(215) 
errors, but I must, in justice to the Secretary and myself, make it quite clear 
that if anyone in any country was not consulted on the preparation of the 
draft specification in the period January 1952 to the date of the Congress, he 
must place the blame upon his national reporter and not upon the Chairman 
and Secretary of the Commission. In this connection I must express very deep 
gratitude to those who, during the last week or ten days, gave so freely of their 
time and effort to help us introduce certain revisions that we think should 
make the specification acceptable to all countries. Without their help the work 
of the last eight months would probably have been lost, and we would not 
have been able to present the following resolution to this meeting. 
Resolution. 
Be it resolved that the Specification of Methods of Calibrating Photo- 
grammetric Cameras and Measuring their Resolution, Image Illumination, and 
Veiling Glare with the modification agreed to by the National Reporters be 
adopted for trial and discussion, and that it be subject to continual review by 
Commission I. 
Is there any discussion on this resolution? 
Dr. Tham: This test specification in the section on calibration requires 
that the lens distortion curve or equivalent data be presented. The lens distor 
tion curve tells only the quality of the objective but gives no direct information 
about the influence of the distortion on stereo measurement. For example, the 
distortion curves of the Aviotar and Aviogon objectives have approximately 
the same amplitude, about ± 8 to 9 microns. Computing the influence on a 
stereo measurement, however, will show that the effect on height for the 
Aviotar will be about four times that of the Aviogon. Vertical parallaxes are 
much more favourable for the Aviogon than for the Aviotar. I have written an 
article on the presentation of distortion effects which will be published in the 
next issue of Photogrammetric Engineering. My proposal is that instead of the 
lens distortion curve, there be given nomograms showing the height correction 
and the residual vertical parallaxes for a certain selected camera constant and 
altitude. I hope that this important question will be discussed more to give us, 
and to give the user, a possibility of defining the qualities of photogrammetric 
objectives. Thank you. 
Dr. Howlett: Thank you very much, Dr. Tham. I think that Dr. Tham’s 
suggestion is a very interesting one, and I think it is rather happy that it arises 
at the present time because it is an example of quite a number of other com 
ments which might be made in that there is nothing in the specification that 
precludes the thoughts which Dr. Tham has expressed. We have striven all 
through the preparation of this specification to include nothing that would 
place any restriction on the way in which the results were presented. The dis 
tortion curves are required by the specification, but anyone can convert those 
into any other arrangement which he sees fit. 
Mr. Pryor: U.S.A., Although Pm not the reporter for the United States, 
I’ve been working rather closely with him and I would like to take this opport 
unity to speak for the American group and apologize for our slowness in react