, during
d. It is
of this
umental
entation
reocom-
ed at a
ompara-
aissance
| precise
and pa-
order to
nensions
se coor-
7 à con-
tion. No
reasons:
are too
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system
ns that
he loca-
je found
ocedure;
built in
e of the
er. This
t enough
1 the in-
tting the
cial case
rrestrial
were not
‘or these
THE DESIGN OF PHOTOGRAMMETRIC PLOTTERS, HELAVA 119
reasons it was necessary to look for a more general solution which would enable the
relative orientation of a stereopair, and this was found in the double projector by Gasser
(1915). In this connection, it should be mentioned that as early as 1898 Scheimpflug had
experimented with a similar device but his idea was forgotten, probably because its
orientation possibility could be utilized only when the elements of orientation were known.
The Gasser plotter did not achieve great importance until it was revived in an improved
form as the Kelsh Plotter a quater of a century later.
The principle of double projectors was developed to an advanced form in the Bauers-
feld-Zeiss Stereoplanigraph, which was designed during the early 1920's. Since that time
the instrument design has not changed
from the point of view of construction
principles.
The top product of instrumental
Final co-ord design based on the principle of double
Measuring projection, is a first order plotter such
7 as the Stereoplanigraph, A7, Beta 2,
ete. Their functioning is based on a
real physieal projection implemented
by optical or mechanical means. This
projection system may be considered as
an analog computer. In this connection
it is useful to define that computer as
a simulator because the entire process
of determining the object points occurs
Fig. 1b. through a re-establishment of the situ-
ation existing when the photographs
were made. This definition is important because it gives proper emphasis to the very
prominent influence this approach to the principal photogrammetrie problem has had in
the development of photogrammetric instruments for over forty years.
In 1914, W. Sander stated, “Der Stereoautograph ist eine Vorrichtung zur Auflósung
von Gleichungen." (*À stereoplotter is a device to solve equations") [1]. It is easy to see
now that this statement may be considered as the foundation for a further broader ap-
proach which sets the simulation principle in its right perspective as one special solution
and which, when properly extended, leads to the more general concept of an analytical
plotter, where no restriction is made as to the character of the equations. The plotter is
so designed that in principle it is able to utilize any suitable formulation and any suitable
means of computation to derive the required results. The author of this paper was the
first to make the conceptual extension and to show how such a photogrammetric plotter
could be constructed. The success of the instrument is without doubt entirely due to the
availability of electronic means of computation. However, the concept was established
years before its realization became possible. In this way another step forward has been
taken — another door opened. Where we stand today and what may be expected from the
future are the two questions that will now be considered in this paper.
Data flow in a Plotter
Viewing Computer
uOI1DA43SqO
Operator
2. General consideration of the plotting problem.
The photogrammetric plotting operation is basically a data-processing procedure. The
source data is recorded on photographic plates, or a part of it may be given as control
points or as indications obtained from auxiliary instruments. The final data, usually a
map, is obtained by processing the source materia] in a plotting instrument.
The total procedure is composed of a number of individual tasks that may or may
not be separated. One of the tasks that is clearly separable is the determination of the
parameters required for the process. Some of them, such as the focal length of the cam-
