-------- 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
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