end-
nts.
d to
tru-
the
iphs
| rectifier.
d. I do not
that. After
Santoni the
r do you
iormal one
'ectification
e or aerial
' ( can be
Stéréoflex,
is that for
of the ter-
the metric
statement.
| if there is
vill want to
oped to be
ust to show
apparently
ı time, so I
nagination.
u know the
'rtical posi-
ent mirrors
ind against
two photo-
same time
le just over
of the pan-
tice is that
that means
incipal dis-
300 metres,
d.
izontal and
ited, so in
>, only we
;o there are
it Géogra-
ument has
RECENT DEVELOPMENT OF APPROXIMATE INSTRUMENTS, DISCUSSION 185
been used mainly for a photo scale of 1 : 50,000
and a map scale of 1 : 100,000. It is, therefore,
a reduction, a reduction of two times. The time
needed for the orientation of such a model was
in general thirty minutes, and the output was
about 100 square kilometres per day, that means
about 40 square miles per day.
After this talk, I should like to have answers
to the questions: were those maps compared
with others? Were there interpretation errors?
What do you think is a reasonable ratio between
the image observed, the ocular magnification in
general and the map you are making? I think
that is an important question for accurate
instruments as well as for approximate instru-
ments.
Mr Masson D'Autume and Mr Makarovic gave
answers to the theoretical deformations. They
determined the theoretical deformations which
you get in instruments of this kind. Mr
Makarovic has presented a paper on this subject.
It is rather a complicated paper with a lot of
formulae in it, and I am sorry that I have not
yet had time to check the formulae although I
have no doubt they will be correct. I think it is
good to read Mr Makarovic's conclusion of the
paper, as this contains no formulae at all and
can be read quite easily at a meeting such as
this. The conclusions are as follows. “For a
convenient correction of space model deforma-
tions on instruments of the third order with the
space solution, it is absolutely necessary to con-
sider the elements of external and inner orienta-
tion. Mechanical correctional installations for
these elements are not convenient because we
can place them directly in the instruments. We
can take the element of external orientation from
the space aerial triangulation, the most econom-
ical method of determination of control points.
The instruments of the type Stéréoflex or Multi-
scope have the advantage over the use of recti-
fied photograph on the stereosketchmaster. We
consider the elements of orientation more ex-
actly, and the working method is also shorter."
The next paper on which I should like to
comment is that of Mr McMillen. Mr McMillen
gives a review of the applicability of the approx-
imate instruments in the United States. He is, in
fact, mainly talking about the American approx-
imate instruments, the Stereographometer, the
KEK, the Wernstedt-Mahan plotter, and the
Multiscope.
Mr McMillen states that application for
transfer of interpretation data into maps is very
good, and that the instruments also may be very
good for map revision. However, he is not very
much in favour of new map-making by approx-
imate instruments, and I think it is useful that I
read the conclusion of his paper also: “In
summary, the limited application of third-order
plotters seems to be a matter of simple econom-
ics. The only sources of economy with these
instruments are low first cost and the use of
paper prints instead of glass-diapositives. Over
a long period of use, these economics become
insignificant in comparison to the losses arising
from the lack of ability to produce a better
product. The user soon finds that, by making a
relatively small additional investment (that is, it
is small when amortized over the life of an
instrument) he can provide himself with an
instrument which produces much more satis-
factory results.”
I should now like to say a few words about
my own paper, only the last part of it. I have
made there some suggestions for discussion. I
should like to start with the first question for
discussion, that is the definition which was also
read out by Mr Vanderheyden a few moments
ago, the definition of instruments belonging to
this third order group of instruments. The defi-
nition which we made at the meeting in Brussels
in June 1959 was as follows:
"Restitution instruments, offering the
possibility of continuous tracing of the plani-
metry and altimetry, but not based on a
rigorous (that means geometric exact) recon-
struction of the two perspective bundles of
rays.
| think that is a good definition but last
night, looking over this dgain, I saw one dis-
advantage. Here we have planimetry and alti-
metry. You know the Radial Line Plotter, the
KEK and the Hilger & Watts, do not allow
altimetric plotting, but I think they belong to
this group. Are there any suggestions here to
change the redaction of this sentence so that
tracing of the planimetry and altimetry is pos-
sible? Shall we change that somehow? Are there
any suggestions here or shall we leave it as it is?
Mr M. VANDERHEYDEN: Instead of plani-
metry and altimetry we could say, “planimetry
and/or altimetry”.
Mr H. C. ZORN: Thank you, that is a very
good suggestion. We could also change it by just
removing the word "plotting".
Mr M. VANDERHEYDEN: That is another
solution.
Mr H. C. ZorN: Mr McMillen, have you any
idea in this field?
