-23- 
In the case of aeroleveling, the error formulae are as follows : 
(18) 
Ar p =X[ < /x.) + X*- + Y(jS'-Ss] + y z 
(19) 
(20) 
2.3 Correlation Factors Between the Various Quasi-Observations of The 
Cross-Bases Method 
As mentioned before, the quasi-observations used in the Cross-Bases 
Method are: 
S; Scale of the stereopair (i, i+l), 
K; Azimuth of any given line in the stereopair (i, i+l), 
Lateral tilt of the stereopair (i, i+l). 
<J> Longitudinal tilt of the stereopair (i, i+l). 
The errors in the elements of relative orientation (Xa } ¿VI,fa 
bzj. ? byi ) of model i could be given as a function of the errors in 
the elements of relative orientation of the preceding model (i-l) and 
the differential errors in these elements, as follows: 
AX^ = AXx-| + J XjL 
A UJX - A ¿Vi-/ -b XuJa 
A - A + ‘¿4‘À 
(21) 
(22) 
(23) 
* Statoscope errors are not included, should be treated separately.