-------- Original Message -------- Subject: Illinois Historical Aerial Photography Digital Archive Keeps Growing Date: Mon, 15 Nov 2004 11:12:16 -0600 From: Booth, Arlyn <[log in to unmask]> To: <[log in to unmask]> ------------------ For immediate release November 12, 2004 Further information: Don Luman 217/244-2179 Arlyn Booth 217/558-4140 Illinois Historical Aerial Photography Digital Archive Keeps Growing SPRINGFIELD, Illinois--The Illinois Historical Aerial Photography Digital Archive, representing the earliest statewide aerial photography acquired during 1938-1941, has grown with the addition of twenty more counties. Forty-five counties comprising a total of 15,921 aerial photographs are now accessible through the Illinois Geospatial Data Clearinghouse located at http://www.isgs.uiuc.edu/nsdihome/webdocs/ilhap/. The aerial photographs for the latest 20 counties added to the web site, most of which are situated adjacent to the Illinois River, were funded by an Institute for Museum and Library Services (IMLS) grant to the Illinois State Library (ISL) and the Illinois State Geological Survey (ISGS). The ArcIMS interactive map service web pages have been significantly updated with new layers aiding search strategy, including the USGS 7.5-minute topographic map index, USGS Digital Raster Graphic (DRG) files, and the 1998-2001 Digital Orthophoto Quarter Quadrangle (DOQQ) imagery. Record-level metadata is available for each aerial photograph. Access and search of the aerial photography is also provided via text-based web pages for each of the 45 counties. Scantech Imaging of Champaign, Illinois scanned the 7 x 9 and 9 x 9 inch paper prints, acquired from various aerial photography collections around the state, at 750 dpi in an 8-bit grayscale range, using a Crosfield 646IE drum scanning system. The county indexes were scanned on a large-format document scanner and have been georeferenced to serve as the basis for accessing and searching the digital archive. The individual aerial photographs have not been georeferenced in order that they may serve as digital surrogates of the original prints, and so that stereoscopic viewing capability is maintained. All of the aerial photographs and county indexes are available for free download on the website. The aerial photographs are compressed into MrSID-formatted images, with an ExpressView Browser plug-in available on the web site for download. The original uncompressed TIFF images will be available on CD-ROM from ISL in the future. ISL and ISGS hope to attract funding to eventually scan the oldest aerial photography for the remaining 57 Illinois counties. The goal is to preserve the oldest statewide aerial photographs first, since their original negatives no longer exist and paper collections are deteriorating. When the 1938-1941 aerial photographs for Illinois are preserved, it is hoped that efforts can then turn to making later flights accessible via the Web. from Arlyn Booth Map Coordinator Illinois State Library 300 S. 2nd, Rm. 305 Springfield, IL 62701-1796 (217) 558-4140 FAX (217) 557-6737 [log in to unmask] Jesse White, Secretary of State & State Librarian