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/),