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plotting cameras that have, besides the three usual rotations co, cp, k, also the 
rotation q about the nadiral axis, as in the Nistri Photocartograph mod. V and 
in the Nistri Photomultiplex mod. Dill. The method assumes, firstly, that the 
knowledge of the nadir point is free from error; consequently, to the relative 
orientation of the photogram to be chained to the preceding, there is entrusted 
the determination of only three parameters; the magnitude transport is effected 
according to the classic method. 
He then goes on to consider the character of the errors, in the gyroscopic 
recording of the nadir point, due to the anomalies that the working of the. gyro 
scopes present, even when the supports of these are fixed to the ground, and 
to the accelerations to which the airplane in flight is subjected, accelerations 
that compose themselves to the gravity. He points out that only the curvature 
of the mean course, such as that obtained by uniting the take points with a 
continuous line, introduces a systematic error which is extended to all the chain 
of slight degree, given the flight characteristics, while every other source gives 
place to errors that, considering photogram for photogram, present accidental 
character; so that errors resulting from the recording can be considered acci 
dental. 
Consequently he reconsiders the method of chaining so as to deduce the norms 
that are convenient to follow in the chaining of those photograms, for which the 
error by which the gyroscopic nadir point is affected, is of such an entity as to 
be surely revealed by the relative orientation of the stereogram; in such cases 
the relative orientation must be perfected by eliminating the vertical parallaxes, 
and the gyroscopic recordings are to be used only for the absolute orientation 
of the stereogram; in fact there is to be recognized, in the gyroscopic nadir point 
method, the prerogative to greatly reduce the propagation of the systematic 
rotations about the Y and Z axis in the chains. 
He makes known that the experiments upon the application of the gyroscopic 
nadir point method to spatial aerotriangulation were proposed in 1953 at the 
O. E. E. P. E. (European Organization for the Study of Photogrammetrical Ex 
periments), the organization that in 1954 made the take flights with the OMI 
— Nistri Foma Camera; the material for the execution of the chainings has not 
as yet been distributed. Therefore he makes known only some data taken from 
experiments made at the OMI of Rome, from which there can already be 
foreseen the utility and the practicality of the application of the Nistri method 
of aerotriangulation by gyroscopic nadir point, to aid in the medium and small 
scale surveys made with the use of instruments of second order, and by means 
of the Nistri nadir point Photoprinter — Photorectifier, instrument which will 
be described to the 1st. Commission of the I.S.P., to the chainings and to the 
formation of photoplanes on level grounds. 
Aérocheminement à point nadiral gyroscopique d’après la méthode Nistri 
L’auteur expose la méthode d’enchaînement d’une série de photogrammes, qui portent l’enregistre 
ment du point nadiral respectif d’après la méthode bien connue Nistri, à deux axes primaires gyro- 
scopiques. 
En supposant, tout d’abord, que la connaissance de ce point soit exempte d’erreurs, il en 
considère les règles générales d’utilisation dans un appareil restituteur aérotriangulateur, soit de type 
normal, soit muni tout spécialement de chambres de restitution, disposant de la rotation Q autour 
de l’axe nadiral, en plus des trois rotations courantes co, 90, x. 
Il examine ensuite certaines causes qui portent à des erreurs dans l’enregistrement du point 
gyroscopique, en remarquant que seule la courbure de la route moyenne — telle quelle est obtenue 
en unissant les points de vue avec une ligne continue — peut introduire une erreur systématique 
étendue à toute la chaîne, tandis que toute autre cause ne donne lieu qu’à des erreurs accidentelles, 
ce qui fait que l’on peut considérer accidentelle, d’une façon prédominante, l’erreur de l’enregistre 
ment. 
A la suite de cette constatation, l’auteur déduit les règles à suivre pour les photogrammes de la 
chaîne dans lesquels l’erreur du point nadiral gyroscopique soit assez évidente pour être clairement 
dénoncée par l’orientation relative au photogramme précédent.