10 
mittee continues its research work in this expectation. Questions of organi- 
zation also require a universal and thorough investigation. In its report the 
committee proposes an official investigation into production and supply of 
photogrammetrical material in Sweden. 
Research made at the Division of Photogrammetry at the Royal Institute of 
Technology concerning Special Photogrammetry. 
The activity at the Division of Photogrammetry has during the last few 
years to a considerable extent been devoted to special photogrammetry, and 
several new domains of application have been tried. 
The apparatus of the Division includes 
Cameras: 
1 photogrammetric stereo-camera Wild (b = 120 cm), 
1 photogrammetric stereo-camera Wild (b = 40 cm), 
2 stereo-cameras Zeiss of amateur-type for plates size 9X12 cm, 
A number of small cameras of amateur type 
1 phototheodolite Zeiss 13X18 cm, f = 19 cm, 
1 phototheodolite Hugershoff-Heyde 9X12 em f = 12 cm, 
1 phototheodolite Zeiss TAL 6X9 cm, f = 5 cm. 
Plotting instruments: 
1 stereocomparator Zeiss, 
1 autograph A6 Wild, 
1 autograph A4 Wild (police-autograph), 
Stereoscopes, stereomicrometers etc., 
Coordinatographs etc., 
A universal plotting instrument for precisionsworks, A7 Wild, is on order and will pro- 
bably be delivered during 1952. Such an instrument is highly desirable for research 
purposes. 
Testfield for Close-up Equipment. 
For several reasons a special test-field for control of the instruments is 
necessary. The best way of obtaining this is to determine the position of 
a sufficient number of points in space and then take stereoscopic photo- 
graphs of them. At the plotting of such pairs of pictures systematical 
errors are easily found out, and the reasons for them are discovered. 
Furthermore, it is possible to determine the real accuracy after the correc- 
tion of such errors and thus to determine the domain of application of 
the method. 
For the small stereo-cameras a test-field has been arranged in quite a 
large room, where a number of measuring-tapes were suspended from the 
ceiling. (Fig. 1). The measuring-tapes are provided with marks at suitable 
distances from each other, which serve as the real control points. The tapes 
are kept straight and immovable by weights immersed in water. By angle 
nieasurements from three points on a suitable base, the relative positions of 
the points are determined in relation to the cameras. The accuracy of the 
determination of the positions of the marks is sufficient if the mean error 
amounts to some tenths of a mm. Information about the accuracy of each 
point is obtained from supernumerary observations. 
  
  
  
  
  
      
  
  
  
   
  
  
  
  
   
   
   
   
  
  
  
   
  
  
  
   
   
  
    
  
  
  
  
  
  
  
  
   
  
  
  
  
  
  
  
  
  
    
B 
mat 
fect 
A 
lite: 
pos: 
oth 
coa 
fro: 
an 
the 
The 
rac 
to 1 
me 
ma 
tak 
fro