REPORT OF COMMISSION VII 
GVII-5 
etc. Some of this occurred in organizations where photogrammetric 
mapping and photographic interpretation work were being carried on 
simultaneously over the same area; however, equipment such as stereo 
projection plotters are in use for photographic interpretation work apart 
from topographic map requirements. 
2. Continuing progress was made during the reporting period in improving 
the basic equipment of photographic interpretation. Development effort 
was directed toward designing stereoscopes with improved optics and 
variable magnifications. New monocular magnifiers and new-type measur 
ing scales were developed. 
3. A whole family of supplementary equipment and devices for the photo 
graphic interpreter came into being. Much but not all of the emphasis 
was on inexpensive portable equipment, designed to give rapid solutions 
of photographic interpretation problems with moderate accuracies. 
Fig. 1. This experimental table-top size stereo-projector developed for the U. S. Navy, permits two 
or more viewers to study a stereo-model projected on the ground glass screen. 
SPECIFIC EXAMPLES 
Some specific examples of photographic interpretation equipment use and 
improvement are: 
1. Lens stereoscopes: Several designers worked on the problem of providing 
better optics in the magnification (2 to 3 power) lens stereoscopes; a few models 
were produced. Also several lens stereoscopes (United States) were developed 
in which supplementary lenses could be moved in or out of the optical system, 
to permit a choice of magnification. The increasing employment of aerial 
photographs as field maps resulted in greater use of “field stereoscopes” of 
various types. A stereoscope in use by forest personnel of the Korsnas Com 
pany in Sweden is built in the form of a lightweight aluminum carton, in which 
the photographs are mounted for convenient use in the field. 
2. Mirror Stereoscopes: The scanning-type of mirror stereoscope with vari 
able magnification came into widespread use during the reporting period, thereby 
supplementing the many other excellent types of mirror stereoscope already 
available.