56 GEOMETRISCHE EIGENSCHAFTEN DES BILDES, DISCUSSION 
“In the actual case the filter evidently has 
ruined the interior orientation of the camera 
and has introduced the correlations as stated 
in the reservations.’ 
These conditions are abnormal. To that 
I will only answer that in my opinion the infra 
filter has not ruined the interior orientation of 
the camera at all and I cannot understand why 
any correlation has been instituted unless I have 
used .. . [inaudible] .. . and the tilting element 
q only. I cannot consider the conditions as ab- 
normal, I have tilted every lens along in the 
same manner and I have got analogous results 
but giving a much smaller ¢ correction. 
Thirdly, perhaps these results will contri- 
bute towards explaining the model deformation 
of the aerial triangulation, as every model will 
cause a systematic tilt ¢ for the aerial model of 
about one minute, as shown in my paper. These 
tilts, in addition, will result in a systematic dis- 
turbance of the triangulation strip. 
Mr P. D. CARMAN: At the 1952 Congress 
on Photogrammetry we adopted for trial and 
discussion a specification of methods of cali- 
brating photogrammetric cameras. Since then 
there have been a lot of developments in photo- 
grammetry and it has become desirable to bring 
that document up-to-date. In the past few 
months I have given the national reporters for 
Commission I a lot of work, they have been 
selecting and preparing comments on the me- 
thods of calibrating cameras and sending these 
comments to me as a basis for revising the spe- 
cifications. 
As a start on this operation Mr Cruset sent 
to me a number of comments he had already re- 
ceived, and from these a draft revision of the 
document was prepared and circulated to the 
reporters in March. 
It was sent to them in sufficient quantities for 
them to pass copies on to the most interested 
persons in their countries. By May I had re- 
ceived enough comments so that it was desirable 
to circulate a list of the proposed amendments, 
and in July, on 15th July, a full second draft 
was sent out to the reporters. I had hoped that 
by then I would have received most of the com- 
ments which were to be made at this time, and 
that the draft of 15th July would be very nearly 
a final one. I found, however, that very many 
comments were received after then, and some of 
these comments were very important ones 
which had to be included. This has led me to 
prepare a third draft provision of this docu- 
ment, and this draft, dated 26th August, left 
Canada ahead of me by air, but arrived here 
after me and got to this building on Tuesday. 
It has been distributed to the reporters by means 
of the pigeon-holes outside, and I hope they 
have received. Further copies are available 
from the distribution centre for technical docu- 
ments, and I hope that those of you who are 
interested in this subject will obtain these spe- 
cifications and look them over. 
All this work by the national reporters and 
by the specialists whom they consulted has 
made possible a large number of improvements 
in the document and I wish to thank these 
people very much for all their efforts. However, 
in spite of all that has been done by all these 
people, this draft provision is not perfect. I 
think it is important that we should realise and 
admit that this document never will be perfect, 
it necessarily contains compromises between 
different points of view, different photogram- 
metric requirements and different laboratory 
methods. Compromises of this sort are never 
entirely satisfactory and in addition photogram- 
metry is a developing science. Things keep 
changing, improvements are always coming 
along, and a standard can only follow these im- 
provements after it is established that they are, 
without a doubt, desirable. So our document 
will always be somewhat out-of-date. I believe 
that the present revision does the best that is 
possible under these circumstances. 
However, I want to suggest that the Commis- 
sion I should maintain a standing arrangement 
for collecting opinions on this standard and for 
making revisions in it when these become ne- 
cessary. I would ask that these arrangements 
should operate from a country other than Ca- 
nada, we have been associated very closely with 
this document, and 1 am afraid that although 
we have tried our best to be impartial we have 
undoubtedly introduced our points of view into 
it in places to an excessive extent. 
I cannot take the time here to discuss in de- 
tail the changes which have been made since 
the 1952 document. A great many of these 
changes are clarifications or alterations to bring 
it up-to-date, and I do not think these make 
major changes in the original intent of the docu- 
ment. There are a few major changes which I 
would like to mention briefly. The document has 
been named a recommendation rather than a 
specification, since the term specification im- 
plied a performance specification in some coun- 
tries. The term recommendation also has the 
advantage that it agrees with the terminology of 
the International Standards Organisation. 
In the preamble of the recommendation, it 
has been pointed out that the recommendation 
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