MATHEMATICAL FORMULATION & DIGITAL ANALYSIS 1359 
  
  
  
Fic. 2. Close-range photogrammetry using absolute position controls. 
  
  
Fic. 3. Close-range photogrammetry using distances in object space as 
controls. 
À computer program called SAPGO-A?!, which was developed at the University of Illinois 
at Urbana-Champaign primarily for the purpose of analytical aerotriangulation, can accom- 
modate the wide variety of conditions illustrated in Figures 2 to 6. SAPGO-A is the acronym 
for Simultaneous Adjustment of Photogrammetric and Geodetic Observations— version A. Its 
formulation is based on the principle of observation equations as described in the above 
paragraphs. It has the unique capability of using geodetic measurements as controls in the