ii 
  
(49; + 2pp + Dy =. By + Pg Pg) 
N 
pt 
Mu 
SS N 
fp ® Bln Pyar By Dave Ph = By + Pg) 
Koen p, is pat ipe Cespa) 
g 5 4 5 6 
1 
k. = i b= 2D =. 20h ot Du + D. + p.) 
5° Z Py = Pact Pa Dach By ig 
a is the centre angle between the positive x-axis and 
the respective point and p, 1s the measured y-parallax. 
The radial distortion is obtained from the computed 
residual parallaxes as 
ef 
dr = (2) 
cos= 
2 
  
ge 
If b is the base on the image scale, the abscissa of 
the distortion diagram is obtained as 
r = 2b sin 5 (3) 
The radial distortion was determined as the mean value 
of the four determinations, which were obtained for each 
radius, The figures 1 - 3 show the distortion curves and the 
four different determinations of the distortion. For compa- 
rison the distortion curves, given by the manufacturer, the 
Wild Co., are also included on the same diagrams. 
The figures show that there are quite large differences 
between the four individual distortion curves from which 
the average distortion was determined. These variations may 
be caused by accidental errors in the y-parallax measurements 
and by systematic errors of the lenses, the film etc. 
From (2) we obtain the standard error of one determi- 
nation of the distortion & 
RL CREE 
  
  
>>> eee CS mmm E v — 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
tX - 
Iscr ete EE