More Roots of Photogrammetry

The blog Modern Mechanix offers another glimpse at the history of photogrammetry today with a scan from the May, 1939, edition of Popular Science. This is the same blog that gave us a glimpse of terrestrial photography-based surveying earlier this month.

The article, Flying Cameras Map America for War, takes a look at the whole process, including collecting imagery from the belly of a military plane, survey parties recording reference points, and stereoscopic photogrammetry back at the base.

The statement of purpose that opens the article feels oddly familiar to a 21st-century geospatial data coordinator:

From aerial photographs snapped by giant bombers soaring four miles above the earth, U. S. Army engineers are compiling maps that will serve as eyes for our armed forces if they ever have to wage a defensive war on American soil.

The image above is a reproduction of "a stereoscopic image of the kind produced by the multiplex aeroprojector used by U. S. Army engineers in making contour maps from aerial photographs." The image at right is an illustration of how one might make sense of "this seemingly meaningless blur of colored lines" to create a topographic map.

I don't think the second image is an actual illustration of a U.S. Army engineer.