82 
PROCEDURES OPTIMISATION IN THE QUALITY SYSTEM 
V 
G. Bezoari, F. Guzzetti 
Dipartimento I.I.A.R. - Sez. Rilevamento - Politecnico di Milano 
Summary 
The results of procedurea optimisation in the activity of “Gino Cassinis” Laboratory of Politécnico of Milan are 
discribed in this report. The laboratory works into Politécnico of Milan’s Quality Sistem for the determination of 
instrumental standard deviation of teodolites, diastimeters and levels. 
1- Introduction 
This Memorial Meeting organized with sensibility 
by prof. Mussio in memory of Prof. Cunietti gives 
us the possibility to make some considerations on 
the activities that the Survey Department of DIIAR 
(once "Istituto di Topografia, Fotogrammetria e 
Geofisica" headed for many years by prof. Cunietti) 
is carring on. 
The activity related to the Quality System started 
and had its impulse with prof. Cunietti who had a 
deep knowledge of the topographic instruments. 
We have to remember that prof. Cunietti 
suggested to name our Quality System laboratory 
after prof. Gino Cassinis (ISPRS President, Rector 
of the TU of Milano and Major of the same city), 
our distinguished predecessor at the Topography 
Institute as principle of the chair later occupied by 
prof. Cunietti. 
After this right and opportune introduction, we want 
to observe that one of the prerogatives of the 
System is the constant check of the plannings as 
well as the obtained results. That is to say that the 
application of operative methods needs continuous 
checks. 
These checks that are made every half-year often 
lead to the introduction of method variations. 
These variations can be defined as optimisation 
interventions. 
We want to illustrate the modification about the 
taratura of the teodolites until now carried out with 
another procedure that was dated before July 
1997, when the "Gino Cassinis" Quality System 
Laboratory began its activities. 
2 - Procedures 
The measures and calculation procedures have 
been studied so that the errors have no influence 
on the search of precision. 
Tests results are due to casual influences that are 
difficult to analyse: the causes derive from all the 
instrument parts, from the operator and are heavily 
influenced by metereological and illumination 
conditions. 
W'e chose to work on the ground and our 
suggestion is to work in normal, not in extreme 
conditions. 
Working in different conditions it is possible to 
know metereologicai condition influences: This isn’t 
a laboratory goal; so the reccomendation is to work 
during normal (not extreme) condition. 
Using the same procedures with a significant 
number of instruments of the same model 
(minimum 4) it is possible to define the 
characteristics of that instrument model. Also this 
isn’t a goal of laboratory activity. Besides if is 
possible to make this evaluation using all the 
reports result from our activity; in this case the 
results dipend also from the rectified conditions of 
instruments that arrive to the laboratory. 
The DIN 18723 assumes the standard deviation to 
represent the instrument precision. For this reason, 
different series of Ij measures are earned out in 
relation to the kind of instrument; every j serie is 
characterized by a certain number of rij values 
referred to the same largeness (considered 
undipendent). 
The simplest example is the settling of the 
standard deviation of teodolites: once fixed the 
instrument, we define 5 aims sc in a suitable place 
and distance. 
The measure operation can be repeated with the 
strata method, in a quite short time and anyway in 
the same conditions. Every statum str is made by 
5 lectures that determine 4 angles. Since we don't 
know before the angle that we are going to 
measure, to create a ripetition it is necessary to 
make at least two strata; the number of indipendent 
measures rij that we see is: 
rij = (,str - l) • (sc - l) 
This number is made by a serie that has in itself 
the characteristics of repetition but this is up to the 
operator and the weather conditions. Mean square 
errors analisys of the measured values compared 
with mean value constitutes a dispersion index that 
is characteristic of the whole instrument, operator 
and ambience. 
This formula defines the difference of the value: 
where /j is the medium of I values of j serie. 
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