2 
number of fundamental publications dealing with the methods, means and 
interpretation of instrument tests and including detailed examples, 
stating tolerances and tolerance criteria (e. g. /1/ to /33/). 
In this connection, t■he work of this group is facilitated by the results 
of working group II-l (Hallert) dealing with the "bases of photogramme- 
try, concepts and tolerances". It will not be the task of our working 
group, however, to reconsider the problems studied by the aforemention 
ed group. On the contrary, we shall use the results achieved by working 
group II-l as a basis. 
2) The aim 
Standard tests are designed, by their repeated performance, to give the 
user of a photograrnmetric plotting instrument a clear picture of the 
suitability of his instrument for the work intended. The constancy of 
the adjustment and efficiency of the instrument for the desired purpose 
must be guaranteed with sufficient accuracy and reliability. It is 
therefore the intention of the working group to prepare minimum tests 
which can be performed by any user with the aid of forms and require 
little time and expense. 
Standard tests are to be thorough so as to cover the most important 
errors or changes in the viewing, measuring and output systems. In view 
of the desired simplification and acceleration of the testing procedure, 
integral standard tests may be used, in other words, they need not fur- 
ther explore the different errors and their causes. Since these demands 
are partly contradictory, it will be necessary to find the best possible 
compromise• 
In spite of the intended simplification, however, it will be necessary 
to obtain reproducible results. This means that more or less the same 
result should be obtained if the test is repeated right away. 
Although a test should ideally correspond to the conditions encountered 
T7 
Standard tests therefore differ from other tests, for example ex 
tensive acceptance tests performed before the instrument is employed 
for routine work, or from tests made by the instrument manufacturer 
for calibration and adjustment. They also differ from fundamental 
tests as made with a considerably higher investment of time, equip 
ment and money by instrument manufacturers, university institutes 
and other organizations employing highly qualified personnel, with 
the object of determining the limits of the capability of an instru 
ment. Finally, they differ from comparative or even evaluation tests 
in which special precautions are taken to eliminate ambient influ- 
ences and shortcomings of interpretation to test the performance of 
instruments of different design or manufacture (/28/),