he 
he 
I: 
PRESENTATION OF THE GENERAL REPORT OF SUB-COMM IV-3 159 
eine nähere Beschreibung, Charakterisierung 
dieses Gebietes; das liegt in Renfrew, in Kanada, 
und die Bearbeiter waren von der ganzen Welt. 
Die kannten dieses Gebiet überhaupt nicht, und 
es wäre sehr wichtig gewesen, wie ich das jetzt 
ganz kurz gesagt habe, diese Gegend etwas zu 
charakterisieren, besonders auch hinsichtlich 
des Waldes, der ja zum Teil etwas Schwierig- 
keiten bereitete, wie und ob man den wieder- 
geben soll. Dann auch die Landnutzung, das 
ist eine landwirtschaftliche Nutzung aber sehr 
typischer Art, und es wäre sehr interessant ge- 
wesen und hätte einem auch manchen Fehler 
erspart, wenn man da etwas Näheres gehört 
hätte. Und dann auch noch ein Hinweis darauf, 
was man in einer Auswertung erster Ordnung, 
und was man in einer Auswertung zweiter Ord- 
nung bringen soll. In einer Auswertung zweiter 
Ordnung wird man Verschiedenes weglassen 
können, aber was kann und soll man weglassen, 
was würde einem nicht als Fehler angerechnet. 
Also das wäre auch ganz wichtig gewesen. Und 
ich möchte nun schliessen, weil die Zeit schon 
sehr fortgeschritten ist, noch mit einer An- 
regung. 
Sie haben gesehen, ich habe hier das Bild 
etwas charakterisiert und sagen wir, vielleicht 
eine Art Interpretation dieser Landschaft ge- 
geben aber nicht eine solche, wie sie in der 
Kommission VII angewendet wird, sondern im 
Hinblick auf unsere topographischen Zwecke 
und Notwendigkeiten. Und ich glaube, man soll- 
te da einen Abschnitt wenigstens bringen in 
einem Buch über Photo-Interpretation, und wir 
sollten uns überlegen, was wir von einer solchen 
Photo-Interpretation für topographische Zwecke 
für Nutzen haben. — Also damit darf ich schlies- 
sen. Ich danke sehr. 
Continuation of the Presentation of the General Report 
in the Meeting held on Thursday, 15th September, 1960 
by the President, Mr Blachut 
I have had occasion already to present the 
results of our experimental work, and we should 
start the discussion. I do not know if there are 
any questions or not, but maybe it would be 
practical just to refresh your memories a little 
as to the most important results so that I shall 
not repeat what we did but will just quote the 
conclusions reached from the experimental 
work, and describe why we reached such con- 
clusions. Of course, if there were to be any 
questions and discussion it would be very nice. 
As you will remember, the experimental 
work has been carried out on a single stereo- 
plotter flown over the test area which was estab- 
lished for this particular purpose. I should like 
to add that as far as the scope of the experiment- 
ing is concerned, it was a decision of the special 
meeting in Brussels. There may be different 
points of view as to whether we did right or not, 
personally I think it was an excellent idea that 
we decided to limit the scope of our experi- 
mental work. As you will remember, four years 
ago we had much larger projects and so we left 
it to our participants to choose the type of pho- 
tographs, equipment, scales, ground control, and 
so on. As a result, it was extremely difficult to 
reach any conclusion. 
This time, because we have used exactly the 
same — one stereoplotter and each participant 
used identical ground control points — all the 
information was identical and it was much easier 
to reach certain conclusions. 
These conclusions are as follows: the most 
serious elevation errors encountered in photo- 
grammetric mapping seem to have their origin 
in corrected procedures rather than in photo- 
graphic material. That is a very important re- 
cognition, and it is exceedingly encouraging. It 
proves that present photogrammetric equipment 
is of very high quality, and if the user of the 
photogrammetric material and equipment pro- 
ceeds properly we may be sure that the results 
will be very good. 
Of course, we have been using a single pho- 
tograph to start with, which is not a large statis- 
tical piece of material, so to speak. However, we 
produced in addition about 25 independent 
stereo-opers over exactly the same test area and 
we tested at the National Research Council all 
the stereo-opers in order to find out whether 
photographs made in entirety in day and under 
different conditions are of the same quality or 
not, and we could not find any large deviations. 
The second conclusion is that unfortunately 
so far there have not been any devices which 
would permit of correction for earth curvature 
in small-scale mapping. That is obviously one 
source of error, and I think it is one of the 
results of such investigations that the manufac- 
turers of the equipment pay more attention to 
our requirements. 
Again, I think the next conclusion is quite 
novel and very important: that human factors 
are greatly responsible for appreciable errors 
which may have a systematic error. We analysed 
this question and there are surprising results. 
TY 
  
  
  
  
dee —