al 
  
Figure 5. Distortions of a series of planes in the optical 
   
model - in positions similar to architectural surfaces - due 
to uncorrected w, in the exterior orientation. 
The adjustment procedure which isolated radial error and allowed significant measurement 
e © of parallaxes at points of actual structural movement depended upon the use of the tangential 
X components only [3] of the measured coordinate parallaxes px and py. (In another context this 
can be described as adjustment on the radial angles outwards from the fiducial centers to the 
image points - see Figure 9). The adjustment procedure was independent of the radial components 
7