effect of a single error source, or of a group of a few 
error sources, particularly if every attempt is being made, 
e.g. by using a reseau for the determination of the image 
deformation, to eorrect as many dimensional changes as 
possible prior to a general adjustment of the available data. 
It is the opinion of this reporter that the effects of 
insufficient film flattening in aerial cameras are today more 
important than the effects of dimensional changes in the 
aerial film. It appears that every attempt should be made 
to improve the effectiveness of the film flattening procedure. 
Two other problems deserving more attention tnan at 
present are the turbulence of air and other disturbanees in 
the ambient conditions in and around the airplane, and the 
effects of image quality on image geometry. It appears that 
the accuracy threshold level today has come close to the 
resolution limit of the lens-film-eombinations presently 
available. 
It is also the opinion of this reporter that we should 
now recognize that a standard aerial mapping camera cannot 
any longer meet the requirements for all applications. A 
camera to be used for analytical aerial triangulation may 
have more lens distortion than a camera which should be used 
to obtain photography for plotting purposes and for the 
production of orthophotos, but it should have a higher 
resolution and a sufficient number of reference points in 
the image plane for the elimination of the image deformation.