Lm. 
À more vocal interest on the part of photogrammetrists in the use of 
colour photographs could perhaps prompt the photographic industry to solve the 
question of colour diapositives and thus master one of the main difficulties in 
using colour photographs. 
USQ-28 Mapping System 
Of considerable interest in this discussion is the mapping system 
recently revealed by the U.3. Air Force. The news release referred to the 
photographic part alone which obviously consititutes the core of the system. 
Once the photographic material with accompanying auxiliary data is obtained, 
the actual mapping can be done by using a combination of more or less conven- 
tional procedures. 
The system, called the USQ-28 Aerial Electro-Photo Mapping System, 
has been assembled by Kollsman Instrument Corporation. It consists of very 
precise inertial systems used for navigation, stabilization and precise recording 
of the verticality of the aerial camera, an aerial camera equipped with a 
projected, réseau grid of 5 cm spacing, airborne profile equipment of the type 
initially developed by the National Research Council of Canada and the Shiran 
distance measuring system, including supporting field stations. The airborne 
components are built into a four-engine jet aircraft capable of cruising at 
high altitudes at the speed of about 900 km/hr. On board, a computer correlates 
and processes various information, some of which is used to update the output 
from specific subsystems and thus improve the accuracy of the final auxiliary 
data. 
Although the individual components of the system are known and have 
been used on various occasions, it is the first time that an effort has been 
made to evolve such a complete system. It would also appear that no effort and 
money were spared (each aircraft with the support equipment costs approximately 
twenty-five million dollars or over 100 millions Swiss Francsi) to assure the 
possible performance and to optimize the whole system. 
Some of the performances are very impressive. For instance, it is 
claimed that the information on the tip and tilt of the camera can be obtained 
with an absolute accuracy of within 30". This is possible because the most 
advanced technology available at present in the field has been utilized. 
Electronic distance measurements (Shiran) to known ground stations are used to 
locate the aircraft's position and, by providing the corresponding verticality 
data, to determine also nadir points with an overall ground position accuracy 
of + lh m. Maximum range to the ground stations is about 700 km. The airborne 
profile recorder supplies elevations above sea level with an overall accuracy 
of * 3m. In addition to the graphical record, the numerical records of 0.6 m 
resolution are available. The range of the profile recorder is quoted as being 
from h,500 m to 15,000 m. 
The inertial navigational system helps to obtain very precise photo- 
graphic coverage. To control the geometric accuracy of photographs, the KC-6A 
camera, with 5 cm-wide mesh réseau, is used. The réseau is projected from 
behind, from the suction platen. The colour corrected lens, Geacon IV, f = 150 
mm, Er favorable distortion characteristics (radial distortion below 8 
microns). 
From the sparse information available so far, several details of the 
System are obscure. This is, however, of secondary importance. It is essential 
to realize that the purpose of the system, which seems to be achieved, is to 
supply enough information so that the actual plotting of map manuscripts can be 
started immediately without provision of external control established by ground 
surveying and without previous aerial triangulation. The precise location of 
camera stations and nadir points, rigidly controlled tilt and tip of photographs,