{7DCB9E75-75E8-4993-8519-99A1F07A0761} 20050808 12092000 FALSE 20070831 10372700 20070831 10372700 ESRI ArcCatalog 9.2.2.1350 en This data represents a panchromatic county orthophoto mosaic in MrSID image format produced from black and white aerial photographs of a particular Iowa county. This county mosaic was developed from individual aerial images taken during the late 1930s and early 1940s by the Agricultural Adjustment Administration (AAA), part of the US Department of Agriculture. The images were originally photographed at 1:20,000 scale, were digitally scanned from hardcopy prints at various scales and from various sources, and for this purpose were cast on the Universal Transverse Mercator Projection (UTM) on the North American Datum of 1983 (NAD83). These are wavelet-compressed raster format images at a resolution of 1 meter. Orthophotos combine the image characteristics of a photograph with the geometric qualities of a map. Digital orthophotos serve a variety of purposes, from interim maps to references for earth science investigations. The images are useful as a layer of a geographic information system and as a tool for revision of digital graphs and topographic maps. This data set is particularly useful to indicate the historic usage and condition of the land. This photographic dataset represents the earliest photographic record of the entire State of Iowa. This digital, geographically referenced data set was developed by the Iowa Department of Natural Resources to carry out agency responsibilities related to management, protection, and development of Iowa's natural resources. Work on the rectification of this historic photography began in 2005. Planning for this project began several years earlier, but it took several years to acquire special scanning equipment and get all arrangements in place. In the first year, 10 counties were completed, using a classical georectification approach. In the second year, an orthorectification approach was adopted, and additional teams were added to the project. As of August 2006, approximately a quarter of the state is in some form of completion. Iowa Department of Natural Resources 1930s_airphotos_49.sid raster digital data withheld http://www.igsb.uiowa.edu/nrgislibx/ Iowa City, Iowa Iowa Department of Natural Resources Historic Aerial Photography 1930s Zip file contains other files pertinent to this dataset withheld ground condition 1936 1941 Complete As needed -90.935786 -90.106357 42.434671 41.994581 670925.000000 738083.000000 4653172.000000 4700131.000000 aerial photography county mosaic digital orthophotgraphy digital image map none ISO 19115 Topic Category imageryBaseMapsEarthCover Jackson County, Iowa GNIS 1930s None None The development of the coverages in the NRGIS Library represents a major investment of staff time and effort. As a professional responsibility, the Iowa DNR expects to receive proper credit when these GIS coverages are utilized. The Department also expects that the original documentation will remain with any redistribution of these coverages. Raster Dataset Iowa Department of Natural Resources Kathryne Clark mailing and physical address IA

Wallace State Office Building

Des Moines 50319 (515) 281-4583 kclark@dnr.state.ia.us GIS Analyst GIS Laboratory, Iowa State University Unpublished Material geodatabase Working geodatabase developed by ISU GIS Lab to support the process of scanning and rectifying 1930s photography. Partial funding for the development of this data was received from the Iowa DNR's Brownfields program, which receives funding from the USEPA. The Iowa State University GIS Lab did the scanning of the photography. ESRI ArcCatalog 9.2.2.1350 1930s_airphotos_49.sid 670925 738083 4700131 4653172 1 -90.935786 -90.106357 42.434671 41.994581 1 en FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time mailing and physical address Iowa City IA 52242

109 Trowbridge Hall

319-335-1353 GIS Librarian gis_library@igsb.uiowa.edu 0800-1630 CDT CST Iowa Geological Survey - IDNR 20070831 None None http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile ISO 19115 Geographic Information - Metadata DIS_ESRI1.0 dataset Downloadable Data 130.896 130.896 http://www.igsb.uiowa.edu/nrgislibx/ withheld withheld Iowa Geological Survey - IDNR GIS Librarian mailing and physical address

109 Trowbridge Hall

Iowa City IA 52242 319-335-1353 gis_library@igsb.uiowa.edu Although efforts have been made in correcting errors in order to make this information useful to the Department, the Department assumes no responsibility for errors in the information. Similarly, the Department assumes no responsibility for the consequences of inappropriate uses or interpretations of the data made by anyone to whom this data has been made available. The Department bears no responsibility to inform users of any changes made to this data. Anyone using this data is advised that precision implied by the coverage may far exceed actual precision. Comments on this data are invited and the Department would appreciate that documented errors be brought to staff attention. 365 days/year 24 hrs/day 002 withheld Local Area Network 130.896 Raster Dataset Raster Pixel 46959 67158 1.000000 1.000000 8 1 Upper Left FALSE Wavelet 1 pixel codes TRUE MrSID GCS_North_American_1983 NAD_1983_UTM_Zone_15N row and column meters 1.000000 1.000000 Universal Transverse Mercator 15 0.999600 -93.000000 0.000000 500000.000000 0.000000 North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 NAD_1983_UTM_Zone_15N 2 1 44703 1 Meter 1 Meter = 1 Meter(s) 41458 1 Meter 1 Meter = 1 Meter(s) Table 1 ObjectID ObjectID OID 4 0 0 Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Value Value Integer 0 0 0 Count Count Double 0 0 0 Band_1 Table 255 ObjectID ObjectID OID 4 0 0 Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Value Value Integer 0 0 0 Count Count Integer 0 0 0 20070831 Image brightness values may deviate from brightness values of original imagery due to image value interpolation during scanning, rectification, and mosaicking processes. Contrast and brightness differences are normalized during the mosaic process to produce a more consistent appearance. In some cases, imagery from significantly different dates (usually within a year of each other) make up a single county, lending a somewhat discontinuous appearance. No formal positional accuracy assessment has been done. However, many factors apply to the accuracy of this data: The horizontal positional accuracy and the assurance of that accuracy depend, in part, on the accuracy of the data inputs to the rectification process. These inputs consist of the digital elevation model (DEM),aerotriangulation control and methods, the photo source camera calibration, scanner calibration, and aerial photographs that meet National Aerial Photography Program (NAPP) standards. The vertical accuracy of the verified USGS format DEM is equivalent to or better than a USGS level 1 or 2 DEM, with a root mean square error (RMSE) of no greater than 7.0 meters. Horizontal control was derived from the 1990s DOQQs. Vertical control from the 10 meter USGS DEM, derived from the 1:24,000 topographic map series contours. The process of collecting control points from historical imagery is intrisically fraught with difficulty. Man made features, especially road intersections, are the best control points, yet nearly every one of these features has changed in some way in the intervening time period, some significantly, which can reduce the accuracy of these points, and hence of the entire rectification process. This problem becomes exacerbated in areas where there are fewer good control points, such as in many counties near the Mississippi River. 20,000 on film Photographic prints on paper 1936 1941 ground condition Panchromatic black and white aerial photographs. Agricultural Adjustment Administration A good description of the project that produced this data can be found at: http://faculty.maxwell.syr.edu/mon2ier/e_reprints/PEARS_Dec_02_AAA.pdf Unknown hard-copy aerial photographs Because the source photography was taken in the 1930s, and was celluloid-based, none of the original transparencies are still extant. The original size of the transparency for most of the images was 7x9 inches. All of this photography was scanned from photographic prints on paper, which is a more durable medium. The photos were collected from a variety of sources. The files of the Department of Transportation (DOT) and the USDA Natural Resources Conservation Service (NRCS) were the primary sources. Most images from these sources were originally photoenlarged to scales as large as 19x24 inches. Images not available from these sources were located elsewhere, including the University of Iowa Map Library, and the National Archives. All scanning was done at 600 dpi on a high quality scanner. For the first 10 counties, the largest by population, a georeferencing process was used to rectify the imagery. Leica's Erdas IMAGINE software was used to collect control points. This process was used for Black Hawk, Clinton, Dubuque, Johnson, Linn, Polk, Pottawattamie, Scott, Story, and Woodbury counties, all completed in 2005. Counties produced by this process will often exhibit small discontinuities of linear features near image edges. For all the remaining counties, an orthorectification process was utilized, using the Leica Photogrammetry Suite. This photogrammetric approach utilizes a block adjustment approach, and reuses control points on neighboring images to minimize displacement at photo edges. Rectified images are resampled to a spatial resolution of 1 meter, then clipped to remove edges, before being mosaicked into full county mosaics, and compressed into MrSid format. The mosaic process was performed with the Inpho OrthoVista software. All images for a single county were brought to a common brightness and contrast, then mosaicked using adaptive feathering. Leica Erdas Imagine, Leica Photogrammetry Suite, v.8.7 and v.9.0 2006 R. Peter Kollasch Iowa DNR, GIS Section Remote Sensing Analyst (319) 335-1578 pkollasch@igsb.uiowa.edu This collection represents conditions in the state of Iowa between the years 1936 and 1941. Imagery were collected on a county-by-county basis. Within a county, usually the entire county was collected within a narrow time frame, but in some instances, perhaps due to poor image quality or lack of coverage, areas were reflown at a later time. Between counties there is less consistency, because flight times were variable, and may have occurred in different years. Different contractors, aircraft, cameras, and procedures were used, producing variations in quality. There are also inconsistencies in the rectification process. As referenced elsewhere, the first 10 counties processed were produced by a classical georeferencing approach. Later counties were done by a photogrammetric block adjustment approach, which produces greater consistency within each block. Imagery from this time period is available for the entire state. The rectification process has been completed for approximately one quarter of the counties (August 2006). Work continues. minimal Iowa State University GIS Lab Live Data and Maps 130.896 130.896 http://cairo.gis.iastate.edu IMS Administrator 515-281-5843 Iowa Department of Natural Resources Live Data and Maps Although efforts have been made in correcting errors in order to make this information useful to the Department, the Department assumes no responsibility for errors in the information. Similarly, the Department assumes no responsibility for the consequences of inappropriate uses or interpretations of the data made by anyone to whom this data has been made available. The Department bears no responsibility to inform users of any changes made to this data. Anyone using this data is advised that precision implied by the coverage may far exceed actual precision. Comments on this data are invited and the Department would appreciate that documented errors be brought to staff attention. 130.896 130.896 http://www.iowadnr.gov/ Go to "Mapping (GIS Interactive)" on the left-hand menu, then to the Basic Map