on 
eters 
omated 
to 
of 
ion 
ing 
ck 
iatically 
and 
would consist of a stereocomparatcr interfaced with a general purpose 
  
   
aerotriangulation is usually divided into two phases, the data 
acquisition phase and the dita processing phase. In the data 
acquisition phase, the image coordinates are measured either on a 
single-plate or on a stereoscopic comparator. In the data processing 
phase, computer programs are employed to correct the image coordinates 
for known systematic effects and to perform an analytical triangulation 
solution using the corrected photo-coordinates as input data. 
Unfortunately, with this two phase scheme the quality of the 
image coordinates from the data acquisition phase cannot be determined 
until data processing has been completed. To accommodate this 
problem it is accepted practice to measure more points than are 
actually required for the triangulation solution, anticipating that 
some will prove to have blunders, or to measure an adequate number of 
points and remeasure those which are found to be inconsistent in the 
data processing solutions. Either of these schemes tend to decrease 
the productivity of the mensuration equipment and in addition may 
seriously hinder the planning and scheduling of subsequent map 
production functions. | 
An alternate approach could be envisioned in which the data 
acquisition and data processing are combined to some degree by on- 
line computations. The equipment comprising such an on-line system