orientation of the middle photograph set equal to the position and orienta 
tion values for the third photo of the previous triplet. Scale transfer is 
affected by equating the X components of the airbase between photos i and j 
of the current triplet with that of photos j and k of the previous triplet. 
Using the above scheme, assembly is accomplished taking advantage of 
the 100% overlap of the photos common to successive triplets without 
sacrificing the rigor of independent relative orientation for each triplet. 
Since triplet assembly takes place as relative orientation and coordinate 
computation proceed through the strip all values for exposure station 
parameters and triplet coordinates are in a common, arbitrary strip 
coordinate system. 
D. TRANSFORMATION AND ADJUSTMENT TO GROUND CONTROL 
The final phase of the computation consists of transforming coordinates 
of all triangulated points from the arbitrary strip system to the desired 
ground coordinate system. This conversion is perfomed using a linear, 
three-dimensional, conformal coordinate transformation with a minimum or 
1* 3 
redundant number of ground control tie points. * This initial step is 
called the preliminary transformation. 
Ground coordinates obtained from the preliminary transformation may be 
sufficiently accurate. If this is the case no further adjustment is 
necessary. Frequently, deformation of the strip, due to random measuring 
errors in plate coordinates, may cause discrepancies of excessive magnitude. 
In this case the preliminary adjustment is followed by a secondary adjustment 
in which a three-dimensional, simultaneous coordinate transformation is 
performed using second degree equations. This method, similar to that proposed 
and tested by Dr. Mikhail * , has been adapted for this procedure. Transfor 
mation and adjustment to ground control completes the aerotriangulation procedure. 
Output consists of coordinates in the desired ground control system for all 
triangulated points