FURTHER STATISTICAL RESEARCHES ON THE INFLUENCE 
OF GROUND CONTROL ERRORS IN PHOTOGRAMMETRIC 
PLOTTING 
Mario Fondelli 
Among the problems still to be solved, in the field of aerial photogram- 
metric plotting, one of the most important is, without any doubt, the 
problem of the intrinsic accuracy to be requested to control points in 
connection with the different conditions of aerial photography and of 
plotting scale. 
The problem is, of course, very interesting from the technical and scien- 
tific point of view as well as from the economical point of view. In fact 
possible errors in the establishment of control points modify the absolute 
orientation of the plotted models and may alter their shape. From the 
other side, by using control points established in the field with less 
accuracy, it may be possible to get some reductions in the work cost 
with sensible financial advantages. 
À pilot research on the influence of the control point errors on aerial 
photogrammetric plotting was started by Mr. Gian Piero Le Divelec a 
short time before his death. The partial results of this research have 
been the subject of a short paper presented to Commission IV of the 
International Society of Photogrammetry at the Symposium held at 
Prague in 1966 [1]. 
Due to the interest of the said research, we deemed it convenient to 
consider again the data collected at that moment to carry out a more 
complete study through the means offered by the mathematical statistical 
analysis. 
As it is known, the research undertaken by Mr. Le Divelec had the 
main purpose of setting the methodology of statistical researches in this 
field. In fact the precedent experiences had shown what could be the 
probable errors in the photogrammetric plotting when the absolute orien- 
tation was based on control points established in the field with a high 
accuracy [2]. 
To carry out his tests, Mr. Le Divelec had choosen the same model at 
the scale of 1:8000, used by Mr. Sven G. Môller for the preparation of