Jim Burt, Jeremy White, and A-Xing Zhu of the Geography Department at the University of Wisconsin - Madison have posted an online version of their AAG presentation. The abstract makes it seems absolutely fascinating to those who wish to view old maps.
As part of the new National Map the United States Geological Survey intends to provide digital images of all its historical topographic quadrangles. Users will have access to 180,000 7.5 minute (1:24000) quadrangles and another 120,000 maps at other scales. Contractors are creating these images by scanning paper maps at resolutions of 500-600 dots per inch. Thus the scans are essentially perfect facsimiles of the existing printed archive.
Full utility of the scanned images requires that they be "georeferenced", that is, the images must be tied to a known coordinate system. For example, without georeferencing there would be no way to overlay the maps on other layers comprising the National Map, nor would it be possible to assemble a seamless image from adjoining scans.
Existing georeferencing software employs what is essentially a manual procedure requiring users to digitize known locations on the screen and enter text in dialog boxes. At about 20 minutes per scan, more than 45 person-years would be needed to georeference the entire set of scanned images. This far exceeds available resources.
Our project aims to replace the manual process with an automated procedure that can process large numbers of scans with no operator supervision.