> 
45 
A model of superwide angle photographs was tested after analytical resititution. In this case known 
regular errors were corrected for as indicated above. The results are shown in table 4.4:3. 
Table 4.4:3. Super-Aviogon, c=88 mm. The Öland test area. Flying altitude 2600 m. Five control points in the model. 
Camera 
S ol5 
«m 
s m 
«m 
Rms-values of discrepancies 
check points 
mm in the terrain 
Corresponding theoretical values according to 
s ol5 an 4 conf. limits, 
mm in the terrain 
X 
y 
z 
X 
y 
z 
Super- 
Aviogon 56 
6.7 
7.9 
• 144 
226 
145 
140< 200< 360 
146< 209< 376 
127< 181< 326 
For the superwide angle photographs there is good agreement between the theoretical and practical 
accuracy. However only one model was tested. 
4.5 The Theoretical Accuracy of Photogrammetric Strip Triangulation 
In previous investigations (see reference 4.5:1) the laws of error propagation have been applied to 
various methods of photogrammetric triangulation, and formula systems have been derived expressing 
the accuracy of the triangulation procedures to be expected for specific conditions and approximations. 
The accuracy is expressed in terms of standard errors based on the standard errors of unit weight of the 
fundamental operations. The regular (systematic) errors of the operations mentioned are consequently 
assumed as known and corrected to the level of the irregular errors as expressed by the standard error. 
In this research program new values have been determined of these basic data of fundamental operations 
and, therefore, the corresponding accuracy to be expected from various triangulation procedures will be 
summarized, particularly with analytical procedures. Distinction will be made between cantilever 
extension and bridging between two control point groups. Wide angles cameras, vertical photography 
and normal conditions are assumed. 
4.51 Analytical Stereo-Radial Triangulation 
Cantilever extension 
The formulas for the standard error to be expected can be expressed as follows: 
h I n 
S-x 
I/ j (14/i 2 + 21 n + 25) 
Sy — So 
(10n 2 + 15/1 + 107) 
s 0 is the standard error of unit weight of the image coordinates, 
h is the flying altitude, c is the camera constant and n is the number of models to be triangulated. 
The standard error of unit weight, however, has been found to vary considerably over the image and 
therefore it is desirable to derive formulas in which this variation is taken into account. Such formulas 
become complicated in derivation and therefore it seems reasonable to use a mean value of the standard 
error of unit weight in the formulas shown above. According to the results of practical tests in section 
1.62 the mean value of s Q can be chosen as 0.01 mm. The distribution of the standard errors is shown in 
fig. 4.5:1 in the Appendix.