Iowa Department of Natural Resources raster digital data Historic Aerial Photography 1970s Iowa City, Iowa Iowa Department of Natural Resources Zip file contains other files pertinent to this dataset withheld 1970s_airphotos_74.sid 20120131 20120131 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 1970s by the Agricultural Stabilization and Conservation Service, part of the US Department of Agriculture. The images were originally photographed at 1:38,000 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 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. en 19730515 ground condition Complete As needed -94.926416 -94.432417 43.264081 42.899312 343635.000000 383068.000000 4751413.000000 4791149.000000 ISO 19115 Topic Category imageryBaseMapsEarthCover GNIS Palo Alto County, Iowa None 1970s 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. Kathryne Clark Iowa Department of Natural Resources GIS Analyst mailing and physical address

Wallace State Office Building

Des Moines IA 50319 (515) 281-4583 kclark@dnr.state.ia.us Partial funding for the development of this data was received from the Iowa DNR's Brownfields program, which receives funding from the USEPA, and the State Historical Society. The scanning was conducted by USDA NRCS Soil Survey Office staff in Ames and Des Moines, IA Orthorectification was carried out by USDA NRCS Soil Survey Office staff in Ames and Des Moines, IA. Project coordination was done by Andy Asell. State of Iowa Enterprise Data Classification Standard Public ESRI ArcCatalog 9.3.1.4000 GIS Section, IGWS, DNR Unpublished Material geodatabase Working geodatabase developed by Andy Asell of the GIS Section to support the process of scanning and rectifying 1970s photography. Raster Dataset 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. This collection represents conditions in the state of Iowa in the 1970s. 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. Imagery from this time period is available for the entire state. Not all counties may be completed at this time 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 2007 Color-Infra-Red Aerial Photography. 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. Agricultural Stabilization and Conservation Service University of Iowa Map Collection was the Primary source of copies of Photography Secondary Sources include: County Engineers offices, NRCS, Iowa DOT, Iowa State University Map Room, USDA - FSA - Aerial Photography Field Office, National Archives 1970-1965 aerial photograph (hard copy) 38,000 on film Photographic prints on paper 1970 1965 ground condition Panchromatic black and white aerial photographs. The photos were collected from the USDA Natural Resource Conservation Service. Photo restoration was done prior to scanning. This involved erasing grease-pencil notation markings made on the photos. All scanning was done at 1100 dpi on a high quality scanner. An orthorectification process was utilized, using OrthoMapper software by Image Processing Software. This photogrammetric approach utilizes a block adjustment approach, and reuses control points on neighboring images to minimize displacement at photo edges. Along with control points, tie points were used to more seamlessly connect neighboring images together Rectified images are resampled to a spatial resolution of 1 meter, then clipped to remove edges, header and fiducial marks, 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. 2011 Cody Hackney Iowa DNR, GIS Section GIS technician (319) 335-1575 cody.hackney@dnr.iowa.gov withheld Digital Aerial Photography Horizontal control. 2007 ground condition USGS withheld Digital Raster Data Verticle control. minimal Raster Pixel 39736 39433 1 1.000000 1.000000 8 Upper Left FALSE Wavelet (MG2) 1 pixel codes MrSID TRUE row and column 1.000000 1.000000 meters 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 GCS_North_American_1983 NAD_1983_UTM_Zone_15N 1970s_airphotos_74.sid.vat Table 256 OID OID 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 ObjectID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Value Count Iowa State University GIS Lab Live Data and Maps 130.896 http://cairo.gis.iastate.edu Iowa Department of Natural Resources IMS Administrator 515-281-5843 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 http://www.iowadnr.gov/ Go to "Mapping (GIS Interactive)" on the left-hand menu, then to the Basic Map Iowa Geological and Water Survey - IDNR GeoSpatial DBA / NRGIS Librarian mailing and physical address

109 Trowbridge Hall

Iowa City IA 52242 319-335-1575 gis_library@igsb.uiowa.edu Downloadable Data 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. MrSid Image Image file and zip file which contains ancillary files zip 130.896 withheld None Click on anonymous FTP link provided. Immediate 365 days/year 24 hrs/day Iowa Geological and Water Survey, DNR NRGIS Librarian mailing and physical address

109 Trowbridge Hall

Iowa City IA 52242 319-335-1575 gis_library@igsb.uiowa.edu 0800-1630 CDT CST FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time None None 20120124 en http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile 20120124 10301800 20120123 21532600 20120124 ESRI ArcCatalog 9.3.1.4000 1970s_airphotos_74.sid 343635 383068 4791149 4751413 1 -94.926416 -94.432417 43.264081 42.899312 1 ISO 19115 Geographic Information - Metadata DIS_ESRI1.0 dataset withheld Local Area Network 002 Raster Dataset NAD_1983_UTM_Zone_15N