The orthophoto files were prepared at three different pixel resolutions for three distinct project areas: 1) Twelve-inch pixel resolution, one-inch-equals-200-feet scale orthophotos were prepared for Ozaukee County (excluding City of Mequon area), Racine County, and Walworth County; 2) Six-inch pixel resolution, one-inch-equals-100-feet scale orthos were prepared for Milwaukee, Washington, and Waukesha Counties and for the City of Mequon area; and 3) Three-inch pixel resolution, one-inch-equals-50-feet scale orthos were prepared for Kenosha County.
The image files for all three project areas are available in GeoTIFF or MrSID file format. GeoTIFF files in the 12-inch and 6-inch project areas are organized to cover an area of 10,000 by 10,000 feet on the Wisconsin State Plane Coordinate System. GeoTIFF files for the 3-inch project area (Kenosha County) 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 in the 12-inch and 6-inch project areas covers one U.S. Public Land Survey System survey township (about 36 square miles). Each GeoTIFF file in the 3-inch project area (Kenosha County) 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.
"U.S. Department of Commerce, 1995, Countries, dependencies, areas of special sovereignty, and their principal administrative divisions, Federal Information Processing Standard (FIPS) 10-4: Washington, D.C., National Institute of Standards and Technology."
"U.S. Department of Commerce, 1987, Codes for the Identification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standard (FIPS) 5-2: Washington, D.C., National Institute of Standards and Technology." {{ preceeding citations from file-level metadata prepared by project contractor Aero-Metric, Inc. }}
"Orthoimages are visually inspected for completeness to ensure that no gaps or image misplacements exist within and between adjacent images. These images are derived by mosaicking multiple images to ensure complete coverage. Source imagery is cloud free." {{ preceeding citation from file-level metadata prepared by project contractor Aero-Metric, Inc. }}
TWELVE-INCH RESOLUTION PROJECT AREA (most of Ozaukee County, Racine County, Walworth County)
The orthophoto images in this project area were prepared to meet National Map Accuracy Standards for one-inch-equals-200-feet scale (1:2400 scale) mapping. The resolution of each pixel in the files is twelve inches (12") on the ground. Ninety percent or more of all well-defined planimetric features visible in these orthophoto files are within approximately eight feet (8') of their true position on the ground.
SIX-INCH RESOLUTION PROJECT AREA (Milwaukee, Washington, and Waukesha Counties, City of Mequon area)
The orthophoto images in this project area were prepared to meet National Map Accuracy Standards for one-inch-equals-100-feet scale (1:1200 scale) mapping. The resolution of each pixel in the files is six inches (6") on the ground. Ninety percent or more of all well-defined planimetric features visible in these orthophoto files are within approximately four feet (4') of their true position on the ground.
THREE-INCH RESOLUTION PROJECT AREA (Kenosha County)
The orthophoto images in this project area were prepared to meet National Map Accuracy Standards for one-inch-equals-50-feet scale (1:600 scale) mapping. The resolution of each pixel in the files is three inches (3") on the ground. Ninety percent or more of all well-defined planimetric features visible in these orthophoto files are within approximately two feet (2') of their true position on the ground.
"The DMC images were aerotriangulated to support digital ortho image production for the Milwaukee, Washington, and Waukesha County SEWRPC project area. Airborne GPS and ground check point data was provided by AERO-METRIC, Inc. The project was referenced to the North American Datum of 1927 (NAD27), State Plane Coordinate System, Wisconsin South Zone horizontally and to the National Geodetic Vertical Datum of 1929 (NGVD29) vertically. Units were in U.S. survey feet. The DMC images, ABGPS/IMU data, and ground check point data were used as inputs to the INPHO MATCH-AT softcopy program. MATCH-AT correlated image points and aerotriangulated the block of images to create exposure station exterior orientations. All ground points were manually measured on the imagery. These points were included in the aerotriangulation adjustments for absolute ground location verification. The scale of the aerial photos was 1:12,696. The photography was exposed between 3/30/10 and 4/19/10.
Rectification was done using the aerotriangulation data, raw DMC images, and updated SEWRPC Ortho Elevation Model (OEM) data. These rectified images were used to generate seamlines which were then reviewed and edited . The images were then dodged. The dodged rectified images were mosaicked, balanced, and cut into image tiles. These tiles were viewed and artifacts were removed as well as other edits performed. Then the edited tiles were mosaicked together and the final tiles were cut out." {{ preceeding citation pertaining to six-inch project area imagery from file-level metadata prepared by project contractor Aero-Metric, Inc. }}
TWELVE-INCH RESOLUTION PROJECT AREA
The 12-inch orthophoto project area covers Ozaukee County (excluding the City of Mequon area), Racine County, and Walworth County (with portions of adjacent counties). The images were prepared to meet National Map Accuracy Standards for one-inch-equals-200-feet scale (1:2400 scale) mapping. The resolution of each pixel in the files is twelve inches (12") on the ground.
Each 12-inch resolution GeoTIFF (Tagged Image File Format) file covers a 10,000 by 10,000 foot area or "tile" on the Wisconsin State Plane Coordinate System, South Zone, with zero overlap betweeen images. The individual image files are approximately 286 megabytes in size. The GeoTIFF files are named according to the Wisconsin State Plane Coordinate System easting coordinate and northing coordinate, in thousands of feet, of the southwest corner of the image. Each image file includes an accompanying ESRI-format "world" file (".tfw" file extension) containing the coordinate information used to display and register the image in ESRI software. The entire set of 398 twelve-inch GeoTIFF format files is approximately 112 gigabytes in size.
The 12-inch resolution color MrSID (Multi-Resolution Seamless Image Database) format files were prepared from the GeoTIFF format files. Each MrSID file covers approximately one U.S. Public Land Survey System (USPLSS) survey township, with a minimum of 500 feet of image extending beyond the survey township boundaries. The individual image files are approximately 160 megabytes in size. The files are named with the township and range number of the survey township. Each image file includes an accompanying ESRI-format "world" file (".sdw" file extension) containing coordinate information used to display and register the image in ESRI software. The entire set of 33 twelve-inch MrSID format files is approximately 6 gigabytes in size.
SIX-INCH RESOLUTION PROJECT AREA
The 6-inch orthorthophoto project area covers Milwaukee County, Washington and Waukesha Counties (with portions of adjacent counties), and the City of Mequon area. The images were prepared to meet National Map Accuracy Standards for one-inch-equals-100-feet scale (1:1200 scale) mapping. The resolution of each pixel in the files is six inches (6") on the ground.
Each 6-inch resolution GeoTIFF (Tagged Image File Format) file covers a 10,000 by 10,000 foot area or "tile" on the Wisconsin State Plane Coordinate System, South Zone, with zero overlap betweeen images. The individual image files are approximately 1.1 gigabytes in size. The GeoTIFF files are named according to the Wisconsin State Plane Coordinate System easting coordinate and northing coordinate, in thousands of feet, of the southwest corner of the image. Each image file includes an accompanying ESRI-format "world" file (".tfw" file extension) containing the coordinate information used to display and register the image in ESRI software. The entire set of 439 six-inch GeoTIFF format files is approximately 482 gigabytes in size.
The 6-inch resolution color MrSID (Multi-Resolution Seamless Image Database) format files were prepared from the GeoTIFF format files. Each MrSID file covers approximately one U.S. Public Land Survey System (USPLSS) survey township, with a minimum of 500 feet of image extending beyond the survey township boundaries. The individual image files are approximately 640 megabytes in size. The files are named with the township and range number of the survey township. Each image file includes an accompanying ESRI-format "world" file (".sdw" file extension) containing coordinate information used to display and register the image in ESRI software. The entire set of 38 six-inch MrSID format files is approximately 24 gigabytes in size.
THREE-INCH RESOLUTION PROJECT AREA
The 3-inch orthophoto project area covers Kenosha County (with portions of adjacent counties). The images were prepared to meet National Map Accuracy Standards for one-inch-equals-50-feet scale (1:600 scale) mapping. The resolution of each pixel in the files is three inches (3") on the ground.
Each 3-inch resolution GeoTIFF (Tagged Image File Format) file covers a 5,000 by 5,000 foot area or "tile" on the Wisconsin State Plane Coordinate System, South Zone, with zero overlap betweeen images. The individual image files are approximately 1.1 gigabytes in size. The GeoTIFF files are named according to the Wisconsin State Plane Coordinate System easting coordinate and northing coordinate, in thousands of feet, of the southwest corner of the image. Each image file includes an accompanying ESRI-format "world" file (".tfw" file extension) containing the coordinate information used to display and register the image in ESRI software. The entire set of 386 three-inch GeoTIFF format files is approximately 424 gigabytes in size.
The 3-inch resolution color MrSID (Multi-Resolution Seamless Image Database) format files were prepared from the GeoTIFF format files. Each MrSID file covers approximately one half of a U.S. Public Land Survey System (USPLSS) survey township, with a minimum of 500 feet of image extending beyond the half-survey-township boundaries. The individual image files are approximately 1.3 gigabytes in size. The files are named with the township and range number of the survey township and a suffix ( 'N' or 'S' ) identifying the north or south half of the survey township. Each image file includes an accompanying ESRI-format "world" file (".sdw" file extension) containing coordinate information used to display and register the image in ESRI software. The entire set of 15 three-inch MrSID format files is approximately 21 gigabytes in size.