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gpecifically addressed the possibility of surveying mating faces 
of ship-halves and mathematically predicting their fit. Of 
this it was stated: 
"There is no question photogrammetric 
measurement of mating sections of ship halves 
and: predicting their fit would be productive. 
If such predictions saved even one workday in 
a.large capacity building dock the costs for 
applying photogrammetry would be more than 
offset." 
2. PHOTOGRAMMETRIC TRIANGULATION 
  
2.1 Basic Concepts 
  
A:camera can be likened to a transit orca theodolite 
indthat it: allows one to determine the equivalent of 
horizontal and vertical angles to specific points of 
interest. The camera, however, is different from its 
counterparts in two very unique respects (refer to Figure 
1). First, from any given instrument location (i.e. 
exposure station) all directions to the points of interest 
are recorded instantaneously with a single "click" of the 
shutter. Second, these directions, which are inherent in 
the recorded image of the object photographed, are actually 
calculated in the laboratory, totally removed from the 
environment of the job-site. 
The determination of directions is easily visualized 
by again referring to Figure l. The location (X14, y1j) 
of the image of a point of interest is measured on a 
photograph with the aid of a very precise measuring 
engine. : The focal length (f) of the camera is known 
by laboratory calibration. Together these allow 
calculation of the direction to the point of interest