Digital Skills Demo – Images

November 8, 2006

Fort Kam Images

Part of my project (described in the October 30th “Prospectus” entry below) involves the manipulation of images, specifically digitizing, editing and aligning old maps with satellite imagery.  I’ve decided to post two of the most significant images to give an idea of what the project involved.  First, I had to download some pdf files of old Coast Artillery maps that were posted by the Coast Defense Study group.  These maps were part of a 1922 survey of US coastal defenses.  They were fairly accurate and detailed maps, showing all significant cultural and geographic features.  Additionally, they were aligned to true north, which would prove to be a big help.  The map I was concerned with came in two sheets of an L-shaped area, so I had to print out the sheets in question, cut-and-paste the aligned sheets, and then re-digitize these by scanning them into a jpeg.  The resultant image is on the first slide of the attached ppt file (see the link above).

The next image is a satellite image of the Fort Kam area, extracted from Google Earth, with the 1922 map superimposed.  I selected the present-day Fort kam area in Google Earth and after making sure that the area imaged was approximately the same as shown on the map, I saved the photo as a jpeg.  I made the white background of the 1922 map transparent and superimposed it over the Google Earth photo.  There were a few cultural features from the 1922 era that still exist today, so I was able to properly size and align the old map over the new photo.  By doing this, I was able to determine where the majority of the old structures once stood.  The composite image is on the second slide of the attached ppt file.

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One Response to “Digital Skills Demo – Images”

  1. Jenny Says:

    I didn’t see this blog post before I wrote my comment on the more recent blog post. Good job on the Google earth work. You should put it on your website, too–the overlay.


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