1easure- 
e image 
ulations 
n of the 
distance 
3. Since 
of the 
:d in the 
ed from 
ge coor- 
ot mag- 
cameras 
ms were 
e of the 
nents in 
se Table 
ge coor- 
e 150 
rding to 
e film 1s 
used. A 
r of the 
espectiv- 
sponding 
ind to be 
additio- 
1 photo- 
eometric 
with the 
tographs 
ipon the 
perature 
tographs 
)hs taken 
method. 
ilter was 
nnection 
cameras 
ig power 
6.7 For tests of the geometry of oblique photographs a perspective 
grid was constructed and the corresponding equation solutions were 
performed. The practical tests were satisfactory. 
6.8 The results of the tests of photographs from aerial cameras in 
a high tower and from the air have clearly indicated that many basic 
geometric problems of the fundamental operation number one of aerial 
photogrammetry, the photographic procedure, can be successfully treat- 
ed in this way, in some cases only in this way. It 1s desirable to continue 
the investigations. 
6.9 The reliability of the estimation of accuracy can be found from 
confidence intervals according to well known statistical methods. If the 
adjustment is performed in 5 points the number of redundant measure- 
ments 1s 4. For a confidence level of 5 per cent the confidence limits 
are found to be 0.60 s, and 2.90 s, respectively. For 2 per cent confid- 
ence level the corresponding limits are 0.55 s, and 3.65 s . After ad- 
justment in 9 points the number of redundant measurements is 12. For 
the confidence level 5 per cent the corresponding confidence limits are 
0.71 s, and 1.66 s . For the confidence level 2 per cent the correspond- 
ing confidence limits are 0.67 s, and 184 s. 
Acknowledgements 
[In the experiments the following persons have taken part: From The 
Geographical Survey Office: M. Forsell, T. v. Wachenfeldt, K. B. 
Segemark, K. Thulin, H. Krosse. From The Board of Land Survey: 
C. O. Ternryd, L. Ljunggren. From The Division of Photogrammetry 
at the R. Institute of Technology: B. Hallert, L, Ottoson, E. Sigmark, 
5. 5j00, B. Shmutter. 
The measurements in the photographs and the computations have 
been performed at the Division of Photogrammetry. 
Financial Support has been given by The Swedish Technical Rese- 
arch Council. 
7. Application of the grid method for investigations of terrestrial 
photographs of various kinds 
The grid method has successfully been applied to investigations of 
photographs from a great number of terrestrial cameras, microscopes, 
and X-ray instruments. 
A. few examples of the results of the test of microscopes will here be 
demonstrated. 
The tests have been performed with the aid of small grids which were 
photographed through the microscope in the usual way and also with 
grids which were located in the camera and projected backwards 
through the microscope. In the latter case the image was photographed 
57