Several articles recently have mentioned offset photo's and matching points.
In the early 90's several aerospace companies used a system for
photogramatry. This system had a special large format camera with high
contrast film, ring flashes and reflective glass micro-spheres. An
automated reader located the center of the back reflection from each sphere
on the films and a computer program converted this data to 3D coordinates.
On objects about 12 feet across I saw data with accuracies of better than
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