4.0 ANALYSIS OF DATA 
4.1 Lens Distortion 
Using a space resection program, the plate co-ordinates were used to 
calculate the lens distortion and centering errors of the final negatives. 
As a glass plate with grid lines on it had been used to hold the original 
negatives flat, these lines were observed using the iens distortion 
program in the MPS and the lens distortion characteristics of the 
Hassablad lens measured. 
Details of the lens distortion of the original aerial camera were supplied 
on a calibration certificate from Wild. 
Graphs of the radial distortion curves for the original lens, for the 
Hassablad lens and for the combined lens system are shown in Figure 1. 
Hassablad Lens 
    
     
  
7 / 
N 
e 
& 
3 Combined Lens 
B System 
6 «ai 
E Aerial Camera 
S 
Oo 
+» 
A d A A 1 
a Por comes 877 Radial Distance 
(mm) 
  
FIGURE 1: Lens Distortion Curve 
It can be seen by inspection that that the results from the space 
resection program are close to the result from summing the lens distortion 
curve from the original aerial camera calibration with the computed curve 
from the Hassablad camera as measured by the MPS. The resuits deteriorate 
towards the edge of the photograph as there are insufficient data points 
in this location. 
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