(387) 
C 
  
  
8 values of bDZ which are plotted as ordinates on graph paper at an enlarged 
t scale. 
If the photographs are correct the by and bz coordinates locate points on 
the same straight line. 
An abnormal y-parallax in one of the points A or A’ is indicated by a 
failure of alignment of the corresponding bz, the by having been aligned. 
An anomalie in one of the N points is indicated by an opposite error of 
alignment of the two points at À and A". By introducing by in the system as 
shown by the lack of alignment on the graph, and removing the parallaxes in 
7 these points by bz, one can prove that the same value of by will help both 
points, if the light rays of these points are not themselves affected by the 
deviation. 
The y-deviation of one or several perspective rays of points of orientation 
causes a failure in the alignment of the by and bz coordinates of the graph and 
B-error will remain. This error introduced in the by of other planes a failure of 
alignment function at different distances zo from the points N, and in the bz a 
failure of alignment function in distances z and y; they make impossible the 
total removal of parallax from all the points of a plane with only the bz motion. 
The plane of orientation should be abandoned and another one used. 
In resumé, it is possible, by the preceding simple and rapid method to 
diagnose the transverse deviations of perspective rays detrimental to relative 
crientation. The points affected by these deviations must not be used in the 
) relative orientation. The parallaxes that remain in the zones of deviation must 
be removed locally by by when one wants to see the image of these zones 
stereoscopically. 
The corrections of parallax by by and bz must be repeated several times 
to reduce the accidental errors; the values used are the average of the results 
obtained at each point. 
  
—— "(D CD 
gn 
  
  
  
IDENTIFICATION AND CORRECTION OF THE EFFECTS OF 
LATERAL LOCAL DISTORTIONS IN THE PERSPECTIVE 
BUNDLES IN STEREO TRIANGULATION 
> by 
George Poivilliers. 
  
  
  
Abstract. The lateral local distortions of the perspective bundles cause linear 
errors of points in pairs of photographs in stereo triangulation. These distortions 
can be analyzed and their effect can be eliminated. 
In a recent article I indicated the existance of abnormal local distortions 
of perspective rays due particularly to asmospheric refraction. I showed that 
the effects of the y-parallax of these deviations were related to the relative 
orientation of the stereoscopic model and how, by an appropriate method, it 
was possible to diagnose these transverse deformations and to eliminate their 
effect. 
The y-component changes the stereoscopic parallax and also the heights z 
of the terrain mapped. In an isolated pair, the error dz which results can be