Missouri River 2000 Digital Orthophotographs
Sioux City Iowa to the Mouth at St. Louis, Missouri
The United States Army Corps of Engineers, Kansas City and Omaha Districts, contracted with Western Air Maps, Inc. to produce color digital orthophotography of the Missouri River from Sioux City, Iowa to the mouth north of St. Louis, Missouri. The photography was acquired in March through May, 2000 to provide an orthobase for Corps of Engineers Missouri River mapping activities. The orthophoto mosaics were compressed using MrSid image compression software.
You need to download two files per image; the *.sid image file and the *.sdw world file. At a later date, a metadata file (*.met) will be available for each image. The world file can be viewed in a text editor and includes information on resolution and coordinates of the image origin. The original project projection was UTM, Zone 15, NAD83, FEET. This information is included in the image header. We have reprojected to UTM, Zone 15, NAD83, METERS and modified the world file to reflect this change. If you wish to use the data in the original format (feet), remove the world file (*.sdw) to another directory and the image header information will provide this option. If, on the other hand, you wish to use meters, the world file must be present in the same directory as the image file.
The MrSid.dll file distributed with ArcView GIS pre-version 3.3 does not read the MrSID world file (.sdw). ArcView users should check the version of the AV_MrSID.dll located in the ESRI\AV_GIS30\ARCVIEW\BIN32 directory. If the version is pre 188.8.131.52, the user should go to: http://www.lizardtech.com/products/updates.html and download the most recent version. In order to take advantage of the external world file (units in meters), you must download a new version of the AVMrSID.dll and place it in the bin32 directory.
Note: Make sure that you have the MrSID ArcView extension loaded in order to use the files.
Unless you have a high speed connection (T1, DSL, Cable), you probably do not want to try to download the image files. Contact Mark Laustrup, (firstname.lastname@example.org) USGS Columbia Environmental Research Center, River Studies Station for information on other options.