Illinois State Geological Survey Unpublished Material Version 2 (2006) raster digital data This data set consists of photo mosaic county indexes of historical black and white aerial photographs from Illinois acquired during the late 1930s and early 1940s. The original paper county indexes have been scanned and saved as TIFF format images. The images available online are MrSID files, in which the original TIFF files were compressed at a target ratio of 10:1 or 6:1 (see process steps "IMAGE COMPRESSION" below). The scale of the data varies from county to county. These data have not been geometrically corrected. These data are provided as supplemental imagery to aid in understanding the organization of the historical aerial photography collections. 1936 1941 publication date Complete As needed -91.675280 -87.483350 42.564692 36.911398 none aerial photography historical imagery black and white scanned MrSID TIFF dpi grayscale none Illinois county Midwest Metro Area Great Lakes none Pre-WWII Pre-World War II WWII World War II 1936 to 1941 1936 1937 1938 1939 1940 1941 1930s 1940s Great Depression Dust Bowl none Reproduction or redistribution of copyrighted digital data sets or products derived there from outside of licensee organization or entity is expressly forbidden. The only exception is redistribution to consultants working for the licensee, and then only for purposes, related to work for the licensee. Such consultants may not further reproduce or redistribute these data sets. None of these data shall be electronically duplicated on magnetic or optical media for use by others, in whole or in part, without permission of the appropriate custodial division within the Illinois Department of Natural Resources (IDNR). Any hardcopies utilizing IDNR data sets shall clearly indicate their source. If the licensee has modified the data in any way they are obligated to describe the types of modifications they have performed on the hardcopy map. Licensee specifically agrees not to misrepresent IDNR data sets, nor to imply that changes they made were approved by IDNR. These data are not to be used for commercial profit. Illinois State Geological Survey Information Office mailing and physical address

615 East Peabody Drive

Champaign Illinois 61820 USA 217-333-4747 217-785-0211 217-244-0802 isgs@isgs.uiuc.edu 8:00 a.m. - 4:30 p.m., Monday-Friday, U.S. Central Time Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 4 Illinois State Geological Survey Unpublished Material raster digital data Champaign, Illinois Illinois State Geological Survey <URL:http://www.isgs.uiuc.edu/ndsihome/outmeta/ilhap_gen.html> Illinois State Geological Survey Unpublished Material vector digital data Champaign, Illinois Illinois State Geological Survey <URL:http://www.isgs.uiuc.edu/ndsihome/outmeta/ilhap_nav.html> Illinois State Geological Survey Unpublished Material raster digital data Champaign, Illinois Illinois State Geological Survey <URL:http://www.isgs.uiuc.edu/ndsihome/outmeta/l_index.html> Not Applicable Not Applicable These data have not been geometrically corrected. These data have not been orthorectified. unknown Unpublished Material raster digital data Champaign, Illinois UIUC Map and Geography Library varies paper 1936 1941 publication date Not Applicable Not Applicable SCANNING METHODOLOGY: Original copies of the county indexes are located at the University of Illinois Map and Geography Library. Special permission was granted by the Library for the county index sheets to be scanned at an offsite location. The indexes were scanned on a large format Eagle 4080 scanner located at the Illinois State Geological Survey. The photo mosaic indexes were scanned at 600 dpi as grayscale images (2001-2004). In December 2004 Historic Information Gatherers, Inc.(HIG), Hopkins, Minnesota, scanned all of the remaining county index sheets (photo mosaic and line indexes that hadn't already been scanned by the ISGS) available at the UIUC Map and Geography Library (~1700 sheets). In Spring 2005 HIG provided the ISGS with digital images of the photo and line indexes. The indexes were scanned on a large format Vidar Titan Atlas P93 scanner temporarily located at the UIUC Map and Geography Library. The photo mosaic indexes were scanned at 300 dpi as indexed color images (2004). 2001-2003 & 2004 IMAGE MANIPULATION (2003-2004): The photo mosaic indexes were downsampled to 300 dpi using Adobe Photoshop ver 7.0. The image was also adjusted for brightness and contrast to make annotations on the image more apparent. 2003-2004 IMAGE MANIPULATION (2006): The image was changed to a grayscale image using Adobe Photoshop ver 7.0. The image was also adjusted for brightness and contrast to make annotations on the image more apparent. 2006 IMAGE COMPRESSION (2003-2004): This methodology was employed for 19 counties that were scanned. These counties include Brown, Bureau, Calhoun, Cass, Champaign, Coles, Cook, Grundy, Johnson, Knox, LaSalle, McHenry, Monroe, Peoria, St. Clair, Sangamon, Union, Vermilion and Will Counties. The original scanned files are archived in TIFF format on CD-ROM at the Illinois State Geological Survey. The files available for download have been compressed using LizardTech's GeoExpress (Solaris platform) MrSID version 1.3.1 software at a compression ratio of 10:1. 2003-2004 IMAGE COMPRESSION (2006): This methodology was employed for 6 counties that were scanned. These counties include Gallatin, Hardin, Pope, Saline, Williamson, and Winnebago Counties. A copy of the original scanned files are archived in TIFF format on CD-ROM at the Illinois State Geological Survey. The files available for download have been compressed using LizardTech's GeoExpress (Solaris platform) MrSID Version 5.0.6.1088.Bob_1055_br software at a compression ratio of 6:1. 2006 Raster Pixel These data are not geometrically corrected. Not Applicable none none none none none Not Applicable Illinois State Geological Survey Information Office mailing and physical address

615 East Peabody Drive

Champaign Illinois 61820 USA 217-333-4747 217-785-0211 217-244-0802 isgs@isgs.uiuc.edu 8:00 a.m. - 4:30 p.m., Monday-Friday, U.S. Central Time A TIFF format file is currently available free of charge at the Illinois Natural Resources Geospatial Data Clearinghouse. Refer to the Identification_Information portion of this file for access to downloadable data and metadata. The Illinois Department of Natural Resources provides these geographic data "as is." IDNR makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. IDNR further makes no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although these data have been processed successfully on computers of IDNR, no warranty, expressed or implied, is made by IDNR regarding the use of these data on any other system, nor does the fact of distribution constitute or imply any such warranty. In no event shall the IDNR have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the geographic data or arising out of the delivery, installation, operation, or support by IDNR. 20060811 Contact_Information Contact_Organization_Primary FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time none none