EEE NETTE 
  
  
  
Accuracy 
With accuracy as the essential question in point, it has 
been decided to adopt two different procedures: 
1 - the systems are tested following the instructions 
supplied by the manufacturer and using their hard- 
ware and software; 
2 - some of the components of the various systems are 
varied to control their influence on the final result. In 
both cases only the marked targets have been used to 
minimize the errors of collimation. 
Evaluation of accuracy (according to the instructions 
of the manufacturer) 
The first case tends to reproduce the situation with 
which the generic user who acquires the system is 
confronted. The attempt has been made to use the 
system to the best of its possibilities, following the in- 
structions of the manufacturer. This means that the 
camera, the digitizer and the software are those sup- 
plied by the company as the format of the 
photographic enlargement is the one suggested. The 
orientation operations were homogenized and 
optimized to obtain residuals of similar order of unit; 
the same control points were used for all systems in 
such a way as to avoid introduction of errors from 
topography. The comparison of the different 
orientation systems was made through the residual 
errors of the coordinates of the control points, this 
being the sole comparable results of the various 
systems. 
The restitution was done by taking five different read- 
ings of each point in order to eliminate eventual gross 
error. The accuracy of the restitution of the points was 
determined by comparing the coordinates taken 
photogrammetrically with those taken in topographi- 
cal survey. 
We are completing these experiments and the results 
will be published as soon as possible. 
Evaluation of accuracy (with comparable criteria) 
To carry out the various conditions of homogeneity 
with which were compared the different systems, one 
proceeds to evaluate the elements that, in non-stereo- 
scopic photogrammetric procedure, greatly influence 
accuracy of end results. 
These elements are: 
a - the camera and the distorsions of the used lens; 
b - the dimension of the film and the scale of the pho- 
tograph; 
c - the enlargement of the print used for the restitu- 
tion; 
d - the number of crosses on the reseau; 
e - the quality of the digitizer with which can be com- 
pared: 
- the lenght of the minimum increment; 
- the quality of the cursor (lighting fittings, crosshairs 
dimension, lens magnification); 
- the number of points used for orientation; 
- the number of prints used for restitution. 
Tests will be made on the various parameters to check 
their influence on the system. 
The applicability of different procedures and tech- 
niques of survey are going to be referred also to other 
factors such as cost, technical staff, time required. 
  
  
  
  
  
Fig. 6 
The four photographic models taken with the Galileo Veroplast camera. 
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