TABLE 3. Block triangulation of Survey Department of Waterstaat 
  
  
  
  
  
  
  
  
  
  
  
; Scale of Number of | Number of 
No. km? area Camera photo strips photo’s Instrum. 
Wild 
1 25 RC-7 1 : 10.000 5 65 A7 
2 33 RC-7 1: 6.000 18 290 C8 
3 70 RC-7 1 : 13.000 6 115 A7 
4 190 RC-7 1 : 10.000 25 390 A7 
5 22 Zeiss 15.000 8 144 1) G8 
2RMK 21 : 18 
6 90 Wild 1 : 10.000 9 140 A7 
RC521 : 18 
  
  
  
  
  
  
  
  
  
  
  
1) 72 stereo-pairs. 
TABLE 3 mentions the 6 blocks on which the Survey Department of the Ministry of 
Transport and Waterstaat has applied aerial triangulation with block adjustment. The 
flightlines are taken parallel to each other. Regarding methods of adjustment of distortion, 
operators, time of relative and absolute orientation, the information given above is also 
valid in this. For 4 of the 6 blocks the adjustment is done according the Schermerhorn 
method, making use of x and y differences in the common points in the lateral overlap 
between strips. In two blocks the Jerie method of adjustment was applied for planimetric 
coordinates with reasonable results. 
Radial triangulation is neither applied for isolated strips nor in block triangulation to 
any extent worth mentioning. 
The application of the digital triangulation with the use of precision stereocomparators 
is being carried out on an experimental basis in cooperation with the I.T.C. There is in 
this service a trend to use this method in future as standard method for aerial triangulation 
because of its economy and perhaps as can be expected under certain conditions also 
because of increased precision. 
II. 5. Aerial triangulation by K.L.M. Aerocarto, Cartographic Section 
In addition to the general remarks made in III. 1., which are also valid for this organiza- 
tion, we can report as follows about its activity. Since 1956 aerial triangulation of single 
strip has only been carried out once, all other aerial triangulations being blocks of several 
strips. The single strip triangulation consisted of 13 strips with a total of 164 models. 
Photographs were taken with Wild RC 5a 9 x 9”, scale of photography 1 : 40.000, flying 
height above sea level 6100 m, longitudinal overlap between 60 and 65%. The strips were 
flown with their axes along a more or less straight part of the rivers to be mapped. 
The aerial triangulation was carried out in the Wild Autograph A 7 applying aero- 
nivellement (bz = 0) and the numerical method of relative orientation. Absolute orienta- 
tion of the first pair was carried out as good as possible on the river. No auxiliary or camera 
orientation equipment was used. Time per model about 80 minutes. 
The grond control in this case consisted partly of an intensive triangulation network 
with numerous good identifiable ground control points which were determined with 
relative mean square errors in x and y of about 0,5 meters. Ground control also consisted 
of astronomical stations with their bases, which were determined for an older aerial survey 
of the whole area. Their relative mean square error in x and y is estimated at about 
1,5 meters. This figure has nothing to do with the precision of the absolute position since 
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