Data files are offered as LizardTech's MrSID Generation 2 .sid files. Target compression ratio is 10:1; one compressed file is roughly 18 megabytes in size.
A statewide collection of both 2005 Chicago Urban Area data and 2005 NAPP (60 Gigabytes) data requires about 100 Gigabytes of storage space. We do not plan to distribute compressed data files by any other means (cd-rom, zip drives, portable drives, ftp download, etc).
Illinois 2005 compressed NAPP DOQ data are available free-of-charge via:
An ArcIMS web service has been created for the Universal Transverse Mercator data collections from the original GeoTIFF files loaded into ArcSDE.
Contact the Illinois State Library(link is external) to obtain indiviual, uncompressed Illinois 2005 orthoimagery files. Note that one statewide coverage of uncompressed 2005 Chicago Urban Area data and 2005 NAPP (680 to 690 Gigabytes) data would require about 1 Terabyte of storage space.