5 
ACKNOWLEDGEMENTS 
We wish to express our sincere thanks to all cooperative 
photogrammetrists and other interested individuals who 
have contributed to the work upon which this report is 
based. We have attempted to give due credit in the body of 
the report. 
Particularly we wish to mention The Swedish National 
Road Board, The Geographical Survey Office of Sweden 
and the Royal Institute of Technology in Stockholm. 
Financial support has been given by The Swedish Tech 
nical Research Council. 
1. INTRODUCTION 
The main purpose of photogrammetry is to determine 
primarily geometrical data such as size, position, and 
shape of photographed objects and to perform this task 
with sufficient geometrical quality and completeness at a 
minimum of cost and time expenditure. In certain, generally 
very rare cases the highest possible geometrical quality is 
sought after regardless of cost. 
As a rule quality and cost at least approximately are 
proportional and therefore these factors always have to 
be considered in most practical cases. The success of 
photogrammetric work depends very much upon the ratio 
nal planning of the chain of operations, which lead to 
the final results. From the standpoint of the photogram- 
metrist it is of evident importance to know the require 
ments of the final results in order to choose the most 
suitable instrumentation, material, operators and methods. 
The requirements have to be stated by the user of the 
final products, who must be able to determine them, for 
instance with respect to the quality of other operations 
with which the results of the photogrammetric procedure 
are to be combined. It is evidently desired that the errors 
of the photogrammetric data be kept so small that they do 
not increase other errors noticeably. 
The photogrammetrist, in planning the most economical 
combination of material, instrumentation, operators-and 
methods for the purpose mentioned, must evidently know 
the quality of each of the operations which are to be com 
bined in his procedure. The quality of his final results must 
depend upon the quality of each individual operation and 
consequently upon the quality of the material, instrumenta 
tion, operators and methods. Because each individual 
operation plays the role of a link in a chain and every 
camera and instrument has its own characteristics, the 
quality must be individually tested and determined. 
Furthermore, for evident reason there should be a har 
monic relation between the geometrical qualities of the 
individual operations. In order to express numerical quality 
data it is evidently of basic importance that well defined 
concepts and terms be used. Otherwise confusion and 
misunderstandings may be caused and the logical relation 
between quality and economy may be seriously disturbed. 
In other words, for a successful development of photo 
grammetry in or without competition with other techniques 
of measurement it seems necessary that the quality problems 
be carefully treated. The first requirement is of course that 
the concepts and terms for quality are completely clear. 
Up to now, in photogrammetry as well as in other sciences 
of measurement this is not the case. Although consider 
able work has been devoted within I.S.P. to the terminology 
problem for the quality of measurements in photogram 
metry since 1958 at least, the literature of today still shows 
considerable lack of clarity in this respect. Numerous 
examples can easily be found. If the purpose of the quality 
information is to give an approximate expression for the 
quality of a method, of material and instruments, of the 
final results of the photogrammetric procedure a certain 
indistinction of the terminology may not be too serious. 
But if the quality information is to be used for the deter 
mination of tolerances, not to be exceeded, for instance in 
connection with calibrations, or if the figures are to be 
used together with other quality information in laws of 
error propagation it is most important that the quality is 
expressed in clear and well defined concepts and terms. 
These problems are of evident importance for investiga 
tions of the geometrical data upon which photogrammetry 
is founded. So far, the physical determination of the ele 
ments of the interior orientation, partly or completely, of 
photographs and projectors of analogue restitution instru 
ments, including rectifiers, belong to the fundamental 
requirements of photogrammetry. This is equivalent with 
calibration procedures, which for evident reasons must be 
done also under operational conditions. 
Because these problems, according to specified instruc 
tions to the Intercommissional working group for funda 
mental problems, have been treated in particular in this 
working group, the concept of calibration will be discussed 
in this connection. 
According to ordinary definitions (see for instance 
Webster’s dictionary), the word calibrate means “To 
standardize (as a measuring instrument) by determining the 
deviations from standard, so as to ascertain the proper cor 
rection factors”. In the sense of theory of errors, calibra