Accuracy 
What has been experienced in C&GS [6] may serve as an 
example for purposes of discussion of the accuracy that has 
been obtained with the monocomparaior system. I am sure that 
any one of you can improve on these results. For example, 
the camera was an RC-7 glass plate type with a 10 centimeter 
Aviogon lens. The flight altitude was 900 meters. Nine 
photographs were involved in three strips of three photographs 
each where the overlap was 60% in both directions. The nine 
control points were signalized. Based on four of the control 
points, the standard error space vector for all nine points 
was 3*5 centimeters on the ground or about 0.000 04- of 
the altitude. Thus the standard plate error was about 3*5 
microns including all error sources. The horizontal error 
vector by itself was a little less than 2 centimeters or 
0.000 02 of the altitude, or essentially 1 part in 50,000. 
Block adjustment techniques were applied. The observation 
equations were weighted in such a manner that the standard 
deviation at the control points was essentially equal to the 
standard error known to exist in the classic geodetic opera 
tions as indicated by the geodetic computations. 
This accuracy is very near what is being experienced in 
satellite geodesy. It may be true that this accuracy closely 
approaches the ultimate that can be obtained without some 
major improvement in equipment or techniques, such as an 
increase in image resolution by a factor of ten, together 
with a corresponding improvement in the measuring engine. 
The standard deviation of parallaxes was less than 
3 microns. The standard error of the monocomparator was 
determined through extensive tests to be smaller than one 
micron. One is reminded that the least count of the comparator 
is also one micron. 
The small errors were achieved by virtue of the inherent 
favorable characteristics of analytic photogrammetry. The 
photogramme trie solution is as free as possible from mechanical 
and optic defects and maladjustments of machines and instru 
ments. Corrections for the distortion of the aerial camera 
lens are made to the observed image coordinate values, and 
no other subsequent optical distortion can enter into the 
solution. If film is used in the camera, a correction for 
distortion is administered for each photograph individually. 
The perspective solution, being simply Euclidean geometry 
and classic algebra computed to any desired number of 
significant digits, retains all the inherent accuracy of the 
input data without adding any errors of its own. 
Operation Items 
Essentially all the practical applications of computational 
photogrammetry in the U.S.A. now apply the projective trans 
formation equation popularized by Dr. Schmid: