175 
Chapter VI 
D) SHORT ACCOUNT OF SOME PROBLEMS OF GENERAL 
CHARACTER 
by 
Mariano Cunietti, Secretary of the Group. 
1 - INFLUENCE OF THE SYSTEMATIC ERRORS 
The preceding paragraphs contain all the elements necessary, in our opinion, 
for an analysis of merit of the results. However, we think it useful to hint at and, 
if possible, to begin the solution of two very important problems: 
a) the examination of the influence of the systematic errors due to the photo 
graphic material in the execution of the blocks; 
b) the investigation of the possibility of deducing information on the absolute 
overall accuracy of the block itself, from the intrinsic and relative data on the plotting 
accuracy and from the discrepancies of the ground points used for the adjustment 
of the blocks. 
One of the merits of the collective research organized by the I.S.P. is, in our 
opinion, the possibility of an analysis of an eventual systematic behaviour of the results 
of the blocks, dependent on systematic errors of the photographic material. 
The material for this preliminary analysis is given to us by two groups of tests: 
tests 1, 5 and 8 carried out by the N.R.C. of Ottawa on photographic material obtained 
by camera Wild RC7, and tests 13, 14 and 15 carried out by the I.G.N. of Paris on 
photographic material obtained by camera SOM. 
Within each one of these two groups of tests, the measurements have been exe 
cuted according to different procedures and measuring instruments, but by adjusting 
the results obtained by the same procedures and on the same points. Therefore, 
the three tests of each group are independent but homogeneous. Tests 17 and 18 
are obtained on Wild photographic material but by a different method of adjustment 
and for a different number of points used for adjustment. The homogeneity necessary 
to make the systematic errors evident fails in this case. The same is true for test 19 
carried out on SOM material and for tests 16 and 20 carried out on Zeiss material. 
In order to make the systematic errors evident, we used the means M computed 
as shown in chapter VIB) written on a planimetric plot of “Massif Central” polygon. 
The eventual systematic influence of the errors due to the original photographic