196 CARTES A PETITES ECHELLES, DISCUSSION
la méme que l'échelle de l'édition, mais la partie
la plus controversée est le choix de l'appareil de
restitution. Je crois que la remarque de Mon-
sieur Hoffmann est intéressante dans ce sens
qu'il est absolument nécessaire d'utiliser des
appareils oü le constructeur n'a pas renoncé à
la reconstitution des faisceaux perspectifs. Il est
nécessaire que le restituteur ait une vue correcte
et aussi large que possible de son terrain. Je
crois en effet qu'en particulier dans les appareils
de troisiéme ordre il faut distinguer ceux oü il
y a simplement des calculateurs et ceux oü les
simplifications ne résultent d'hypothéses géné-
ralement admises. Est-ce que sur ce sujet
quelqu'un voudrait intervenir?
Prof A. BRANDENBERGER: Concerning the
use of the type of plotting instruments for small-
scale mapping, I should like to give the following
remarks. In my opinion, in most cases second
order instruments — or even third order in-
struments — would be sufficient. First order
stereo plotting instruments should be used only
for aerial triangulation purposes, and as a
matter of fact not as a rule for small-scale
mapping.
With regard to the attainable maximum fly-
ing height, one can hardly fly higher than about
ten thousand metres above ground. This means
that in a stereo ploting instrument the model
scale will be larger than the mapping scale,
therefore the model errors will be considerably
reduced on the compilation sheet. This leads to
the conclusion that stereo plotting instruments of
highest accuracy, such as first order instruments,
will not be necessary to plot maps in scales
1: 100,000 and smaller. It is, however, nec-
essary in using second order instruments — or
even third order instruments — that the models
have sufficient sharpness, and I am not con-
vinced that, for instance, stereo plotting in-
struments based on the anaglyphic system might
always reach or fulfil this condition.
That is all I have to say here. The time is al-
ready very much advanced and it might be that
some other speakers would like to make some
remarks.
