(D 
Li 
and point grouping strategy in use. Thus if the operator does not want to, 
he is very seldom forced to do manual point numbering. An automatic system 
of this kind is indeed practically free of gross errors which easily occur 
when typing point numbers in. 
L.L UPDATING OF PARAMETERS 
As mentioned above, all necessary unknown parameters are updated in real-time. 
The transformations updated are relative orientation based on the coplanarity 
condition or triplet formation based on the six-parameter solution (Kratky 
/ 5 /), and in addition the seven-parameter similarity transformation based 
on the simultaneous solution. The updating is normally after the sixth ob- 
servation on the model based on the direct editing of the Cholesky factor 
(Inkilià / 4 /). If any malfunction of the updating due to the non-linearity 
is suspected the operator can press the menu key "update'' (Fig. 2).Then the par- 
ameters are updated by forming the normal equations and thus performing full 
computation of each transformation. The computation of all parameters by 
updating directly the Cholesky factor takes only a fraction of a second. 
4.5 QUALITY CONTROL 
One important goal for a measuring system is to enable the control of the 
observations quality to be carried out as early as possible and also to 
direct the operator to improve the geometric quality of his work. In the 
system in question the quality of the model is checked by computing the 
reliability numbers of Baarda's theory. This system is of course limited 
when speaking of improving the quality of the total block, because the 
operator is always working only on a very small subarea of it. The gross 
errors are always detected by computing the standard errors of the residuals 
and by using the t-test, if 89 of the adjustment does not deviate from the 
previously computed ones significantly. If it deviates, the normal distri- 
bution and the "true So are used.(CF. Baarda /1/, /2/.) 
The menu shown in Fig. 3 is displayed on the operator's panel when a gross 
error is detected. 
Fig. 3. The menu displayed on 
the operator's control panel 
when a gross error is detected. 
  
4.6. SOME ASPECTS OF IMPROVING THE OPERATIONAL ITY 
The system uses a lot of menus when communicating with the user. These are 
displayed on either the operator's panel of the DSR 1 or the screen of the 
terminal. Also a strategy for giving advice to the user is always heavily 
incorporated.