217 
Cette pratique simplifie considérablement le problème de la compensation 
tant du point de vue théorique, que dans l’exécution pratique. La compensation 
de la chaîne de points nadiraux d’une bande comprise entre deux couples con 
trôles devient similaire à la compensation d’un cheminement planimétrique à 
polygone rectiligne. 
De plus, les formules obtenues montrent que cette méthode permet de corriger 
simultanément les erreurs accidentelles et les erreurs systématiques constantes. 
Transfer of Absolute Orientation in Aerial Triangulation 
The absolute orientation of a stereomodel is defined by four parameters: scale, azimuth, 
longitudinal and lateral tilt. Along a triangulated strip these parameters are altered by each 
transfer from one model to the next one. The differential errors by which these parameters are 
disturbed in each transfer may be expressed easily as functions of the errors of the relative 
orientation elements of the new photopair (in the case bzi = bz% = 0), or of the orientation elements 
of the new air station (in the case of ordinary model connexion). 
If accidental errors only are considered, it is possible to express, starting from the adopted 
methods of relative orientation and scale transfer, the weight and correlation numbers of the 
setting elements of the photographs. By application of the law of propagation of errors and taking 
into account the previously established functions, the weight and correlation numbers of the para 
meters of absolute orientation can also be computed. 
For the practically adopted methods, it is found out that the parameters of the absolute orienta 
tion are uncorrelated and thus compose a combination of independant variables, which may be 
considered for computational purposes as a set of directly observed quantities. 
Application of this principle gives us a clearer understanding and a more elegant and easier 
procedure of aerial triangulation adjustment. 
Cette communication n’est suivie d’aucune discussion. 
La parole est ensuite donnée à M. A. Bjerhammar (Suède) qui présente: 
»Further Results with the Parallax Triangulation Method». Résumé: 
According to Bachmann the adjustment of an aerotriangulation is performed 
after a primary orientation procedure. In this method the orientation of the 
individual model is made by technical methods and finally an additional numeri 
cal adjustment follows for the closure conditions of the whole chain. (Bachmann: 
Théorie des erreurs et compensation des triangulations aériennes. Lausanne 
1946) — In a later paper the author has treated the adjustment of the aero 
triangulation according to a new technique. (Bjerhammar: Photogrammetria II 
1950—1951: 4). In this method all 'parallax conditions of the orientations as well 
as the closure conditions of the chain are included in a common adjustment. This 
means that the sum of the squares of the residual parallaxes will be equal to 
minimum. The method is here called parallax-triangulation. The theoretical 
difference between the two methods may be explained in the following way. 
Residual parallaxes 
V — Vi -j- v 2 
and thus 
2 VV rr 2 Vi y I -f- 2Ï V 2 Vo -f- 2 2vi v 2 
where 
v x r= residual parallax after the primary orientation 
v 2 — added parallax to compensate the conditions of closure 
v = total residual parallax after completed adjustment. 
According to the method of combined adjustment there are three groups of 
necessary conditions to be fullfilled in order to get a minimum of the whole. 
1 : o 2 Vi Vi = min 
2: o 2 v 2 v 2 = min 
3 : o 2 2 Vi v 2 = 0 
A. Bjerhammar: Further 
Results with the Parallax 
Triangulation Method. 
(Publ. Ill B 2)