contrast transfer and edge sharpness (acutance) on image measurement in various locations of the 
photographic format. Glass plate targets containing multiple contrast three bar patterns and a standard 
resolution target were photographed through a light source-collimator-camera system. A microanalyzer 
(microdensitometer combined with a precise comparator integrated with analog and digital recording 
capabilities) was used for the studies. Over two thousand edge measurements were made. The results indicate 
that, among other things, certain image quality parameters may be the controlling ones over image 
measurement capabilities in a given area of the photographic format. 
18. Hakkarainen, J. 
Finland 
THE RESOLVING POWER AND THE MODULATION TRANSFER FUNCTION 
OF TERRESTRIAL AND AERIAL CAMERAS IN WORKING CONDITIONS 
In 1971 two different test fields for the investigation of the RP and the MTF in working conditions were built 
in Finland, one for terrestrial cameras at the Helsinki University of Technology in Otaniemi, the other on the 
airfield of Malmi, near Helsinki. Both test fields consist of test patterns of the square-wave type suitable for 
microdensitometer measurements. 
According to the test photos the terrestrial cameras SMK 40, SMK 120 and TMK differ from each other 
considerably as regards the resolving power and the form of the RP curve. The test field of Malmi has been 
photographed with several different cameras under the same conditions. The RP and the MTF have been 
determined from the aerial photographs, the latter is calculated also with the Edge Gradient Analysis. The 
differences between the RP's of the cameras in working conditions seem to be small. The effect of contrast is 
strong both when terrestrial and when aerial cameras are used. Also some settled areas have been 
photographed for the Edge Gradient Analysis. 
19. Hakkarainen, J. 
Finland 
CALIBRATION OF AERIAL CAMERAS 
WITH A HORIZONTAL GONIOMETER 
A goniometer for the determination of the distortion of aerial cameras and for the periodic control of cameras 
was constructed in 1969. Since the article published in “The Photogrammetric Journal of Finland *’, Vol. 3, No. 
2/1969, this goniometer has been much improved as regards the illumination and the installation and 
measurement of the camera. Also, it has got a new grid done on a planeparallel glass plate with the standard 
error of about +1 wm. The new plate improves considerably the accuracy in measuring on asymmetric 
distortion. The standard error of distortion measured with the equipment is about +2 wm. Several cameras 
have been measured with the goniometer; the results are reported in this article. Also problems regarding the 
construction of the goniometer and the laboratory measurements of distortion are discussed in general. 
20. Heimes, F.J. 
Netherlands 
IN-FLIGHT CALIBRATION OF A 
SURVEY AIRCRAFT SYSTEM 
The in-flight calibration of a survey aircraft system is described for 180 turns and straight East-West flight 
lines. The turn calibration is executed for indicated angles of bank between 15°and 30°. A desired flight line 
spacing can be obtained by applying a corrected pre-computed angle of bank. The turn calibration is also made 
for Doppler spacings. For the straight lines, systematic angular errors and scale factors are computed from the 
actual track known from aerial photographs and the Doppler track. For turns and straight lines it is shown how 
the performance can be increased by an in-flight calibration.