* 
3 
n3 
Sear al 
  
   
  
   
  
   
  
  
  
  
  
  
  
   
  
   
  
   
  
   
   
   
  
   
   
   
    
     
PO 
  
  
  
method for the determination of the quality of the prints and diapositives must | | 
EI. tot t 
worked out. The customers see only the positive photograph and natun]y | 
judge the work of the producer mainly by the quality of the contact prints 
539 Continued investigations 
For aerial photography in 1956 variable-contrast test targets will be testi 
Figures with density values ranging from 0.5 to 1.1 have been made, since the 
remission of the object is as a rule between these limits. Furthermore, the main 
importance is attached to testing the low contrasts from 0.05 to 0.25. In addition 
FAI 
the accuracy of horizontal parallax measurement is tested for certain frequency | 
and low contrasts of annular targets as shown by fig. 18. For this purpose the | 
aerial photographs are orientated in a stereo-plotter, and the right-hand roy ij 
targets is covered in one photograph and the left-hand row in the other, giving 
a faulty but easily measurable height effect. For both kinds of test targets th 
density values in the photographs will also bee measured with the aid of a mie. 
densitometer. The values obtained are compared with the results of ocular inspec- 
tions of the quality of the photograph, taking into account also the different 
fields of application of the photographic material. 
When a new and better aerial camera is available the gain can be obtained eithe 
by an increased altitude or by quality improvement. At present, the tendeny 
seems to point towards greater altitudes also for civil photography. For thi 
reason the test targets now made should be so large that values from altitude 
test contrasts 0.05 Oso Os O20 025 
© © 0.25 
© Q 0: 
Flight direction — Q Q 
015 
OO 0.10 
Fig. 18. Dark annular stereo-testtarg! 
a for testing the relation between 
0.05 = resolving limit and accuracy of 
height measurement 
no 
e 
52 
  
around 5,00 
can be usec 
out, larger - 
The inves 
be publishe« 
Fagerholm 
Fotogrami 
mars 1950 
Howlett, L 
1946. 
Welander, 
Fotogrami 
holm. 
. Washer, F. 
Circular 5: 
Kardas, R 
nr 2 1954. 
Perrin, F. 
tiom, J. € 
Harvard | 
of Factors 
31, 1945. 
. Mount W 
(ameras ir 
Aaelson, E 
Bulletin fr 
13. Baker, J. | 
1951. 
. Mac Dona 
Photogram 
. Higgins, G 
Power in : 
16, Carman, I 
J. 0. S. À 
. Bückstróm, 
barr av ol 
1953: 1 St 
Ingelstam, 
Photo elect 
Standards 
Lindberg, 1 
tiom. Opti 
. Ingelstam, 
by Mean : 
VIII Inter 
Edition no 
v 
cx 
> 
— 
e SCE pi 
b  — 
— 0n 
x wu 
Ps 
= 
18. 
oc 
1 
Bo 
c SS