Historic Aerial Photo Orthorectification

Orthorectification is the process by which an aerial photo is geometrically corrected to produce maplike qualities. Errors produced from lens distortion and topographic relief are removed so that true distances can be measured. The resulting orthophoto is used as a basemap for GIS and CAD projects. There are many sources of orthophotos from the past decade; however, historic orthophotos are rare.

Historic aerial photos are an invaluable tool to understanding the past. These photos are available through federal and state agencies dating from the 1930's to today. These uncorrected historic aerial photos cannot be used as an accurate basemap. If you need higher accuracy for your historic aerial photos, OSGIS can help.

Pennsylvania is one of the first states to have scanned historic aerial photos. Photos are available for all parts of the state for two time periods, 1937-1942 and 1967-1972. Many other states have begun scanning aerial photos, which will be added to our standard selections.

Note: The accuracy of the orthophoto is dependent upon the quality of the image scan and camera calibration data. Some historic aerial photos lack camera calibration data but can still be orthorectified with an accuracy between 2-10 meters.

Example Orthophoto:

In the aerial photograph at left, a pipeline trending southeast to northwest is seen as a curvy line due to distortions caused by the terrain. In the DOQ at right, the distortions have been corrected, and the pipeline is seen in its true state as an almost straight line.
Source: United States Geologic Survey

Request Historic Orthophotos:
To request orthorectified historic aerial photos from the library of scanned aerial photos in Pennsylvania, please provide the following information:

  • USGS topographic map with the area of interest (AOI) outlined
  • Time Period (1937-1942 or 1967-1972)
  • Projection preference (if any)
  • Format (ie. Tiff, JPEG, BMP, etc.)

The requested historic orthophoto will be placed on our FTP server for download or mailed on CD/DVD within 3 to 5 business days.

Orthorectification Cost :
The cost for orthorectifying a scanned aerial photo is $129.

For areas or time periods outside of the available digital library, research and scanning will be additional. Please email us for a quote.