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8 
include the reading of co-ordinates. As a check on errors the readings must be 
by different observers. This process is more time consuming than triangulatio 
order plotting machine. 
Made twice 
N In à fist. 
What is needed to improve the situation is a stereocomparator in Which 
corresponding points throughout a model can be accomplished simply and fast, The photo 
graph coordinates should be automatically recorded, preferably on punched Cards or i 
tape. They are then ready for use on the electronic computer, free from reading ang come 
putation errors. 
The second part of the operations consists in the computation on the electronic Compu- 
ter. À tape is read into the machine that contains all the instructions to correct the plate 
co-ordinates, to compute the relative orientation, the scaling, the computation of strip 
co-ordinates and the transformation to map co-ordinates. These instructions are stored in 
the machine and are there ready for use on any strip of photographs. The plate co. 
ordinates and other relevant data are then read in, the machine goes through the computa- 
tions, prints out the results and is ready for the next strip. 
Ferut is a medium fast electronic computer. Additions and subtractions take about 
two milliseconds, multiplications about three milliseconds. A division takes about one tenth 
of a second. The time required to solve five linear equations is about one and a half seconds, 
In the second example, where up to 15 points were measured per model and each re 
orientation was adjusted with 9 points, the average computation time per model was about 
12 seconds. The final run on the machine, after the plate co-ordinates had been correcte] 
for errors, took 43 minutes. This consisted of 8 minutes to read in the instructions, 51, 
minutes to read in the co-ordinates, 6 1/, minutes to perform the computations and 2 
minutes to punch out the computed map co-ordinates and the remaining parallaxes, At 9 
cost of $80.00 an hour this amounts to $34.40. Using a faster electronic computer this 
can be considerably reduced. 
From the foregoing it may be concluded that once suitable Stereocomparators are 
available for the measurement of plate co-ordinates analytical triangulation will be supe- 
rior to triangulation on first-order plotting machines as far as accuracy, speed and cost 
are concerned. This will also apply when the airborne method of aerial triangulation is 
used in the adjustment. It may therefore be expected that eventually analytical triangula- 
tion will become the most widely used method of accurate aerial triangulation, 
pointing at 
lative 
    
  
    
  
   
   
    
  
  
  
   
    
   
   
  
  
  
   
  
   
  
  
  
   
  
  
  
  
  
  
  
   
   
  
  
Fe" 
0.2.