, 
\ 
o 
17 
metric means amounts to approx. 30 % since 1968. 
Special Applications of Photogrammetry 
  
At the Royal Institute of Technology (KTH) a number of calibra- 
tions of cameras for special photogrammetry have been performed. 
Among these cameras for special photogrammetry is the Swedish 
Hasselblad MK 70 measuring camera which has been used by NASA in 
the Apollo missions to the moon. The camera has three inter- 
changeable lenses and a reseau plate in the negative plane. 
Electric film feed and the use of 70 mm film makes the camera 
very feasible. The calibrations show that two of the available 
lenses are practically free from radial distortion. The standard 
error of unit weight in the image co-ordinates was about 2-5 
micrometers for all three lenses. This camera can be considered 
as a big step forward and will be a very useful tool for many 
applications of photogrammetry to special purposes. 
Two Hasselblad MK 70 cameras were used by the National Land Sur- 
vey Board.in experimental aerial photography from extremely low 
altitudes, 40-160 metres. The cameras were placed at the ends of 
an 8 meter base mounted under the fuselage of a helicopter in the 
longitudinal direction. The shutters of the cameras could be 
simultaneously triggered electronically. The base on which the 
cameras were mounted was a frame constructed using special 
quality steel. In order to place the two camera axes parallel 
with each other a specially developed method was used. Natural 
vertical lines, such as trees, poles and corners of houses, may 
be used for the orientation of Z-axis of the measuring system 
in relation to the terrain. 
For special studies of vegetation the University of Stockholm 
used an anchored balloon (70 m”) as platform for a Hasselblad 
500 EL camera. For this purpose a remote controlled mechanism for