ing 
ose 
be 
ach 
ion 
eto 
air 
ht- 
11 
ced 
1ed 
red 
rill 
tt- 
ng 
on 
1C= 
on 
latter omit the location of control points for each picture and resort to the direct 
determination of the ratio settings for the rectifier. An older process of this nature 
which has given satisfactory results in photogrammetric practice (hereinafter 
referred to as the ‘adjustment process’) is the Finnish ‘statoscopic horizon-record 
process’; 
4 more recent one is the ‘displacement method’ developed in the United 
States. The latter is based directly on the results of a mechanical radial triangu- 
lation. 
These considerations permit to evolve the requ 
irements to be met by a rectifier 
which will allow both high-precision rectification according to the point process 
as well as the rapid and efficient application of an adjustment process. In order to 
0 
AN 
PA > 
cep 
E 
= A) 
  
  
   
    
      
     
Fig. 8. Diagram of Rectifier SEG V. Cam inverter 
3 for Newton’s equation; spatial rod 
inverter after Carpentier for fulfilment of 
Scheimpflug principle; automatic vanishing 
point control by computing gear 9. Illumi- 
nation by 2 Fresnel lenses. 
latter requiremen 
the height could be reduced proportional 
the rectifying lens, the effective picture an 
ceeded. As regards the necessary intensity of 
(or copy-board) in visible light, 
higher than those of the adjustment process, 
image points and the control points is an essentia 
-——— 
reduce to a minimum the unpro- 
ductive time required for syste- 
matic trials according to the 
point process the number of 
possible adjustments will have 
to be limited by a mechanical 
vanishing point control. An es- 
sential engineering feature to be 
taken into consideration is that 
the application of the adjust- 
ment processes obviously enlar- 
ges the scope of the rectifier 
from that of a simple project- 
ion unit to that of a plotting 
instrument. The structural ele- 
ments must fulfil a number of 
geometric requirements in re- 
producible manner. As far as 
optical and illuminating pro- 
blems are concerned, it must be 
taken into consideration that 
the improved image quality of 
modern survey lenses permits to 
take aerial photographs on 
scales smaller than those used 
previously. Every effort should 
therefore be made to increase 
the power of definition of the 
rectifier lens and to enlarge the 
range of magnification. The 
t is limited by the structural height of the instrument. Although 
to a reduction of the focal length of 
gle of the objective would soon be ex- 
illumination on the projection table 
the requirements of the point process are much 
for the coincidence of projected 
| condition. The main problem 
13