PHOTOGRAMMETRY TAKES THE POSITION
OF THE THIRD MAN
Gomer T. McNeil
PHOTOGRAMMETRY, INC.
Silver Spring, Maryland
Subsequent to World War II, a small group of civilian photogrammetrists employed by
the U. S. Naval Photographic Interpretation Center, were presented numerous photogram-
metric problems of a non-topographic nature. Unfortunately, security restrictions pre-
clude the revelation of these projects at this time. It is necessary, therefore, to con-
fine this paper to experiences and opinions detached from the military. This approach
severely limits the scope of interesting projects to relate, since the previously referred
to group of photogrammetrists have been in the commercial business of non-topo-photo-
grammetry for only the past nine months.
From the early conception of this new venture, it has been an established policy to
pursue the field of non-topo-photogrammetry from the position of the third man. An excel-
lent example of the position of the third man is the Certified Public Accountant. The
accounting records of business firms are audited and certified by the CPA. The financial
statements are then made available to the company’s stockholders and to the Department
of Internal Revenue for income tax purposes. The CPA, in effect, is working independ-
ently in fact and theory for the company and government. The photogrammetrist would
be placed in a similar position of integrity and trust as the CPA. Probably the laws of
the state would require the photogrammetrist to be registered as a professional engineer.
Assume that the XYZ Company is under contract to the government for the production
of a gyro-stabilized camera mount whose vertical axis is not to deviate more than 5 min-
utes of arc from the plumb. Obviously the XYZ Company would evaluate the performance
of the gyro mount before delivery to the government and quite Possibly under the surveil-
lance of a government inspector. The production run, or representative sample lots of the
production run, would be forwarded to an independent photogrammetric organization for
evaluation and reporting of factual data on the performance of the equipment. ]t appears
that this procedure would function to the mutual advantage of the contractor and govern-
ment, inasmuch as the third man has no established obligation to the contractor or govern-
ment. Other items to be evaluated may consist of lens and camera calibration, weapons,
and airborne equipment. A very limited investigation as to the feasibility of this proposal
has already resulted in favorable reactions.
It has been our experience that when a photogrammetric evaluation was presented,
there arose a compromise in the allocation of personnel and equipment between the
special problem and the normal routine. Weeks or months were expended in procuring
and modifying reconnaissance equipment, and in many cases, only to have it disbanded
subsequent to the test. It is obviously more efficient to obtain the most precise photo-
grammetric equipment available and thoroughly calibrate it. The equipment should be
reserved for subsequent tests, and the accumulation of data from each test would enhance
the precision of the equipment.
Photogrammetry is an excellent means to reference an object in motion at a given
instant of time. The object may be an aircraft, missile, cloud, wave, landing craft, or
the like. It is believed that photogrammetry has not been fully exploited in this regard.
The greatest application of photogrammetry has been in the field of map making. Inas-
much as large areas had to be mapped in a productive manner, photogrammetry became
highly instrumentized. Instrumentation removed a greater portion of the mathematics of
photogrammetry, and the latter, figuratively speaking, has become somewhat of a lost art
to many competent instrumental photogrammetrists. It is for this reason that some facil-
ities are not capable of conducting comprehensive non-topographic evaluations of which
the basis is mathematics. This condition is perfectly excusable when it is realized that
the fundamental purpose of the majority of photogrammetric organizations is to compile
maps. The mathematical or analytical approach is justified, at times, inasmuch as the
metrical analysis of a few points or lines do not warrant the time or finances to capitalize
data reduction instrumentation for short-term projects. When the project is of a long-term
or productive nature, the mathematical approach is still a prerequisite to establish the
parameters, design, and performance of the data reduction equipment.
The greatest problem confronting the photogrammetrist in conducting non-topo-evalua-
tions is the lack of a photographic system designed for a specific purpose. This is es-
pecially true when requirements dictate wide-angle coverage at a recycling time less than
that normally encountered in aerial mapping cameras. The problem of recycling immedi-
ately introduces us to the related field of motion picture and high-speed photography
which has shown great progress and accomplishment. It is apparent that much can be
gained from the mutual consideration of non-topo-evaluations by the combined efforts
of the motion picture engineer and the photogrammetrist; particularly on projects involv-
ing the metrical analysis of phenomena in motion.
Mr. Kenneth Shaftan, Society of Motion Picture and Television Engineers, has pre-
sented the following definition: ''To aid in codification and unification of the field en-
compassing the scientific uses of photography, we need a term to describe it adequately.
The-term, photographic instrumentation, is proposed and defined as: “The use of the
photosensitive medium for the detection, recording and/or measurement of scientific and
