SOME EXPERIMENTS OF SEMI ANALYTICAL TRIANGULATION 
17 
adjustment. To give an example, we can say that an error of 1 mm in the coordinate 
As causes an altimétrie curvature of the strip that, after the linear transformation, 
leaves in the middle an altimétrie error of 15 m. 
The residual errors after linear adjustment do not depend, therefore, on the 
errors on the instrumental coordinates of the taking points, since the size of these 
errors should be of 0,1 ~ 0,2 mm, that is in contradiction with the obtained precision. 
This question may also be investigated in the comparison between the results 
of the linear adjustment of the 2.6.1, I measure and of the 2.6.1, II and III me 
asures. 
We can see that the errors in Z have different signs. Then it is possible to remark 
from the results of the parabolic adjustments, that these errors have been practi 
cally eliminated both in the first case and in the other two. Since we cannot think 
that these differences depend on errors on the taking points, it is impossible to 
establish, in the present situation, the reason of the two different behaviours. 
To allow numerical comparisons with the results we obtained in our Institute 
for strips 2.6.1 and 2.6.4 executed in analytical or analogical way, we drew up the 
following table showing the mean values M and the standard deviations of the 
errors computed both with the residuals of the linear transformation and with 
those of the parabolic transformation. 
Measure 
Errors after linear transformation 
(meters at ground scale) 
Errors after parabolic transformation 
(meters at ground scale) 
2.6.1 
2.6.4 
2.6.1 
2.6.4 
Mean 
value 
Standard 
deviation 
Mean 
value 
Standard 
deviation 
Mean 
value 
Standard 
deviation 
Mean 
value 
Standard 
deviation 
X 
COORDINATES 
I 
— 0,21 
± 0.36 
+ 0,54 
dz 0,66 
+ 0,05 
± 0,22 
— 0,03 
± 0,27 
II 
— 0,42 
± 0.57 
— 0,09 
± o, 2 7 
+ 0,15 
± 0,25 
0 
± 0,22 
III 
+ 0,33 
± °>4 6 
0 
+ 0,28 
- 
Y COORDINATES 
I 
+ 0,02 
± °> 1 7 
+ 0.18 
± 0,31 
-— 0,01 
± 0,15 
0 
± 0,26 
II 
-0.34 
± 0.45 
+ 0,20 
± 0,34 
+ 0,02 
± 0,15 
+ 0,3 
± 0,19 
Ill 
— 0,49 
± 0,62 
— 0,05 
± 0,24 
z 
COORDINATES 
l 
— 0,71 
± 0,91 
— 2,42 
± 2,76 
+ 0,24 
± 0,38 
— 0,01 
± o,33 
II 
+ 0,76 
± 0,98 
—1,83 
_j_ 2,12 
+ 0,25 
± o,37 
— 0,03 
± 0,31 
III 
+ 1,12 
± 1.35 
+ 0,12 
± 0,29