The residual, errors after this final adjustment showed no signifi 
cant systematic error patterns like the previous adjustments. They 
also indicate that with full compensation for systematic error, the 
AP-2 should he able to compile contours with a C factor in the range 
of C ~ 2500 using materials flown with a 6" focal length camera at 
60°/o forward overlap. 
Summarizing this Test, the analysis of the results of the linear 
adjustment revealed the character of overall model deformation. A 
second degree adjustment removed the gross non-linear systematic 
errors due to other unknown effects such as possible residual earth 
curvature, errors in orientation, etc. Analysis of the results 
of this adjustment indicated some remaining surface deformation of 
unknown origin. 
This remaining error might have been caused by differential film 
shrinkage or other physical defects of the diapositives. The history 
of these plates is unknown. After partial model adjustments were 
performed, residual errors were reduced to approximate randomness. 
These tests indicate the degree of degradation of heighting accuracy 
that can be introduced by the photographic materials themselves over 
and above what is removed in the absolute orientation process. It is 
tests such as these that justify the need for a Black Box capability 
of which more will be said later in this paper. 
11.2 Compilation Tests 
Planimetric capabilities have been tested which show that the 
viewing system is quite adequate for discerning planimetric features 
to within the mensuration capability of the instrument. Contouring 
tests using materials equivalent to those obtained from 6" focal 
length cameras flown vertically with a forward overlap of 6o°/ 0 
have given a spread of C factors from 1000 to 2000. These compared 
quite favorably with similar tests using the same materials on an 
A-7. On the basis of such tests, the conclusion was reached that 
under operational conditions, both instruments were equivalent. 
12. Black Box Tests 
Black Box Tests were designed to test the precision with which 
the Black Box Program could eliminate random non-linear distortions 
in an AP-2 stereo model. The tests performed were: 
a. Test the numerical precision of the Black Box Program 
b. Test the accuracy using real data 
12.1 Numerical Precision Tests 
17