magni- 
errors 
curacy 
lations 
of the 
simple 
metric 
e from 
of the 
ments 
ystems 
ions of 
ematic 
which 
5] and 
ximate 
'e very 
; which 
ness of 
opaga- 
'raphs, 
bsolute 
; if the 
mirror 
on the 
(ast 15 
be ob- 
3 to be 
  
  
  
  
991 191 
992 192 
993 193 
994 194 
  
  
  
  
  
  
Fig. 3. Positions in the projection plane and notations of model points for y-parallax measurements. 
determined, the y-parallaxes in a number of symmetrical points (about 28) upon the fundamental 
circles must be measured in addition. The positions and notations of the points in the model are 
demonstrated in Fig. 3. 
Points 15 and 95 are the principal ones. Point 15 is the origin of the coordinate system of the model. 
For base in, point 15 is referred to the principal point of the left projector, and for base out to the 
prineipal point of the right projector. Points 11, 91, 19 and 99 are the lateral orientation points in 
the ordinary six-point scheme of the relative orientation. The positions of the rest of the points in the 
15-point scheme can be found from Fig. 3. 
Particularly for the determination of the radial distortion it is important that the distance d shall 
be chosen so that the influence of, especially, the radial distortion of the optical system upon the 
y-parallaxes in points 11, 91, 19 and 99 is as small as possible. The necessary data for the determina- 
tion of the most suitable d are obtained from the available distortion curve of the actual optical 
systems. Of course the y-parallaxes in orientation points 11, 91, 19 and 99 due to the distortion of 
the optical system can be numerically corrected in the measured y-parallaxes before further computa- 
tions. The fundamental circles are drawn around points 15 and 95 through points 11—19 and 91— 99 
respectively. The radii are consequently =d. Only if b=d will the circles run through 95 and 15 
respectively. The points upon the circles should be chosen so that the angles between adjacent radii 
are equal. In Fig. 3 the angles are chosen — 12*5,