For the 6-inch GSD Ortho image, horizontal positional accuracy was designed not to exceed 3.80 feet NSSDA at the 95% confidence level.
This dataset consists of uncompressed, ortho photo tiles formatted as 8-bit, 3-band (RGB), uncompressed, GeoTIFF images with TIF world files. Multi-spectral digital orthophotography was produced at a scale of 1:1200 (1" = 100') with a 6-inch pixel resolution over Ozaukee, Racine, Walworth, Washington, and Waukesha Counties. The project area includes a 1,000-foot buffer extension beyond the county boundaries. The area is covered by 720 complete or partially complete 10,000-foot x 10,000-foot tiles on the Wisconsin State Plane Coordinate System grid, South Zone, NAD 1927.
Imagery for Ozaukee, Washington, and Waukesha counties was also produced on the Wisconsin State Plane Coordinate System grid, South Zone, NAD 1983 (2011), US Survey Feet.
Digital orthophotography combines the image characteristics of a photograph with the geometric qualities of a map. Digital orthophotography is a process which converts a digitized perspective aerial photograph or other remotely sensed image data to a digital product that has been rectified for camera lens distortion, vertical displacement caused by terrain relief and variations in aircraft altitude and orientation.
Aerial photography of the Wisconsin counties was captured during the Spring of 2015 on the following flight dates: April 4, 2015; April 5, 2015; April 11, 2015; April 12, 2015; April 14, 2015; April 18, 2015. The Nominal Acquisition Altitude of 7800 feet (AGL) was used to capture the imagery.
The Microsoft UltraCam Eagle large format digital camera captures three band (RGB) imagery at 16 bits.
The image files for the project area are available in GeoTIFF or MrSID file format. GeoTIFF files covering Ozaukee, Racine, Walworth, Washington, and Waukesha Counties were prepared by Quantum Spatial, inc., and are organized to cover an area of 10,000 by 10,000 feet on the Wisconsin State Plane Coordinate System. GeoTIFF files covering Kenosha and Milwaukee Counties were prepared at 3-inch pixel resolution by Pictometry International Corp. and are organized to cover an area of 5,000 by 5,000 feet on the Wisconsin State Plane Coordinate System. The GeoTIFF files do not contain overlap between adjacent images, and have accompanying "world" (".tfw") files.
The MrSID files are color GeoTIFF files merged into compressed files covering larger areas. Each MrSID file for Ozaukee, Racine, Walworth, Washington, and Waukesha Counties covers approximately one U.S. Public Land Survey System survey township (about 36 square miles). Each GeoTIFF file for Kenosha and Milwaukee Counties covers approximately one-half of a survey township (about 18 square miles). The MrSID files do contain overlap between adjacent images, and have accompanying "world" (".sdw") files.