Flights flown between October 26, 1946 and July 10, 1947 by Woltz Studios, Inc., for the U. S. Dept. of Agriculture, Production and Marketing Administration. Photos numbered BWT-1D-3 through BWT-4D-67. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Jo Daviess County (Ill.) (W 90°40′--W 89°55′/N 42°30′--N 42°12′)
Illinois State Geological Survey
346 remote-sensing images, 2.19 gigabytes, average file 6.88 megabytes
Scanned from 9 x 9 contact prints (nominal scale ca. 1:20,000) on Crosfield Celsis 6200 drum scanning system at 750 dpi. Quality assurance target not published but available by contacting the Illinois State Library Map Dept. MrSID files compressed at a target ratio of 6:1. Uncompressed TIFF images on cd available from the Illinois State Library Map Dept.