Photo Interpretation

Photo interpreters can read an aerial photograph like a book, and they employ many skills to help them analyze the terrain they are viewing.

Photomosaics

One method that aerial photo interpreters use to view large regions in one glance is called mosaicking. Several photos of adjacent areas are pieced together like a jigsaw puzzle to present the "big picture".

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Piecing together aerial mosaics at the Training School at Chanute Field, Illinois, in the 1920s.
Courtesy of Defense Visual Information Center

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Laying mosaics at the Photo Interpretation Center on Guadalcanal.Mosaic lines between the photos are clearly evident. Today digital images can be processed by computer to produce smoother image transitions.
Courtesy of Defense Visual Information Center

Stereo Photography

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Stereo photography allows the interpreter to see the ground in three dimensions by viewing overlapping scenes. This stereopticon or "parlor stereoscope" is an example of an early instrument which employed the stereo effect for entertainment.

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To acquire aerial stereo photography a series of overlapping photos must be taken along a designated flight line. So that stereo coverage of an area will be complete, the amount of overlap for each adjacent pair of photos must be greater than 50%.

The Earth in Stereo

Natural and man-made features can be seen in three dimensions with the aid of a stereoscope and two overlapping scenes. With the addition of depth, aerial photos can provide the interpreter with more information on geologic boundaries, terrain characteristics, relative heights, and regional topography.

Anaglyphs

If you have a pair of red/blue glasses you can simulate the 3-D effect of using a stereoscope by viewing these anaglyphs made from aerial photos.

Carquinez Bridge, Calif.

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Sunset Crater, Ariz.

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Mt. Capulin, N.Mex.

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Menan Buttes, Ida.

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The Broad View

The Changing Landscape