Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 197
SESSION V: DISCUSSION
CHAIRMAN- Brig. Gen. Victor A. Byrnes, USAF (MC)
PANEL DISCUSSION
C. L. Crouch, Illuminating Engineering Society and Illuminating
Engineering Research Institute
Jack W. Gethard, Applied Physics Laboratory, The John Hopkins University
Robert H. Brown, U. S. Naval Research Laboratory
GENERAL DISCUSSION
Speakers as noted
197
OCR for page 198
SESSION V: DISCUSSION
Panel Discussion
C. L. Crouch: The organizers of this program are to be congratulated upon
fulfilling one of the important functions of the Vision Committee, that is bring-
ing representatives of many disciplines together for discussions of common
problems. Each specialist in his own field goes home with concepts from others,
and we derive something uniquely better from the cross-~ertilization of dis-
ciplines. We better appreciate, now, some of the problems of the illumination
of radar and sonar displays.
In much simpler form, we have these problems in our ordinary practice
of illumination when we must see things involving areas of high brightness
and low brightness. We constantly have a change of adaptation and, perhaps,
overstimulation in the form of glare, so that when we try to see things, we can
~ Or Fir ~ r ~ ~ 1 ~ ~
not. vve nave formulated these pro olems as being very definitely concerned
with transitional adaptation.
In the Illuminating Engineering Research Institute, we are proposing to
study this phase intensively in the near future to find out what goes on as we
look here and there, and how effectively we do see a normal interior. What is
the sequence of eye positions in looking about from place to place as we carry
on our activity? If we know the sequence, and if we know the limitations of
seeing in each particular position, then we can really begin to design in terms
of all the factors involved. This was brought out very well in the discussion of
formulating in terms of total design' of all factors involved, and then intelligent-
ly proceeding to develop answers to the problem, perhaps through actual model
study. I especially appreciated this viewpoint of considering the difficulties of
looking from a high-brightness to a low-brightness area.
J. W. Gethard: I have no idea how ill Paul Fitts is (Ed: Dr. Fitts was
scheduled to be on the Panel, but was taken ill and could not attend the sym-
posium), but in many respects he may be the lucky one, since he doesn't have
the problem of trying to draw together such a diverse program as this. The
20-odd papers pose a staggering problem of integration. The Vision Committee
has certainly been given a new look in many respects. Whether this new look
will be pleasing to all is a matter which those who have attended the sessions
and managed to sit through all of them will have to decide for themselves.
There has been something for everyone, including, perhaps, a certain amount
of disappointment for a few. I say this despite my appreciation of the difficulty
of putting together a talk with slides and getting up before a group of people
to present it.
I think that yesterday's program (Ed: Sessions I and II) was rather dis-
appointing except for some of the scientfic papers. I believe that the absence of
more salt and pepper in the form of scientific papers has been felt as a loss
by a number of the attendees. In my opinion, no new material was presented
yesterday that was very exciting, and certainly there was nothing presented
in a form that the Vision Committee could get its teeth into. In the past' it
-198-
OCR for page 199
has been the policy of various groups' chiefly the military, to bring before the
Vision Committee certain problems that it would like to see studied by the
Committee. These were usually problems with challenging visual require-
ments. Yesterday' however, I heard no such problems presented. Instead a
group of operational requirements were paraded before us that looked to me at
least 15 years old. The only new operational requirement that I remember, and
I may remember this for some time, is the requirement for "anchoring per-
sonnel in the environment." I don't know quite what the Vision Committee
could do about a problem of this kind. It has been pleasing to learn of the suc-
cess of the blue-lighting venture of some years back, and it also has been most
interesting to hear a review of the possibilities of spot lighting for working en-
vironment. Nevertheless, I recall no new general methods or even specific
methods that were presented.
Today's session picked up considerably and the papers were better. While
there were a few disappointing features, there was a great deal of improvement
in today's program (Ed: Sessions III and IV). I had hoped to hear during the
Symposium something about noise and visibility, especially with regard to
serious electronic countermeasure problems that the military are facing; some-
thing about new display techniques; something about the possibility of compar-
ing the visibility function on cathode-ray tubes when the eyes are pitted against
automatic detecting devices; and something about the problem of comparing
visibility with detectability two quite different things, I think. In general we
have heard something about each one of these. The only one that was not
mentioned at all was the problem of comparing the eye with automatic de-
tectors. Automatic detecting systems certainly are coming along; unless the eye
is to be put out of business7 someone will need to make a careful evaluation of
the eye as a detector, as compared with the machine. This may fall in the
classified area, however, and I rather suspect it does.
I think perhaps the Vision Committee needs a new working group on visual
displays. It had one once, around 1948-1949, I think. It was dissolved, primarily
because it didn't do very much work. Perhaps the reason why it didn't is still
to be seen, in part' even in today's proceedings; that is, we do not yet have a
fundamental statement of what the visual display problems really are. Until
a thorough-going analysis of the display problem is made, it is rather difficult
to see precisely what such a working group of the Committee would do. I think
the first thing that should be done is this: we should have a group evaluate
the classified material in much the same way as the Committee as a whole
was able to evaluate the unclassified material during the last two days. I think,
however, it would be a mistake to bring together the entire body of the Vision
Committee to make this evaluation, as was done here. :!Rather7 I believe that a
small working group should gather together the material, filter it, evaluate it,
and present it to the Committee in a discussion of perhaps not more than an
hour's length. From the Committee's standpoint of getting at the basic problems,
I think the meat of yesterday afternoon's program could have been presented
in an hour's discussion and perhaps, in some respects, would have been pre-
sented better than it was by the individual discussants. Essentially, what the
- 199
OCR for page 200
Vision Committee needs to know, I think, and what at least I was unable to find
out after two days, is precisely how the Committee can assist the military in the
visual displays area. Perhaps Dr. Brown has some ideas how this can be done.
Finally, I would like to put in a good word for the speakers who described
some of the new developments in the display field. These new techniques and
the results that are anticipated will add greatly to the uses of visual displays
employing cathode-ray tubes.
R. H. Brown: Mr. Crouch and Dr. GeLhard have stated, very clearly,
their summaries of the symposium, and they have covered the ground quite
well. I would like to touch on a few points. May I thank the committee which
organized the program for the symposium. I would also like to thank the speak-
ers who, on relatively short notice, prepared their talks, submitted abstracts,
and in many cases had manuscripts ready.
Let me touch briefly on the sessions of yesterday, which seemed to me
to be confronted with some critical problems in the general area of visual dis-
plays. Since World War II, a major development in the use of radar and sonar
displays has been low-level lighting, which allows men to do other things than
look at radar scopes. At the same time, the introduction of low-level lighting,
whether broad-band-blue or localized lighting with extensive use of sheet polar-
izers and spotlighting, does introduce new problems. If one looks at some of the
new-classical literature, say Human Factors in Undersea Warfare or other sys-
tematic summaries, one finds most of the discussion directed toward relatively
high light levels. And it seems to me that data are needed for some of the lighting
problems which were taken up yesterday.
There was a difficulty in terminology, both yesterday and today. I was
confused, for instance, by the use of "blue-foot-lamberts." I was also confused
by the use of the term "signal-to-noise ratio." In one case, it was used in refer-
ence to luminance; in another case, it was used in reference to the inputs for
a radar indicator or system. This question may be related to the adequacy of
a lighting system. One may evaluate it in terms of the luminance on the cathode-
day tube, or one may evaluate it in terms of signals to the indicator or system.
Surely there seems to be a need for a working group on visual displays which
could report annually to the Committee on Vision.
General Discussion
Knoll: This morning I made the suggestion that perhaps there was an area
here where some of the contrast data could be applied. Since then several people
have pointed out to me some of the difficulties which at the time I didn't appre-
ciate. Difficulties, for example, such as the fact that on a radar display the
background luminance is not uniform. A second objection to trying to apply
these data is that, particularly in the PPI presentation, luminance varies con-
tinually for a given point on the scope presentation. Certainly these are diffi-
culties which are not insurmountable. A serious attempt should be made, per-
haps beginning with a static presentation of some sort, to see if the data can be
applied, and can be applied with some degree of accuracy. Then perhaps it
200
OCR for page 201
would be another step to go on to non-uniform backgrounds which vary not
only in a spatial sense' but also in a temporal sense. It seems to me incredible
that one will have to go through each of these different types of CRT presenta-
tions, systematically running a number of subjects through to attempt to get
some data in this way. If the luminance characteristics of cathode-ray tubes
could be made available, perhaps the Committee on Vision could translate these
into visibility data.
Gebhard: With respect to what Dr. Knoll said, I think it's quite true that
a great deal can be done along the lines of making the calculations he has in-
dicated; and as a matter of fact, I think C. T. Morgan said as much in a pub-
lication in which he attemped to summarize the work that had been done by
Hopkins on radar displays some years back. There has arisen in recent years,
however, much concern about what happens when the display contains noise,
especially noise of differing characteristics. Such noise, I think, tends to make
difficult the kinds of calculations that could be made quite easily on relatively
noise-free scopes, although there may be ways of getting around this analytical-
ly. This is a good example of the sort of thing that could profitably be taken
up in a working group on displays.
Ballard: I would like to ask our stormy petrel panel member a question.
He remarked that some of the things we heard yesterday were old, and in-
deed I remember hearing about the broad-band-blue system for quite a few
years. Of course it was highly classified back in the early days; as a matter
of fact, the color blue just missed being made secret at Wright Field at one
time, as I recall! But seriously, even though some of these things have been
known for some time, I'd like to ask Dr. GeLhard whether he thinks it is still
worth while pulling them together in one place, as has been done at this sym-
posium, and more particularly, whether it is worth publishing the proceedings
including all of these papers, so that in one book, which you can hold in your
hand, you can see the broad picture of the radar display problem, including both
the old and the new, as we have seen it these past two days.
Gebhard: Emphatically yes, in answer to Dr. Ballard's question. I per-
sonally would prefer to hold a book in my hand and sit in a comfortable chair
picking out those portions I wanted to read than sit on these hard seats for two
days to accomplish the same results. I can only repeat that some of the ma-
terial doubtless could have been boiled down some of it probably would be
thrown out, I think, by an editor. Perhaps this should have been the way to
handle the Symposium I don't know. Talk after the fact, of course, is very
easy. It's much more fun being a stormy petrel than being a program chair-
man, and much easier.
Miles: It has been a special pleasure to attend this symposium of the
Vision Committee after having been absent from the United States for three
years. There are one or two points I would like to call attention to. I think it
Arise to begin studying acuity and such problems in association with the move-
ments of the eyes. Pursuit movements' saccadic, and compensatory eye move
201
OCR for page 202
meets constitute factors that are implicated in visual performance. We have
long neglected adequate study of them. New insights in this area may prove
useful.
I have a problem in my mind, suggested by our program, though perhaps
this isn't a good time to take it up for full discussion. We are presenting patterns
and constellations of colors and lines on these scopes for the purpose of giving
men information for use in operating the machines. We expect them to read the
information symbolized on the scope. I remember that in studies of the process
of reading by photographic recording of eye fixations and saccadic movements,
it is very easy to distinguish a reading record of a man who knows mathematics
when he is reading material that includes mathematical formulas from a record
made by a non-mathematical reader. It is the same way for a man who knows
chemistry and is reading an article that includes chemical formulas. The men
who know these technical subjects spend about five times as long on such
formulas as do the men who don't really understand them. It is the general
rule that for every item in the formula one fixation is required, or at least
used. A formula that contains half a dozen items usually gives a record show-
ing the eye fixating back and forth, not always progressing left to right, and
continuing this attentive behaviour for one or more seconds. One or two five-
letter words in context usually requires less than the perceptual span of a
. . ^. .
simple fixation.
When we are presenting live material on the scopes for resolution and
information of operators we may underestimate the time that they are going
to require in visual fixations to get the information. If it is regular information,
symbolized by a square as different from a circle, it may perhaps be read very
fast. But if it's new information I would predict that if our eyes continue to
work as they do in the process of reading technical printed matter: the man
who really wants the information even though he's able to interpret it quite
quickly and know its meaning, will tend to make successive fixations on various
bits of that information.
Brynes: Thank you7 Dr. Miles, I can't refrain from remarking at this point
what a pleasure it is to have Dr. Miles back with us. He is one of the deans of
the Vision Committee. When I first came with this Committee many years ago
he was a member of the Committee and one large part of its backbone; he's
recently spent three years in Turkey; he's now back in this country, up at the
U. S. Naval Medical Research Laboratory in New London; and we're certainly
delighted to have him here at this meeting.
Crouch: In reference to Dr. Knoll's comments I am wondering if some of
the instrumentation which we are developing at I.E.R.I. might not be helpful.
We find that you cannot apply, in the ordinary work tasks, the theoretical con-
trast data because of the variations which occur in the background and in the
configuration of the detail. For instance, pencil writing is non-uniform and
varies from point to point. We have developed a contrast threshold meter which
"floods" the task or the detail with an increasing overlaying brightness to thres-
hold, inserting at the same time an absorption in proportion to the flooding
-202
OCR for page 203
action which keeps the adaptation level constant at all times. Then we come to
threshold by decreasing the contrast to threshold. With this instrument we are
able to evaluate much more precisely than by estimating from taking various
minute measurements of the detail and its background and trying to determine
variations of contrast. We can get threshold very quickly. The visual task
evaluator, which you heard Dr. H. R. Blackwell mention yesterday morning'
is now in rather large sizes but will be miniaturized for use in the field in
portable size. Using this visual task evaluator' any complex configuration can
~· ~ · ~
1 ~
be rectucect to its thresho~ct. one ot the earliest forms of this was used by Dr. L.
A. Jones of the Eastman Kodak Company in the first World W ar' In the
measurement of the effectiveness of camouflage.
Illuminating Engineering Institute research is producing several other in-
struments. For the problems of various brightnesses in the field of view. Dr.
Glenn Fry is developing for interior lighting engineers a portable disability
glare meter which can be set on a tripod for measuring in any position the dis-
ability glare present. Dr. S. K. Guth has already developed a meter which
measures discomfort glare under similar circumstances. With this group of
. ~
three Instruments we propose to evaluate any particular situation, interior as
well as exterior.
Byrnes: Thank you, Mr. Crouch. Is there any further discussion? If not,
I have one comment, namely, that in almost all of the papers concerning
capabilities of individuals, particularly on radar scopes, the subjects were in-
telligent, well motivated, untired, unbored subjects. The results with these
people are not totally comparable to the results obtained when a subject be-
comes tired and bored and "wants out." I would like to suggest that some of
these studies be carried to a point that will determine what factors retain their
importance when these other conditions come into play, because there may be
a difference.
This is the only comment I have to make on the symposium other than
.1 ~.1
J ~
to Inane tne program committee and Dr. Brown and our distinguished panel
for their participation, as well of course as the individuals who presented the
papers. I would also like to thank the members of the Committee who acted
as chairmen: Dr. Imus, Dr. Graham, and Colonels Gersoni-and Hill. And one
last piece of gratitude: This is my last meeting as Chairman of the Vision Com
· ~ _ ~ ~ ~ ~ r .~ . ~ ~ __:
Settee and 1 want to thank all of you for the support you nave given me curing
the several years that it has been my pleasure to serve as your Chairman. It
has been one of the really fine experiences of my life. Thank you very much.
203-
OCR for page 204
Representative terms from entire chapter:
visual displays
