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SUB-COMMISION IV-3
SMALL-SCALE MAPPING
President: Mr T. J. Blachut (Canada); Mr C. Broillet (Europe)
Presentation of the General Report of Sub-Commission IV-3
in the Meeting held on Wednesday, 7th September, 1960
by the President, Mr Blachut
With your permission I will skip my report
on the situation in the “Small-scale Mapping”
during the last four years, because my report
has been published and there is not much new
development. In view of the very short time I
would prefer to describe some of the results of
our experimental work.
I would also prefer to start immediately with
some comments on our experimental work.
However, as it has been stressed, human prob-
lems even in our association should not be for-
gotten and I would like to mention a few facts
which I think are of importance.
First of all, the activity of Sub-Commission
IV-3 has been conducted by myself and I have
been helped by my colleagues, Mr Broillet from
Switzerland, Mr Tewinkel, who conducted in-
dependently the analysis of the accuracy of con-
touring, and by Professor Finsterwalder, who
was kind enough to analyse certain aspects of
small-scale mapping. It is unfortunate that Mr
Tewinkel is not present and so will not be able to
address you. Professor Finsterwalder will say a
few words.
I would like to draw your attention to the
fact that all the reports have been published,
first in the Canadian Surveyor in the May issue
of this year and then they have been distributed
at this Congress.
I should not forget also to mention the
participants, who are, of course, most important
in this kind of work. Judging by the number of
participants and the number of submissions we
have been extremely successful this time and I
would say that the problem of our investigation
work was of interest. Altogether we had 38
submissions from about 28 photogrammetric
centres. It was also the first time that some of
the Asiatic countries participated in this ex-
periment and they produced most encouraging
results; I would like to congratulate them for it.
I will now try to describe very shortly the
aim of our experimental work and the most im-
portant results. It has been established in
Canada, it consisted of one single overlap made
out of the photographs, one to fifty thousand.
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It was the decision of our Commission, ap-
proved at a meeting in Brussels, that we should
restrict our research to limited scope, in order to
be able to answer properly some questions. This
material, a photograph of the test area, has been
prepared very carefully and distributed among
the participants only after all control points and
all control elements have been checked. The
participants were requested to submit the
results, the results have been analysed and sent
again to the participants, so each single partici-
pant had occasion to express his opinion, which
helped us very much to straighten out certain
misunderstandings which always exist and are
very difficult to avoid. After we received the
comments we published the results and they can
be found in the report.
The technical aim of the investigation was
to try to find out the source of systematic errors,
which have been very evident from the first
international mapping experiment. We had pre-
vailing positive and sometimes negative errors
and we did not know from where they came.
Secondly, we hoped again to be able to throw
some light on the efficiency of the certain type
of equipment used and we particularly wanted
to compare an anaglyphic type plotter with
other plotters.
As a result I think we can state that the
photogrammetric accuracy at the present time is
much better than we assume generally under the
condition that we treat properly the photograph-
ic material. By this statement I mean not only
the treatment of the photographs but also proper
plotting procedure on the machines. We found
that the biggest errors were caused not by any
failure of the equipment or of the photographic
material, but just by improper operation.
Secondly, we found out that there were re-
markable, astonishingly high, personal errors
of physiological and probably psychological
character. We carried out quite extensive in-
vestigations which, I think, at least indicate that
there is a necessity for more extensive investiga-
tions in this particular field. According to the
figures, which of course are limited, it seems that
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