This project involves the digital restoration and geo-coding of historic Hall County, GA air-photos. The air-photos are from the US Army Corp of Engineers (USACE) Lake Lanier in 1957 and two groups of photos from the National Resource Conservation Service (NRCS), Hall County from 1955 and 1980.  These images portray the land use – land cover (LULC) before Lake Lanier was created and directly thereafter in 1957 and 1980.

To start this process all images have to be digitized using a photogrammetric quality scanner.  The second step is geo-coding the images.  Geo-coding is the process of putting X, Y coordinates a digitized photo to assign geographic coordinates to each pixel in the image.  The geo-coded image can then be displayed in mapping software.  After geo-coding, the photos are then processed into a photo mosaic.  The image brightness histograms were matched To equalize the illumination of the images in the seamless mosaic.  The final step is the Ortho-rectification of this image mosaic, which removes any image distortion due to the terrain relief.  This process adds the Z coordinate which represents elevation at each pixel. Adding the X, Y and Z coordinates to this image mosaic produces an accurate image map that can be used for several different GIS applications. This image mosaic can be used for historical, LULC change, geomorphologic and ecological projects. The techniques used and challenges encountered in this project will be discussed. It was also made possible through grants received from Georgia View

For Details click "Historical Hall County, GA Photo Restoration and Ortho-Rectification: Process and Use 2009"