ANALYTICAL PHOTOGRAMMETRIC INSTRUMENTS 
A 
6 
praxis and research in high precision nu 
merical photogrammetry. 
The field of mono-comparators has done 
somewhat better, in that several commercial 
enterprises have addressed themselves to the 
problem of designing a semi-automatic com 
parator which is particularly adapted to the 
measurement of imagery that is ‘hard’ and 
predictable in form and pattern, like star or 
satellite trail photography. While the image 
sensing techniques are promising, it remains 
to be seen if the measuring accuracy will live 
up to the advertised expectations. 
Papers presented for consideration in the 
field of comparators were: 
1. author: 
title : 
2. author: 
title: 
3. author: 
title : 
4. author: 
title: 
5. author: 
title: 
6. author: 
title: 
Hans G. Beck and Günter Fehlkamm, 
VEB Carl Zeiss, Jena, German Demo 
cratic Republic. 
Ein Koordinatenmessgerät mit Ko 
ordinatenregistrierung “Komess 2” 
(A Coordinate Measurement Instru 
ment with Coordinate-Measurement 
Device—Komess 2). 
J. C. Millard, OPTICAL and Me 
chanical Society, France. 
Experiences with Stereocomparator 
S. O. M. 
Klaus Szangolies, VEB Carl Zeiss, 
Jena, German Democratic Republic. 
Photogrammetrische Registriergeräte 
(Photogrammetric Recording Equip 
ment) 
O. Weibrecht, VEB Carl Zeiss, Jena, 
German Democratic Republic. 
Das Stecometer mit automatisches 
Registriereinrichtung (The Stecom 
eter with Automatic Recording De 
vice). 
T. J. Blachut, National Research 
Council, Ottawa, Canada, Division of 
Applied Physics. 
Mono-measurements in photogram 
metric operations. 
M. Carboneil, IGN, Paris, France. 
Advantages Compares, pour l’Aero- 
triangulation, du Stereocomparator 
S. O. M. et du Stereotopographe 
Poivilliers S. O. M. Type BP équipé 
d’un ENREGISREUR de Coordon 
nées. (Compared Advantages of the 
Stereocomparator S. O. M. and 
the Stereotopograph Poivilliers BP, 
Equipped with a Coordinate Recorder 
for Aerotriangulation Work). 
kamm deals with a modification of the 
Komess jf2-instrument and is concerned with 
the incorporation of semi-automatic registra 
tion equipment for the coordinate measure 
ments. An effort was made to provide an 
economically feasible solution which can be 
attained by a limited amount of modification 
to already existing instruments. 
The comparator works in agreement with 
Abbe’s principle and follows, during the 
registration, a least count of 0.1 micron. The 
overall accuracy of the Komess is given as 
±0.5/1. The semi-automatic registration, 
when compared with a fully automatic read 
out procedure, will increase the duration of 
operation by only 10%. In many respects, 
this instrument fulfills requirements which 
have been discussed earlier. The realization 
of Abbe’s principle, combined with a O.ln 
readout interval and an overall accuracy of 
+ 0.5ju, are features which will in the future 
become more and more significant for preci 
sion photogrammetry. 
The Komess #2, therefore, appears to be an 
instrument which has potential for all preci 
sion photogrammetric projects where the 
mono-plate principle can be applied, espe 
cially for astronomical work and, correspond 
ingly, also for the application of satellite 
photogrammetry for geodetic purposes. 
The introductory sentence, which states 
that numerical photogrammetric evaluation 
methods can only be executed economically 
with the use of mono-comparators, is, how 
ever, open to question. As stated at the end of 
the subject paper, the measuring accuracy 
will ultimately depend on the pointing accu 
racy. In topographic photogrammetry, the 
stereo viewing and, correspondingly, the 
simultaneous measuring of two or more plates 
cannot as yet be replaced by independently 
executed point marking or pricking pro 
cedures, if measurements in the micron region 
are contemplated. This subject will come up 
later in connection with Dr. Weibrecht’s 
paper. 
Three papers deal with comparator-type 
coordinate instruments and/or associated 
registration equipment, while three papers 
address themselves to principal considera 
tions of mono versus stereo measurements 
and/or give results obtained from the nu 
merical treatment of coordinate measure 
ments. 
In particular, the paper by Beck and Fehl- 
The paper by I. C. Millard first discusses 
some tests which were executed to determine 
the overall accuracy of the S.O.M. compara 
tor. The comparator is reported as having a 
standard deviation of ± 2 microns, computed 
from 200 measurements. The main body of 
the paper deals with a series of modifications 
which were designed to reduce recording 
errors of the Ferranti-counters. The changes