184 RECENT DEVELOPMENT OF APPROXIMATE INSTRUMENTS, DISCUSSION
g. Stereometer instruments with other correction devices.
(Stereographometro Nistri, Stereomicrometer Santoni).
I myself have many objections against this classification. I should like to have amend-
ments. A classification on precision, I think is not very practical.
3. Evaluation of instruments of this nature relative to *exact" restitution instruments.
Prof. Gotthardt's publications may be a starting point in this discussion. Related to
this discussion we may deal with the question of the future of approximate instru-
ments. Those who cannot see any future are reminded of the fact that about the
whole U.S.S.R. for instance, was mapped with instruments of this nature.
4. What is the opinion of the panel about using (approximately) rectified photographs
in instruments of this type?
Will it be possible to use also superwide-angle lenses then?
(Question suggested by Mr. E. Santoni.)
Discussion
Mr H. C. ZorN: May 1 first introduce the
members of this panel to you. On my right we
have Mr Baboz; on the left is Mr McMillen
from the United States; and at the end is Mr
Santoni from Italy.
The members of this panel have agreed to
pool the available time for their lectures and 1
will thus give a short review of the contents. I
will try to list out of those papers the main
points of interest about which a discussion may
be necessary.
The papers offered for discussion are, first,
one by Mr Santoni; second, that of Mr Baboz;
then one from Mr McMillen; and another one
has been added, somewhat late, from Mr
Makarovic from Jugoslavia. Is Mr Makarovic
present at this moment? (Mr Makarovic then
joined the members of the panel on the plat-
form.)
My own publication, as it appears in Photo-
grammetria, B, will be integrated in my present
talk. First of all, I would like to say a few words
about Mr Santoni’s paper called, “Le domaine
d’emploi des appareils de restitution non fondés
sur une reconstruction rigoureuse des faisceaux
perspectifs”. In my opinion, this paper belongs
mainly, in fact, to Commission IV because it
deals with the application of instruments more
than with the instruments themselves. However,
there are some points of interest in it. The main
conclusions of Mr Santoni are that instruments
of third order will be used for map revision, not
only of small-scale but also of large-scale maps.
It follows that those instruments will be used
for new map-making, and it may be an idea in
that respect to use rectified photographs. If we
use rectified photographs, then it may also be
possible to use superwide-angle photography,
in those instruments which will not take them
normally, for example the stereomicrometer of
Mr Santoni.
This raises the point that we must have a
rectifier. I think we must have a 1 : 1 rectifier.
Maybe, the big ones can also be used. I do not
know much about the application of that. After
my talk, I should like to put to Mr Santoni the
following question: which rectifier do you
suggest, a telescopic one or the normal one
which we all know?
Mr Santoni wants to use for his rectification
data, given either by solar periscope or aerial
triangulation, so that the ¢ and the c can be
introduced into the rectifier.
Mr Baboz’s paper deals with the Stéréoflex,
and the first statement in his paper is that for
small-scale maps the interpretation of the ter-
rain forms is more important than the metric
value of it. That is a very acceptable statement.
It may be somewhat indefinite, and if there is
time available maybe some of you will want to
comment on this statement. I had hoped to be
able to use a slide of this instrument just to show
you what we are talking about, but apparently
we failed in getting the slide here in time, so I
am afraid you will have to use your imagination.
However, I think the majority of you know the
instrument. The negatives are in a vertical posi-
tion and you have two semi-transparent mirrors
in front of you. You look through and against
those mirrors, so that you see the two photo-
graphs stereoscopically, and at the same time
you see the floating mark on the table just over
the pencil or the connecting point of the pan-
tograph. The main thing you will notice is that
we are using here an affine model, so that means
we have not introduced a proper principal dis-
tance but another distance of about 300 metres,
and that makes that model deformed.
This proportion between the horizontal and
vertical scale can easily be computed, so in
practice this is not a disadvantage, only we
understand that in this instrument also there are
model deformations. At the Institut Géogra-
phique National in Paris this instrument has
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