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.
This is a Raster data set. It contains the following raster data types:
The map projection used is NAD 1983 UTM Zone 10N.
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.
Mapcon Mapping, Inc
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.
, 20121228, Digital stereo and digital orthoimagery.
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).
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.
Each UTM pixel represents a resampling of the original State Plane RGB image pixel.
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.
See access and use constraints information.