The black-and-white orthophoto files cover all of the aforementioned area and also cover all of Milwaukee and Waukesha Counties. The black-and-white files were compiled at one-inch-equals-200-feet (1" = 200') scale with a pixel resolution of twelve inches (12"). The image files are available in GeoTIFF or MrSID format. Each black-and-white GeoTIFF format file covers an area of 10,000 by 10,000 feet on the Wisconsin State Plane Coordinate System, South Zone, with zero overlap between images. There are a total of 874 GeoTIFF files in the data set with accompanying "world" (".tfw") files. The MrSID format files were prepared from mosaics of the GeoTIFF format files. Each black-and-white MrSID format file covers an area of one USPLSS township. The 81 MrSID format files contain imagery beyond the boundaries of the survey township and do overlap. The MrSID files have accompanying "world" (".sdw") files.
Finally, there are also seven (7) black-and-white full-county MrSID format orthophoto files in the data set, with each image covering one of the seven counties in the Southeastern Wisconsin Region.
COLOR ORTHOPHOTO FILES:
Each color 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. Each color image file is approximately 72 megabytes in size (with the exception of the 73 image files covering the northern townships of Milwaukee County which are each approximately 286 megabytes in size). The pixel resolution of the images is twelve inches (12") on the ground, with zero overlap between adjacent images (the pixel resolution of the files covering the northern townships of Milwaukee County is six inches [6"] on the ground). The orthophoto 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 orthophoto files were prepared to meet National Map Accuracy Standards (NMAS) for one-inch-equals-200-feet scale (1" = 200' scale) mapping. The entire set of 2,514 color GeoTIFF format files is approximately 192 gigabytes in size.
The 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. Each image file is approximately 160 megabytes in size (with the exception of the two image files covering the northern townships of Milwaukee County which are each approximately 630 megabytes in size). The pixel resolution of the images is twelve inches (12") on the ground, with a minimum of 500 feet of image extending beyond the survey township boundaries (the pixel resolution of the two files covering the northern townships of Milwaukee County is six inches [6"] on the ground). 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 59 color MrSID format files is approximately 10 gigabytes in size.
BLACK-AND-WHITE ORTHOPHOTO FILES:
Each black-and-white (B&W) GeoTIFF file covers a 10,000 by 10,000 foot area or "tile" on the Wisconsin State Plane Coordinate System, South Zone. Each B&W image file is approximately 95 megabytes in size. The pixel resolution of the images is twelve inches (12") on the ground, with zero overlap between adjacent images. The B&W orthophoto files are named similar to the color orthophoto files, and include an accompanying "world" file. The orthophoto files were prepared to meet NMAS for one-inch-equals-200-feet scale (1" = 200' scale) mapping. The entire set of 874 GeoTIFF format files is approximately 81 gigabytes in size.
The B&W MrSID format files were prepared from the B&W GeoTIFF format files. Each MrSID file covers approximately one USPLSS survey township. Each image file is approximately 54 megabytes in size. The pixel resolution of the images is twelve inches (12") on the ground, with a minimum of 500 feet of image extending beyond the survey township boundaries. The files are named with the township and range number of the survey township and include an accompanying "world" file. The entire set of 81 B&W MrSID format files is approximately 4.6 gigabytes in size.
In addition, there is one B&W MrSID format orthophoto file covering each of the seven Southeastern Wisconsin Region counties in this data set. The seven county-wide images cover the entirety of Kenosha, Milwaukee, Ozaukee, Racine, Walworth, Washington, and Waukesha Counties. The entire set of seven (7) B&W county-wide MrSID format files is approximately 4.5 gigabytes in size.