2012 High-Resolution Natural Color Orthoimagery for the Puget Sound Region (WA) NGA Urban Area

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Frequently-anticipated questions:

What does this data set describe?

2012 High-Resolution Natural Color Orthoimagery for the Puget Sound Region (WA) NGA Urban Area
High-resolution, digital natural color orthoimagery for the Puget Sound, WA region NGA urban area. Comprises approximately 2530 square miles in western Washington (western King County and parts of Snohomish, Pierce, Kitsap, Thurston and Mason Counties). The orthoimagery is provided as1/3 meter resolutionl, 3-band, RGB GeoTiff images. The imagery was collected between March 23, 2012 and May 8, 2012.
The NGA project area is part of a larger project, the 2012 Aerial Mapping Project. The larger project area is approximately 4078 square miles, and encompasses the NGA area plus eastern King County and additional areas of Snohomish and Pierce Counties. The relationship between the two project areas is shown in this project area map - <http://www5.kingcounty.gov/sdc/raster/ortho/images/RegionalMapping_NGA_2012_ProjectExtents.pdf>
  1. How should this data set be cited?

    County, King, 20130523, 2012 High-Resolution Natural Color Orthoimagery for the Puget Sound Region (WA) NGA Urban Area: King County, 201 S Jackson St, Ste 706, Seattle, WA, 98104, USA.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -123.026880
    East_Bounding_Coordinate: -121.837562
    North_Bounding_Coordinate: 46.857915
    South_Bounding_Coordinate: 48.132255

  3. What does it look like?

    <http://www5.kingcounty.gov/sdc/raster/ortho/images/RegionalMapping_NGA_2012_ProjectBrowseSample.pdf> (PDF)
    Sample of 1/3 meter imagery

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

    Beginning_Date: 23-Mar-2012
    Beginning_Time: 000000
    Ending_Date: 08-May-2012
    Ending_Time: 000000
    Ground Condition. Date and time information for when imagery was collected is available. The King County GIS Data Portal site provides access to ORTHO_IMAGE12_POINT as a shapefile or GDB featureclass. This dataset provides an index to all images collected for the entire 2012 Aerials Mapping Project including information about photo time and date. The portal site can be reached at <http://www5.kingcounty.gov/gisdataportal/Default.aspx>

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

    Geospatial_Data_Presentation_Form: raster 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 5001 x 5001, type Pixel

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

      The map projection used is NAD 1983 UTM Zone 10N.

      Projection parameters:

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000000002220024164500956
      Ordinates (y-coordinates) are specified to the nearest 0.000000002220024164500956
      Planar coordinates are specified in Meter

      The horizontal datum used is D North American 1983.
      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?

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?

    Mapcon Mapping, Inc

  3. To whom should users address questions about the data?

    King County GIS Center
    c/o Mike Leathers
    GIS Data Coordinator
    201 S Jackson St, Ste 706
    Seattle, WA 98155

    206-263-4867 (voice)

Why was the data set created?

The U.S. Geological Survey (USGS), as the domestic mapping agency of the United States, needs to obtain current high-resolution orthoimagery coverage over the Puget Sound urban area to meet the needs of Federal partners over 133 urban areas, including the implementation of The National Map. This imagery is collected on behalf of the National Geospatial Intelligence Agency (NGA).
Through this agreement, the USGS will provide funding to King County as part of the local orthoimagery consortium in order to have the region’s 2012 high-resolution digital orthophoto imagery made available in the public domain for access by Federal partners and a broader audience of users through The National Map.

How was the data set created?

  1. From what previous works were the data drawn?

    Digital stereo and digital orthoimagery (source 1 of 1)
    , 20121228, Digital stereo and digital orthoimagery.

    Type_of_Source_Media: hardDisk
    Source_Contribution: Mapcon Mapping

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

    Date: 28-Dec-2012 (process 1 of 2)
    Mapcon Mapping established a flight plan and ground control plan to acquire orthoimagery at 3 resolutions across the Aerial Mapping project area. Three aircraft were used. Two aircraft were used to acquire in the 0.25 foot area and the other acquired in the 0.50 foot and 1.00 foot areas. Both aircraft in the 0.25 foot area used an UltraCamX camera - one which was calibrated 1/6/12 and the other 12/20/10. The aircraft in used for the 0.50 and 1.00 foot areas used an UltraCamXp camera calibrated 5/25/11. Unrectified stereo imagery was delivered for inspection and acceptance. Aerial Triangulation (AT) blocks were created and provided for review. Detailed evaluation of the AT models were performed in selected areas of the 0.25 foot collection, and selected stereo pairs in the 0.50 and 1.00 foot areas were also evaluated using softcopy 3D workstation software. Once accepted, updates to the Digital Elevation Model (DEM) were performed over a large portion of the 0.25 project area. Once the DEM work was finished, ortho production began. State Plane orthoimagery was delivered at three resolutions: 0.25, 0.50 and 1.00 feet.

    Date: 30-Apr-2013 (process 2 of 2)
    To create the UTM 1/3 meter product for the USGS/NGA delivery, the following steps were performed. 1. Combine RGB tifs into one NAD83 HARN Stateplane (SP) Washington North mosaic data set. 2. Identify which 3000 foot tiles in the SP index that lay within the USGS Area Of Interest (AOI) 3. Select SP tile polygon, buffer 12 feet. 4. Extract SP image by buffered tile, resample to .984252 feet (.3 meter) using Bilinear method. 5. Reproject buffered SP image into NAD1983 UTM Zone 10. 6. Clip buffered UTM image with unbuffered tile for clean edge. 7. Copy 16bit UTM RGB image back to 8bit unsigned RGB image with world file and overview files.
    After completion of the UTM tiles, a MrSid lossless version of each tile was created for review. Areas already extensively reviewed by other participants were inspected briefly and areas that were not in participant overlap areas were reviewed to determine that the imagery met the specifications in the scope of work in the USGS/NGA project definition.

  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?

    Ground control and monument information used in the project was compiled. This included control that was used in the Aerial Triangulation build as well as other points. Although not all project areas were equally represented by control, the distribution of points was adequate to confirm the horizontal accuracy of the data.
    A total of 514 control points were matched to visible targets or other identifiable landmarks in the imagery.
    Analysis was performed on the original orthoimage product produced in three resolutions in WA State Plane projection. The 0.25 foot area was evaluated for 395 control points, the 0.50 foot area contained 91 control points and 1.00 foot area contained 28 control points.
    Each resolution was evaluated independently. A standard Root Mean Square (RMS) analysis was performed for each the X differential and the Y differential
    For the 0.25 foot imagery, the RMS error was 0.3104 feet in the X dimension and 0.3101 in the Y dimension. The specification for this resolution is 0.4 foot at 90%; therefore the imagery meets specification.
    For the 0.50 foot imagery, the RMS error was 2.524 feet in the X dimension and 1.3302 feet in the Y dimension. The specification for this resolution is 3.208 feet at 95%; therefore the imagery meets specification.
    For the 1.00 foot imagery, the RMS error was 1.2921 feet in the X dimension and 0.8587 feet in the Y dimension. The specification for this resolution is 5.0 feet at 95%; therefore the imagery meets specification.
    After processing the imagery from the original resolution in State Plane to the UTM 1/3 meter product, these accuracy results translate into an acceptable result required by the NGA specifications of a Horizontal Accuracy not to exceed 5 feet RMSE (X or Y).

  3. How accurate are the heights or depths?

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

    Ortho tiles provide complete coverage to the extent of the NGA Urban Area footprint project area. Each tile in the National Grid spatial index covering the NGA project area has one TIF tile identified as 10TET######.tif, with a corresponding TFW tile. Tiles are all complete imagery except for some bounding tiles where the NGA UTM tiling index does not exactly align with the 2012 Aerials project area.

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

    Each UTM pixel represents a resampling of the original State Plane RGB image pixel.

How can someone get a copy of the data set?

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

Access_Constraints: None
All 12-inch deliverable data and documentation will be free from restrictions for internal USGS use, and distribution to the National Geospatial- Intelligence Agency (NGA). Derivative 2-foot data and documentation provided under this task order shall be free from restrictions regarding USGS use and distribution and shall be freely distributable by government agencies in the public domain.

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

    King County GIS
    c/o Mike Leathers
    GIS Data Coordinator
    201 S Jackson St, Ste 706
    Seattle, WA 98104

    206-263-4867 (voice)

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

  3. What legal disclaimers am I supposed to read?

    See access and use constraints information.

  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 23-May-2013
Metadata author:
King County
c/o Mike Leathers
GIS Data Coordinator
201 S Jackson St, Ste 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 2.9.6 on Thu May 23 18:29:40 2013