Aerial photographs of the Mississippi River were acquired in 1927 as a response to the
Flood of 1927. This collection history gives details about why the photos
were originally taken, why only part of the collection has been scanned and much more. Currently, original negatives
for these photographs have not been located. Due to this fact the original photographic prints are now the best
substitute for the negatives. Use of the paper prints over time has resulted in their becoming faded, worn, defaced,
or lost. Access to the print collection, currently available on this website, can be obtained through the US Army
Corps of Engineers - Rock Island District (the collection
does not circulate).
Digitization, or print scanning, has been completed for a Pools 11 through 19 of the Upper Mississippi River in an effort to create a lasting archive of this irreplaceable collection. Other images from other Pools may be added in the future if the remaining photos become available. The aerial photographs have not been georeferenced. Photographs that overlap can be used for stereoscopic viewing.
JPEG File Format
This format is a compressed file with the following file extension
.jpg. The original TIFF format files were compressed using Adobe
Photoshop CS4 and their Quality setting was set to 10. The average file size is approximately 9.0 megabytes for each 7x9 inch photos. These files should open in most browsers as they are an open source file format. These files have not been georeferenced.
MrSID File Format
This format is a compressed digital file with the following file extension
.sid. The original TIFF format files were compressed
using LizardTech's GeoExpress software in Generation 2 .sid file format at a target compression ratio of 6:1. The resulting average file
size is 6.25 megabytes for each 7x9 inch photos. These files require a special viewer (ExpressView browser plug-in, available below) in order
to view them online. They will also open in some mapping software (despite not being georeferenced) once they have been downloaded. The
ExpressView browser plug-in is not available for Macintosh OS X or higher and is getting increasingly difficult to find for Mac OS versions
earlier than OS X. The plugin does not work with Google Chrome. These files have not been georeferenced.
TIFF File Format
This format is a full resolution file format with the following file extension
.tif. These are the original uncompresed files.
They were scanned at 750dpi on a Crosfield Drum scanner. The average file size is approximately 37.0 megabytes for each 7x9 inch photos. These files require a browser plugin to be viewed online. Many
software programs will be able to view the images once they are downloaded. These files have not been georeferenced.
Please read the license agreement. This link also provides citation information.
Each photograph has an exposure number labebled on the photo. Naming conventions for the digital files include a code for the Upper Mississippi River (UMR) and an exposure number; zeros are used as placeholders.
|Example: The file named UMR0405.sid is labeled 405 on the photograph.|
|Code:||UMR||= Upper Mississippi River|
|Exposure Number:||0405||= Exposure 405|
Project funding was contributed by:, , , Jo Daviess County Soil and Water Conservation District, and .