Note: Descriptions are shown in the official language in which they were submitted.
FIELD O~ THE INVENTION
This invention relates to optical simulation apparatus,
and more particularly to an improvement in optical
tracking apparatus.
5 BACKGROUND OF THE INVENTION
In th~ training of military, commercial and other person-
nel, it is often desirable to make use of a target
tracking simulator in which the trainee must attempt to
keep a given target within the sights of the tracking
apparatus. In other applications the trainee must detect
and recognize realistic targets against a realistic back-
ground of excellent real world-like fidelity provided by
a medium such as a colour transparency. In such a target
tracking simulator or target recognition trainer, a
movable background is provided and a movable target can
be introduced into the scene by the operator of the simu-
lation apparatus, whether the simulator be under human or
automatic control. In the past, television screens have
been used to provide the background image, and the target
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has been introduced electronically into the scene by
"blanking out" a portion of the video background scene and
inserting an image of the target upon the video background
at a desired position, attitude and apparent distance.
One such technique is described in U. S. Patent No.
3,746,782 issued to Carl R. Driskell.
Because of the nature of television image generation, the
r~solution of video background images is not of the high-
est quality. The present invention makes use of a high
resolution film strip to generate the background image,
uses video techniques to generate the target image, and
then inserts the optical target image into the background
at the desired position and aspect by a novel technique.
Specifically, a cathode ray tube is used to illuminate the
background film image, and a video camera is used to ob~
serve the target and generate an electronic video signal
which "blanks out" the CRT background illumination at the
desired target position for the exact size of the target
image. The target image is then optically inserted at
this "blanked out" space for observation by the simulator
trainee. In this manner, the high resolution of film
background and foreground terrain are retained in the
target tracking simulator.
In a further improvement of the present invention, the
target image, or portions thereof, can be blanked out or
occulted by a display of "foreground" images, and in this
manner the target appears to the trainee observer to weave
in and out of the background and foreground in a most
realistic manner.
SUMMARY OF THE INVENTION
The present invention provides optical simulation appara-
tus using a target image superimposed upon a terrain film
transparency illuminated by a cathode ray tube raster
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blanked out in an area corresponding to the target image.
The superimposed image is presented to an observer for
target tracking. Additionally, the present invention pro-
vides means to occult all or a portion o-f the target image
by a foreground image.
Specifically, the present invention comprises a first
cathode ray tube which generates an illuminating first
raster, and a terrain image film transparency positioned
in front of and illuminated by that first raster. Means
for generating an image of a target are provided, as is a
first video camera for viewing that target image. Elec-
tronic apparatus is connected to the first video camera
and to the first cathode ray tube for blanking out a por-
tion of the first raster identical to the image outlined
by the target viewed by the first video camera. Optical
means for combining and superimposing the image of the
target upon the blanked-out portion of the first raster
makes it possible to present a composite view of the
target superimposed and inserted into the terrain image
for presentation to an observer.
The preferred embodiment of the present invention also
advantageously comprises a second cathode ray tube for
generating a second illuminating raster, and a foreground
image occulting film transparency positioned in front of
and illuminated by that second raster. In this improvement
there are additional optical means for presenting the
foreground occulted image for viewing by a second video
camera. There are also additional electronic means con-
nected to the means for generating the target image con-
nected to the second video camera for blanking out atleast a portion of the target identical to a superimposed
foreground occulting image viewed by the second video
camera.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a block diagram of a specific embodiment of
the present invention;
Figure 2 is a representation of a typical target image
generated by the apparatus of Figure 1;
Figure 3 is a representation of a typical background image
generated by the apparatus of Figure 1 as occulted by the
target image of Figure 2;
Figure 4 is a representation of a typical foreground
occulting film used in the apparatus of Figure 1;
Figure 5 is a representation of a target image occulted
by a portion of the foreground occulting image;
Figure 6 is a representation of the composite scene of a
target image, background and foreground images presented
to a trainee observer by the apparatus of Figure 1.
DESCRIPTION OF THE SPECIFIC EMBODIMENT
Figure 1 shows a block diagram of an embodiment of the
present invention. A programmable digital computer video
image generator 100, such as is well known to those skilled
in the digital and video arts, is provided to generate two
video signals. One of these signals is transmitted to a
cathode ray tube 102 to produce an image of a tar~et such
as the military tank shown in Figure 2. The generator 100
can be programmed so that the target image on the tube 102
changes attitude and apparent size as desired by the opera-
tor of the system. A second video signal is transmittedfrom the generator 100 to another cathode ray tube 104
for the programmable display of other effects, such as an
artillery blast from the tank's gun, or an explosion caused
by a gunnery hit upon the target. These images are com-
bined by a beam splitter 106 which transmits the combined
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target ana blast effects images 107 (Figure 2) along path108 to a first video camera 110. In this mode of opera-
tion the combined target images 107 can also be generated
in a purely optical manner, i.e. by means of a scanning
probe viewing a movable physical target.
The same combined target images 107 are also directed
through the beam splitter 106 along path 112 to another
beam splitter 114 which reflects the target images (here-
inafter called the target image 107) through a lens 116
for viewing by an observer trainee 118. The observer 118
also sees through the beam splitter 114 an image of ter-
rain which is produced by having a first cathode ray tube
120 generate an illuminating raster and having that illu-
mination projected by means of a lens 122 through a movable
film transparency 124 of the terrain through which the
target is to be moving. The film transparency 124 can be
advanced or moved backward by means not shown to simulate
observer vehicle motion with respect to the background.
Not all of the terrain image is directed toward the obser-
ver 118, however, since the first video camera 110 whose
output represents the target image 107 is connected to a
video mi~er and blanker 130. The construction of this
electronic apparatus is also well known to those skilled
in the video arts. As a result of the signal from the
video camera 110 the mixer and blanker apparatus 130, which
is connected to the input of the cathode ray tube 120,
blanks out a portion of the illuminating raster of that
- tube corresponding in size and position to the outline of
the target image. The result is that the terrain image
projected to the observer 118 contains, as shown in Figure
3 a blanked out portion 200, and upon this blanked out
portion is superimposed from path 112 an optical image of
the target. Thus the observer 118 has the advantage of
viewing a movable computer generated target image against
a high resolution film terrain background. A video
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synchronization signal generator 140 is connected to the
video camera 100 and the cathode ray tube 120 to keep the
images in synchronization.
A preferred embodimen~ of the present invention also has
the following features. In this arrangement a second
cathode ray tube 156 is provided to generate an illumina-
ting raster which is projected through a lens 158 to a
movable (by means not shown) film transparency 160 of fore-
ground images which are desired to occult the target image
as it moves across the terrain. The foreground-occulting
transparency 160 is made by reproducing a specific "fore~
ground" portion of the terrain transparency 124. A repxe-
sentation of such a foreground occulting film transparency
160 is sho~n in Figure 4. This foreground occulting image
is transmitted by means of a mirror 152 to the second
video camera 154. The video camera 154 is connected to
the mixer and blanking apparatus 130, and whenever the
video camera 154 scanning line detects an edge crossing of
the terrain occulting image 160 it appropriately turns "on"
or "off" the scanning beam of the video camera 110 so that
the target image is not complete, but illumination of that
portion of background film is as repxesented in the illus-
trationi~ of Figure 5. With the target image so modified
by the terrain occulting image the composite scene that the
observer 118 views is that of a target image occulting and
being occulted by portions of the terrain in a realistic
manner such as is illustrated in Figure 6. The synchroni-
zation generator 140 is also connected to the second
cathode ray tube 156 and the second video camera 154 to
keep all the generated images in synchronization. It will
also be understood that the terrain and terrain occulting
transparencies 124 and 160 are moved together in exact
synchronization in the operation of the apparatus. An
additional feature of this invention is that blast and
smoke effects appear particularly realistic since the video
camerallO will begin to "~ee through" the blast effects
generated by the image generator 100 as the smoke disperses
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and the intensity of the scanning beam of CRT 120 varies
from full "off" to full "on" in a gradual manner.
