sufficient to determine the characteristics of a wide-field photo- 
gramnetric lens. Results were agreeably comparable. (Details, 
not presently in comparable form will be presented at the Congress.) 
Gliatti then analyzed the aerial photography, supplied by 
Canada which was exposed in the same two cameras, using edge gradient 
techniques. Again edges were selected such that the field was 
covered using both radial, tangential, and composite of radial and 
tangential lines. With the MTF of the film divided out, the results 
compared favorably with Rosenbruch's lens test, showing good control 
and a high confidence in use of this technique for evaluating the 
quality and the control of airborne photographic systems. 
The above four papers will be published in Photogrammetria ( e 
in a late 1976 issue. : 
  
4.3 In addition to the above Norton has summarized various inter- 
national standards on Optical and Modulation Transfer Functions 
and extracted results from significant papers showing the present 
status of this discipline. These are later paragraphs. (The papers 
on this image evaluation method would assemble into many large 
volumes so that it is impossible to either select or report on 
the most significant. We apologize for any seeming neglect.) 
4.4 Photogrammetric Applications of MTF's (Summarized by Welch) 
(References: 6 to 22) 
Modulation transfer function analysis techniques are now being 
used to both predict and analyze the performance of imaging systems. 
Prediction is normally accomplished by cascading the MTF's of 
individual system components such as the lens, film, image motion, 
and duplicating film to produce a total system MIF. Despite the 4 9 
apparent weaknesses of relying on manufacturers' data for lenses, 8 
films, and other system components, this method has been demonstrated 
to provide predicted MTF's which correspond to within 10 to 20 
percent of measured MIF's, Applications involving aerial photographic 
and satellite imaging systems are discussed by Welch and Halliday 
(1973); and Welch (1974a,b). 
The evaluation of system performance by MTF techniques is 
now a recognized procedure and has proved significant for the analysis 
of both aerial photographs and small-scale satellite images on 
which conventional resolution targets do not appear. The basic 
approach to the determination of system MTF's from operational 
images involves the edge gradient analysis (EGA) technique in which 
microdensitometer traces are made of sharp, contrasting edges 
recorded in the image. Typical natural edge targets include airfield 
runway patterns, field boundaries, and uniform coastlines. These 
edge traces are then transformed into MTF's by graphical, mathematical, 
or combined graphical-mathematical procedures (Scott, Scott and 
Shack, 1963; Jones, 1967; and Welch, 1971). Applications of the ( GO 
EGA approach to aircraft and satellite imagery are discussed by 
   
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