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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