COMMISSION I 
Photography and Navigation - Photographie et 
navigation - Photographie und Navigation 
President: Mr. M.B. Scher, USA; Secretary: Mrs. C.L. Norton, USA. 
Monday July 24 1972, 13:45 
The Commission President welcomed the delegates. He introduced the Commission Secretary, the U.S. 
correspondent, J.R. Quick, the Chairman of the Working Group on MTF, E. Welander, and the Chairman of 
the Working Group on Remote Sensing, P.M. Fagundes. 
A Resolutions Committee, consisting of J.R. Quick (Chairman), G.C. Brock, S.K. Ghosh and S.A. Hempenius, 
was appointed. Suggestions for Resolutions were requested. 
The Commission President outlined the content and purpose of the Commission I Report. He reviewed the 
Resolutions affecting Commission I from the XI Congress and the action which had been taken on them. He 
outlined, also, the Commission programme for the Congress. 
The meeting adjourned. 
Tuesday July 25 1972, 15:45 
The Commission President welcomed the delegates and introduced the Secretary, the invited speaker, E. 
Welander, and the panelists G.C. Brock, A. Sorem, R. Jones and R. Welch. He then called on E. Welander. 
After delivering his Working Group's Report, Photographic Modulation Transfer Functions”, E. Welander 
called on the panelists for comments. 
R. Welch reported that he had determined subjective measurability thresholds for square images of varying 
sizes. The results correlated with maximum single-bar response measurements. Sizes were for Plus X, 30 pm; 
for 3414, 20 pm; for false colour, 60 pm. 
A. Sorem reported that Eastman Kodak Company carries out routine MTF measurements with white light, or 
artificial daylight, as reported by Lamberts (1969). Variable area sinusoidal test objects are smeared on a 
cylindrical lens. The microdensitometer is equipped with a low-pass filter to minimize 60-cycle noise and 
granularity. 
Kodak has a characteristic vector computer programme to predict the MTF curve from measurements 
at 5 frequencies, but generally all 23 frequencies available are used. 
Another method reported by De Palma and Jespers applies a Monte Carlo technique requiring only a 
measurement of scattering and absorption. It agrees well with the older technique, and avoids difficulties from 
adjacency effects. 
R. Jones listed the following as some of the problems in using edges: slit alignment, coherence, grain limitations 
and edge effects. However, he noted that edge effects also occur in photographs of ordinary objects, and, hence, 
should not be discarded. 
G. Brock reviewed the causes of adjacency effects, and recommended the use of a strong restrained developer 
such as D 19, thorough agitation and full development. However, it is not possible to avoid adjacency effects 
entirely, and in practice the exaggeration resulting may be useful, since the purpose of taking photographs is 
to see the ground, not to measure MTF. 
R. Welch said that for high-altitude photography and medium-haze conditions, a background reflectivity of 
10%, and a target reflectivity of 30 to 40%, are most suitable. The minimum length of the edge in the image 
should be 250 pm. 
E. Welander noted that 7 is not considered in measuring the MTF of an aerial photograph. This is neglecting 
a real image quality factor. He asked G. Brock if it would be possible to use densities instead of effective 
exposures to obtain something close to MTF.