A mechanical (analog) stereoscopic plotter is a precision instrument designed to accurately simulate the projection of a stereomodel formed by two overlapping photographs. The projection is simulated through a complex system of plates, jointed rods, and optical components, which the operator adjusts by turning various knobs and wheels. The instrument has a mechanism which allows the operator to draw a map of the stereomodel by transferring the movements of a tracing stand to an attached plotting table.
FIC_019_01_091.jpg - U.S. Navy Alaskan Aerial Survey 1926, first base site South of KetchikanFrom U.S. Navy Alaskan Aerial Survey 1926-1929, Revillagigedo Island is where Ketchikan is...Full size detail of above photo.
National Archives Catalog: Record Group 57:
Records of the U.S. Geological Survey, 1839 - 2008 Alaskan Aerial Survey Expedition Photographs, 1926 - 1979 A-9: 413-479 - Revillagigedo Island (Revillagigedo Island is where Ketchikan is...)
