' 
meas 
Otherwise the procedure is idential. Due to complete correlation of dO 
or constant z one 
may conveniently omit all terms containing parameters ai. 
In view of the approximate relations (1) one may even omit all terms containing ai, bir ei and 
x' equations and 81, €i and f: in the Y' equations to avoid large a priori correlations. 
represented by equations (12c!) to(12h) is identical, € i ew of 
and d, may be omitted in the x' equations and a, Ys ; , in the 
is i i 
ance equations). The differential coefficients must however 
  
A purely stochastic approach for the modeling of time varying parameters is being suggested by Ebner 
at the 1976 ISP Congress (/28/): 
Instead of assigning quasi-observation equations for each orientation parameter at intervals x he 
uses than for every scan line j ; 
(12d) must then be replaced by: 
(1