A noncritical empirical detail-by-detail transformation of environmental information into flight display by purely physical methods characterizes the textured visual simulation as indiscernibly identical with the real scene. This method uses image storage, readout, image transformation, and graphic display to present a true color visual flight image to the pilot onboard aircraft in a purely electronic manner, employing analog-hybrid techniques

Gaertner, K.

English

NASA Technical Reports Server

24. A Proposal for Pre-Processing, Reduction, and Selection 
of Visual Information in Airborne Flight Simulation 
K.-P. GARTNER 
Every pilot who has flown on instruments 
knows the difficulty of learning to translate a 
number of indicators into a mental image to pro- 
vide him with the feeling of the attitude, level, 
and orientation of his aircraft. Even the most 
intimate familiarity with the cockpit instruments 
does not lend to the pilot the flight sensation 
which he knows from the familiar references of 
the horizon, the earth surface, and the sky. 
With the increasing level of aircraft complex- 
ity numerous technical sensors have been devel- 
oped to assist human perception, e.g., radar 
altimeters, interial platforms, etc. The informa- 
tion picked up by these sensors is presently in 
most cases still displayed on single independent 
instruments. In  critical situations, however, the 
pilot is overstrained by observing the wide vari- 
ity of instruments. The time he has availableto 
read all instruments relevant to a specific flight 
situation, frequently is not sufficient for reactions 
adequate to critical phases of the flight. Further- 
more the pilot is known to read preferably only 
those display parameters which he subjectively 
selects as important parameters. Thus he be- 
comes a limiting factor for the efficiency and 
safety of modern man-machine systems. 
Integrated displays comprise on a single screen 
information, which formerly has been obtained 
by checking a variety of different instruments. 
The introduction of flexible electronic displays 
made possible, on the one hand the technical 
verification of integrated flight displays, and on 
the other hand the presentation of complex image 
information. 
This development resulted in the need for the 
selection of the most suitable data to be pre- 
sented to the pilot in order to facilitate the 
Fo rschungsinstiMt fii r Anthopotechnik 
197 
interpretation of flight situations and to optimize 
the decision process with regard to the displayed 
information. 
This paper will give a contribution to the 
solution of this fundamental problem. 
For the purpose of onboard visual simulation 
the image contents of the out-of-the-window 
scene are to be simulated by technical means. 
The purpose is to produce artificially as a stimu- 
lus field on the eye retina a nearly true image of 
the heterogeneous textured outside world, in 
order to obtain a realistic impression of the 
simulated out-of-the-window scene. 
The entire scope of practically relevant com- 
plex situations could be covered by the so called 
“textured” visual flight simulation. This assumes 
an image generator of very high optical fidelity 
which, till date is not to be realized technically. 
I n  order to overcome this difficulty, the neces- 
sary information contents of the image can be 
reduced by means of a critical analysis of the 
information contents of the real world scene. This 
image analysis and the information reduction 
derived from this are essentially based on psy- 
chological rules and lead to flight scenes of 
characteristically modified, so-called “stylized” 
image contents: Coarse structures of the scene 
remain almost unchanged, while fine structures 
are simplified or modified. The described pro- 
cedure, i.e., simulate an artificial out-of-the- 
window scene by considering the special image 
contents, is referred to as “stylized visual flight 
simulation.” This method of visual simulation 
forms an alternative to the textured visual flight 
simulation mentioned earlier, which processes 
arbitrary empirical image contents without 
critical modification. 
https://ntrs.nasa.gov/search.jsp?R=19730001401 2020-03-17T07:19:31+00:00Z
198 SEVENTH CONFERENCE ON MANUAL CONTROL 
There are two tasks remaining in regard to 
application of stylized visual flight simulation: 
(1) Clarification as to the image stylization 
method. I n  this respect, primarily psychological 
aspects must be considered. 
(2) Examination of technical means for gen- 
eration of abstracted visual flight scenes. 
At first, images are examined as to their 
subjective information content. Objective and 
subjective image contents are visual image infor- 
mation carriers. Objective image contents appear 
as colorimetrieally measurable local color valence 
distributions. The subjective image contents 
constitute the essential object of the psycholog- 
ical perceptual process. With the perception of 
the out-of-the-window scene, certain image con- 
tent elements prove to be of predominant impor- 
tance for three-dimensional perception, so that 
these elements have to be reproduced with ahigh 
degree of fidelity in the stylized visual flight 
simulation. Other elements are of minor impor- 
tance and may, therefore, be resorted to for the 
technically necessary reduction in information 
capacity by abstraction, without making this 
process a disturbing factor noticed by- the pilot 
in the aircraft. The image content elements thus 
compiled and determined to be important consti- 
tute the psychological main components for the 
construction of stylized synthetic visual flight 
images. 
Figure 1 illustrates the difference between the 
textured and the stylized visual simulation. Both 
methods aim to create an artificial replica of the 
outside visual scene. The direct approach via a 
noncritical empirical detail-by-detail transforma- 
tion of the environmental information into the 
simulated image by purely physical methods 
characterizes the textured visual simulation, 
whose result would, ideally, be indiscernibly 
identical with the real scene. 
The generation of a stylized image starts from 
an analysis of the original image contents with 
Abstraction 
Mathematical Interrelationships 
Visual Simulation 
t Transmission Tezlurcd I Natural Surroundings 1 4  
FIGURE 1.-Schematic illustration of the 
stylized visual flight simulation. 
respect to  mathematical, mainly statistical regu- 
larities and to possibilities of simplifying abstrac- 
tions justified psychologically. The stylized 
image consequently is built up constructively 
from the analytical results. 
The analysis is compiled by questioning and 
observation of reactions of test persons. Evalua- 
tion of respective statements would require a 
quantitative perceptual psychology. However, a 
quantitative psychology is nonexistent, neither 
is the mechanism of perception understood. How- 
ever, a rough understanding of the perceptual 
process briefly described below is assumed to be 
achieved in perceptual psychology today. 
The information acquired by man through his 
sensors is not processed as an entity by the brain; 
due to a preprocessing in the sensory areas only 
a very limited flow of information is fed to the 
brain. Although this model of the perceptual 
process is not quantitatively understood as yet, 
it may be used to justify the stylization of 
images. 
With the knowledge of how preprocessing of 
visual information takes place such preprocess- 
ing, performed already during image generation, 
appears justified, which means that the eye 
receives already processed information and that 
the physiological preprocessing system becomes 
“unemployed.” 
Today, the central element of modern aircraft 
is the electronic computer, and it is the aim to 
accomplish also airborne visual simulation with 
computer systems. This requirement poses the 
question as to whether the information quantities 
provided by the flight scene can be processed by 
electronic means. This appears to be possible 
only with reduced image quality, i.e., image 
simplification or information quantity reduction, 
which provides for the desired technical feasibil- 
ity since it seems quite possible to produce 
simplified visual flight images with electronic 
computers. In  this case, however, the degree of 
realism must, at least, be so high that the objec- 
tive information content is sufficient to supply 
the pilot with the subjective information required 
by him. 
Therefore only those technical solutions ap- 
pear usable, which start from a comprehensive 
description of the original image contents and 
comprise a subsequent abstraction. The best 
VISUAL INFORMATION I N  AIRBORNE FLIGHT SIMULATION 199 
applicational future aspects for generators of 
stylized images result from the selection of suit- 
able flight missions. In  these image generators 
the simplification still acceptable has to be bal- 
anced against the psychological and operational 
fidelity requirements for visual flight scenes. 
Now the task remains to examine the technical 
possibilities for stylized visual simulation. The 
process of visual flight simulation consists of four 
subprocesses (ref. 1) : 
image storage-+readout+image transformation 
-+display 
The image storage contains the total informa- 
tion to be presented to the pilot during flight 
(fig. 2). From this, however, only a small fraction 
is read out. In  image transformation a true per- 
spective of the scene is created. 
The result of image transformation is a syn- 
thetic true-perspective and true-color visual 
flight image which is presented to the pilot on 
board the aircraft. 
At present, and presumably for a long time to 
come, only the cathode ray tube, preferably in 
the proven form as used in TV, is available for 
image displays. It is envisaged to generate in a 
purely electronic manner stylized visual flight 
images to be displayed by standard TV tech- 
niques. After close examination the analog- 
hybrid computer technique appears to be a very 
suitable means for the solution of the new task. 
As suggestions for solution of the simulation 
of landing approach, stylized flight images have 
been verified in a purely electronic manner, em- 
ploying the analog-hybrid technique (ref. 2). 
Figure 3 shows as an example the landing 
approach scene computed according to the raster 
method (ref. 3). Storage of the image content 
“runway” is achieved through applicable dimen- 
sioning of electronic computers, e.g., resistors. 
Such an airborne stylized visual simulation 
1 Image I I I I Image I I display I siorage readout transformation 
FIQIJRE 2.-The process of visual flight simulation. 
FIGURE 3.-TV screen photograph at a moment 
of a simulated landing approach. 
may be used for visibility zero-landing in the 
future. 
The novel methods described permit for the 
first time by means of an accessory system to 
the flight instruments of an aircraft the genera- 
tion of extremely well focused, high-contrast, 
color-true stylized images on standard TV screens 
with a very high freedom of maneuver. Future 
tendencies will presumably aim to utilize the 
control board computer of the aircraft instead 
of an independent accessory system, so that the 
following conclusion should be permissible. 
The visual flight simulation onboard an air- 
craft has up to now been a rather difficult and 
complex hardware problem. Through abstrac- 
tion, approaches become evident which suggest 
that visual simulation of out-of-the-window 
scenes, e.g., runway will become a software detail 
in the future and will thus cease to constitute a 
technical bottleneck within the field of visual 
flight displays. 
REFERENCES 
1. GARTNER, K.-P.; AND WERNICEE, J.: Verfahren der 
Sichtsimulation. Zufiihrung und Verarbeitung von 
Information durch den Menschen, Drei-Nationen- 
Tagung Mannheim, Sept. 1968-Verlag Krupinski, 
Mondorf bei Bonn, 1968. 
2. GARTNER, K.-P. : Stilisierte Flugsichtsimulation. Dis- 
sertation, Technische Universitat Berlin, 1970. 
3. WERNICKE, J. : Flugsichtsimulation mit Bildspeichern 
hoher Informationsdichte. Dissertation, Technische 
Universitat Berlin, 1969. 


A proposal for preprocessing, reduction, and selection of visual information in airborne flight simulation

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