stereo- 
of the 
ographs 
through 
d to be 
through 
ry light 
lighted 
ed and 
ve. The 
tudying 
walk. 
m with 
as may 
in such 
tions of 
wellings 
ed with 
je taken 
ers with 
» dimen- 
rface of 
'e deter- 
'alculate 
r under 
  
  
15 
different external circumstances, variations of the thickness connected 
with these circumstances could be determined. The variations were of great 
importance when studying certain medical questions. Special cameras for 
such purposes are under construction. 
To determine the development of swellings in the face a large number 
of patients having undergone tooth operations were phetographed. The 
photographs were taken before and immediately after the operation and 
then once a*day for some time. | 
At the photography the patient was placed in a cephalometer to take 
the same position. in relation to the camera at each exposure (fig. No. 5). 
The sterec-camera Wild (base = 40 cm) was used. Ancillary lenses were 
used to obtain sharp image of objects close to. The distance to the object 
was less than 1 meter. 
  
Fig. 5. Cephalometer arrangement to ensure con- 
stant orientation of the patient's head. 
The plotting was executed in the autograph A6 to the drawing pencil of 
which a planimeter was directly connected. The planimeter was adjusted 
so as to make it possible to read the volume of closed stereoscopic models. 
The volume to be studied was defined by a space angle, a certain plane, 
and the surface of the stereoscopic model. The space angle was defined by 
lines in the plate carrier and the plane roughly perpendieular to the ca- 
mera axes. 
To control the accuracy of this method an object of known volume was 
photographed and was then measured according to the photogrammetric 
method. Furthermore was controlled the accuracy of the fitting in of the 
patient in relation to the camera by placing the patient in the position 
required and taking photographs ten times successively. From the varia- 
tions of the plotting results the accuracy of the fitting in of the patient 
was determined. 
This investigation was made by P. Hjelmstrom with the collaboration of 
the doctors of medicine H. Bjórn and C. Lundquist. The results of the in- 
vestigation are not yet published. 
    
   
   
   
   
   
   
   
   
   
   
    
   
   
   
  
  
  
   
  
   
  
  
  
  
   
  
  
   
  
  
   
   
   
   
    
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