x 5100 (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 table. The Vendor supplied no metadata information except for acquisition date when the data was delivered. Subsequent inquiries regarding the data have produced some general background information on the capture and sensor parameters.The sensor used is Eastman Kodak DSC460CIR imager with a 3072 x 2048 pixel focal plan array. The sensor incorporates a bandpass filter on the lens that has a -3dB cutoff for wavelengths of less than 500 nm and greater than 800 nm. Blue light is outside the filter's bandpass, so that none of the incident blue light reaches the sensor. The red,green and blue filter elements are all transparent to the reflected NIR radiance passed in the 700 to 800 nm region. Thus, the green filtered pixels respond to green and NIR, the red filtered array elements respond to red plus NIR radiance, while the blue-filtered pixels respond to NIR radiance only. The results obtained by

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?

Why was the data set created?

This image dataset comprises 373 individual image tiles stored in TIFF format that can be displayed as a single seamless mosaic. The imagery, within the horizontal accuracy and resolution limitations, serves as digital backdrop imagery for GIS, cartographic production and image analysis. 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 data.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)

    Online Links:

    This is part of the following larger work.


    Online Links:

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

    (process 1 of 1)
    The images were received from the vendor on CD-ROM as 3 band (green, red, near infrared) 'false color' images as as a single TIFF file with world file. The imagery was delivered

  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 the contract specification for 1:10000 NMAS with a CE90 of 4 m (13.1 feet) accuracy. However the absolute accuracy varies significantly across the project area. In general, areas in the northern one-third of the project area exhibit greater variance from known ground control than in the balance of the project area. The error allowance in the northern one-third area approaches the CE90 limit, while the southern two-thirds area has a error range from under 2 feet up to 7 feet.

  3. How accurate are the heights or depths?

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

    The 373 image tiles in the dataset cover the entire area of interest (AOI) as supplied by King County to the Vendor. The portion of Snohomish County that is covered with this dataset is that part of WRIA (Watershed Resource Inventory Area) 8 that extends from King County into Snohomish County. The AOI, however, did not provide for any buffer at the edges of this WRIA nor along any of the other AOI edges, either with adjacent counties or Puget Sound. For this reason the imagery is truncated abruptly along these edges. Also due to this truncation along Puget Sound, there is no or very little extension of the imagery into the near shore zone.

  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?

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

    King County
    c/o Cheryl Wilder
    700 5th Ave, Ste 2300
    Seattle, WA 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?

    imageXXX.tif where XXX references a tile_id linked to a single polygon in idxpemer.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 which it was designed.

  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 01-May-2001
Metadata author:
King County Department of Natural Resources
c/o Michael Leathers
GIS Database Administrator
201 S. Jackson St, Ste 700
Seattle, WA 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 12:31:47 2013