Nadiral Point Gyroscopic Aerial Triangulation According 
to the Nistri Method. 
ESENTED TO THE III COMMISSION OF THE INTERNATIONAL 
PHOTOGRAMMETRY AT ITS VIII CONGRESS IN STOCKHOLM 
by 
Dr. UGO BARTORELLI 
4 PAPER PR 
SOCIETY OF 
Assistant in the Geodesy and Topography Institute of the Engineering Faculty of the 
University of Rome. Advisor to the 'Ottico Meccanica Italiana (OMI)" of Rome. 
There was presented at the previous Congress in Washington !) the Nistri method for 
weording the nadiral point on every photograph, by means of the information supplied, 
i the time of exposure, by the rotations, with respect to the camera, of the primary axes 
jo gyroscopes equipped with erectors; these axes are perpendicular to each other and 
parallel respectively to those which identify the principal point on the plane of the 
hotographs. 
Today this recording system can be used on all the FOMA-Nistri take cameras 
nanufactured by the “Ottico Meccanica Italiana" of Rome. 
As to the characteristics of the functioning of the gyroscopes designed for this 
mticular use, these were reported to Commission I ?); the purpose of this present paper 
that of explaining the applications to aerial triangulation and the related methods of 
meration that derive from the use of the gyroscopic nadiral point. As a principle, we 
will consider this free of errors; in the photographs to be used in the plotters, we find it 
dready created, in its position, by a pricking, made by a special “pricker” in relation to 
the projection of two indices projected by the gyroscopes. 
As to the method of operation for any air triangulation plotter whatsoever, we give 
here the procedure for chaining any intermediate photograph 7+ 1 to its immediate 
peleeessor ?, already absolutely oriented. It is necessary to know the position of the 
mürof each camera in the plotter; this corresponds to determined readings of the co- 
ndinates X and Y of the co-ordinatometer, as given by the conditions of adjustment of 
fie instrument. The orientation of the photograph 24-1 is achieved making use of the fact 
lat, the nadiral point known, there remains only one condition of liberty to the camera, 
tis being the rotation about the nadiral axis of the camera itself. Therefore, when the 
measuring mark is put on the nadir of the projector containing the photograph 4 + 1, 
mnipulating its »” and ¢” controls, the pricked gyroscopic nadiral point of i +1 is 
bought into collimation with the measuring mark. Thus, with the model (à, à + 1) under 
mmination, the parallax is cleared in a point close to the principal point of à + 1, moving 
M with this operation the Y co-ordinate of the nadiral point has undergone the same 
nriation given to [m and thus the gyroscopic nadiral point continues to be projected 
urrectly on the nadir. Next to be considered is a point of the model at the edge of photo- 
faph i+ 1 near to the corresponding one of the principal point of photogram i; the 
Fparallax is cleared by means of the rotation k”. With this the gyroscopic nadiral point 
fitl generally will be off collimation with the respective nadir, but only a little, 
ince the axis of the k” rotation is near enough to said nadiral point 3). Then the whole 
eration is repeated from the beginning, until successive approximations have brought 
out the clearance of the y-parallaxes on the nadiral nuclear plane; normally this is 
ilteady achieved after the first readjustment of b," and k". 
HO 
1 
1 
Dr. Gino Parenti, “Device for recording the nadir position directly on the photograph 
i the exposure”, 
) 
i 
) Dr. Gino Parenti, “Experiences with recording the nadiral point by the Nistri method”. 
) See Note on next page. 
  
RERO REA ES SEA ES 
  
  
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