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further explanation is necessary since this has been indicated already in the part III. 1 
of this chapter. 
III. 4. Aerial triangulation in the Survey Department of the Ministry of Transport and Waterstaat 
Starting with the triangulation of strips as indicated in the reports of the various Nether- 
lands services we find first the Survey Department of Rijkswaterstaat. 
  
  
  
  
TABLE 2 
Characteristics of the flight, cameras employed, etc.: 
Triang. 
Conor Photoxcole Flying height Number of Length instr. 
(meters) strips in km 
Wild RC 7 
Jdem 1: 4.000 680 81 260 
glassplates 1 :-. 5.000 850 71 270 
14 x 14 1: 6.000 1.020 88 274 
147.000 1.190 22 100 
1340 7.500 1.275 4 20 A7 
1. 8.000 1.360 20 98 
1 : 10.000 1.700 11 47 
1 : 14.000 2.380 1 6 
1 : 20.000 3.400 7 36 
Zeiss 2RMK 
21:18X18 1: 4.000 840 9 30 C8 
films 1: 5.000 1.050 4 10 C8 
(convergent) 1: 6.000 1.200 11 30 C8 
327 1.181 
  
  
  
  
  
  
  
  
  
TABLE 2 gives the list of the various details showing a total of 327 strips with a length 
of 1181 km. The flight lines are projected and plotted on topographical maps in the scale 
1 : 25.000, accounting for a flight line deviation of plus or minus 159, of the width of the 
strip. The direction of the flight lines is in general parallel to the main axis of the area to 
be plotted. The longitudinal overlap is between 55 and 6595. Regarding inner orientation 
it can be stated that, when adjusting the photograph in the projectors, irregularity of 
distortion is adjusted and averaged on the collimator marks. If these irregularities are too 
large the operator is warned for irregular image distortion and if necessary he may reject 
the material. 
For ground control points, signalized points are used, marked with bone white circular 
metal disks with a diameter between 25 and 50 cm depending on the scale of photography. 
In some cases topographical points of sharp definition are also used. There are in general 
two ground control points in each 4th to 6th photopair on either side of the flightline. 
The operators worked in this service in 7 hours shifts, from 7 a.m. to 14 p.m. and 14 p.m. 
to 21 p.m. including half an hour rest. The time required for bridging depends on the 
total number of points to be measured, on the methods of signalising and the type of 
terrain and varies between one and two hours per model. 
Regarding computation and determination of coordinates this service mentions as 
method of adjustment that of Schermerhorn of 1940. Consequently my conclusion is, 
that most of this aerial triangulation is not dealing with isolated strips but also with blocks 
on which a rather primitive method of block adjustment is applied. 
15