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EUM CIE
LATEST NEWS ON PHOTOGRAMMETRIC INSTRUMENTS
IN GERMANY
by K. Scawipersky, Oberkochen, Germany.
The following report proposes to outline the stage of development of photo-
grammetric instruments reached in 1952 after the reconstruction of the Zeiss
Works in Western Germany. It will deal with the latest C 8 model of the stereo-
planigraph put on the market by Zeiss-Aerotopograph, as well as with a new
model of the slotting equipment for mechanical radial triangulation. This instru-
ment had already been developed at Jena and has now been designated ,,Radial
Secator” (from the Latin “secare — to cut”). A new simple 3rd-order plotting
instrument, the Stereotop, has been designed on the basic principles of the mirror
stereoscope. Furthermore a completely automatic rectifier, known as the SEG V
has been made. Work on new survey cameras is making satisfactory progress.
However, no results can be published at this early date. The paper of Dr. Richter,
which is published elsewhere in this magazine, shows that starting from the well-
known Topogon lens it has now been possible to compute a new lens of highest
performance with a picture angle of 668, the T’opar 1:4, which, at considerably
increased resolving power, is practically completely free from distorition:
Series production of this new lens will be favourably affected by the fact that
the properties and characteristics of the Topogon are well-known from long-time
experience.
1) The new Model C8 Stereoplanigrapb.
First-order stereo-plotting instruments seem to be developing asymptotically
toward a stage beyond which an appreciable increase of the accuracy cannot be
obtained with the means available at this writing. This statement applies at least
to all instruments which reproduce the surveying process geometrically, either in
space or sectional planes and either by optical or mechanical projection systems.
On instruments with mechanical projection, the inevitable bending of the guide
rods as well as the resistance to friction which varies under the influence of dust
and changing temperatures, present particular difficulties. These require the
provision of air-conditioned plotting rooms of the type utilized for precision
measurement laboratories. However, even the instruments with optical projection
systems depend on the quality of precision ball bearings and spindles which can
hardly be increased, on inevitable optical residual errors etc.
An entirely new solution — at least for the determination of the coordinates
of discrete points — suggests the determination of the image coordinates in two
stereoscopic pictures with a maximum of accuracy, and the replacement of pro-
jection by a process which eliminates the loss of accuracy, that is: the arithmetical
method. This proposal seems to bring us back to the stage attained already 50
years ago. However, in our days, solutions of this nature have again become possible
with the aid of program-controlled calculating machines. Further investigations
will have to determine whether modern electronic computing machines will be
able to provide technically and economically satisfactory solutions.
Preparatory computations of the author performed with a Z 4 computing
machine of ZUSE, will be referred to later on. This machine, which is set up at
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