Panoramic display with stationary display device and rotating support structure

The invention causes a panoramic view to be realistically displayed to a viewing audience. A fixed display device displays a portion of the panoramic view and a rotating support structure supports the viewing audience. The orientation of the portion of the panoramic view shown by the display device changes in coordination with the rotation of the support structure, while the viewing audience changes its viewing direction to continue looking at the display device. The characteristics of the system (in particular, the rotation of the support structure) are controlled so that the viewing audience is not conscious of the movement of the support structure, but thinks, instead, that the display device (and the displayed portion of the panoramic view) is moving about the support structure as the viewing audience changes its viewing direction. The invention can be implemented as a non-interactive system in which the system operates independently of the viewing audience. Alternatively, the invention can be implemented as an interactive system in which the orientation of the displayed portion of the panoramic view and the position of the support structure rotate in response to viewer input. The interactive system can be implemented either as a direct control system or a feedback control system.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the display of panoramic views and, in 
particular, to the display of panoramic views using a system that includes 
a stationary display device and a rotating viewer support structure to 
create the illusion that the display device moves around a viewing 
audience as the viewing audience changes viewing direction to view 
different parts of the panoramic view. 
2. Related Art 
Some video display systems simulate motion of the viewing audience. 
Generally, such video display systems include a display device and a 
support structure for supporting the viewing audience (which can be a 
single viewer or a group of viewers). Often, the display device and 
support structure interact in some way to enhance the motion simulation. 
In one type of motion simulation video display system, the display device 
(and the viewer's viewing direction) remains fixed while the support 
structure moves. A vehicle simulator (e.g., flight simulator) and a motion 
platform (e.g., certain theme park rides) are examples of such systems. 
The display device can show either linear or rotational motion. The 
support structure moves so as to transmit the sensation of inertial 
forces. The movement of the support structure is synchronized with the 
display device so that the motion sensations experienced by the viewing 
audience correspond to the video image being shown on the display device. 
However, in some situations, such as panoramic theaters, it is desirable 
to simulate motion of the viewing audience without transmitting physical 
sensations of movement of the support structure. This type of motion 
simulation video display system does not meet this need. 
In another type of motion simulation video display system, the support 
structure remains fixed while the display device (and a viewer's viewing 
direction) moves. Virtual reality display devices are examples of such 
systems (the stationary support structure being, for example, a chair, and 
the moving display device being, for example, headgear including a 
display). The display device can show either linear or rotational motion. 
The motion of the display device causes the viewer to perceive motion of 
the viewer relative to the displayed environment. However, it is desirable 
to produce simulated motion of a viewing audience by keeping the display 
device fixed while the support structure moves, since systems including a 
moving display device are typically more difficult and expensive to 
construct. 
SUMMARY OF THE INVENTION 
The invention causes a panoramic view to be realistically displayed to a 
viewing audience. A system according to the invention includes a display 
device for displaying a portion of the panoramic view and a support 
structure for supporting the viewing audience. The display device remains 
fixed while the support structure rotates. The orientation of the portion 
of the panoramic view shown by the display device changes in coordination 
with the rotation of the support structure (i.e., at the same rotational 
speed or speeds and about the same rotational axis or axes). The viewing 
audience changes its viewing direction to continue looking at the display 
device. The characteristics of the system (in particular, the rotation of 
the support structure) can be controlled so that the viewing audience is 
not conscious of the movement of the support structure (i.e., does not 
receive physical sensations of movement, such as sensations of inertial 
forces or vestibular sensations), but thinks, instead, that the display 
device (as well as the portion of the panoramic view shown by the display 
device) is moving about the support structure as the viewing audience 
changes its viewing direction. Since the system according to the invention 
includes a stationary display device and a rotating support structure, the 
system can be constructed more simply and cheaply than systems that 
include a rotating display device and a stationary support structure. 
The invention can be implemented as a non-interactive system in which the 
system operates independently of the viewing audience. For the 
non-interactive system to work as intended, the viewing audience 
continually changes viewing direction to keep looking at the display 
device as the support structure rotates. 
The invention can also be implemented as an interactive system in which the 
orientation of the displayed portion of the panoramic view and the 
position of the support structure rotate in response to viewer input. The 
interactive system can be implemented either as a direct control system or 
a feedback control system. In the direct control system, the viewing 
audience changes viewing direction to continue looking at the display 
device as the support structure rotates in response to viewer control. In 
the feedback control system, the orientation of the panoramic view on the 
display device and the support structure rotate in response to sensed 
changes in the viewer's viewing direction.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
FIGS. 1A and 1B are simplified representations of a system 100, 
illustrating operation of a system according to the invention. The system 
100 includes a display device 101 and a support structure 102. A viewing 
audience 103 (which can be a single viewer or a group or viewers) is 
supported by the support structure 102. A portion of a panoramic view 104 
(represented by a dashed circle in FIGS. 1A and 1B) is displayed on the 
display device 101. (As illustrated in FIGS. 1A and 1B, only that portion 
of the panoramic view 104 that intersects the display device 101 is 
displayed at any given time.) Herein, "panoramic view" is used to refer to 
a scene that encompasses all angular viewpoint orientations about a fixed 
point. 
In FIG. 1A, the viewing audience 103 has a viewing direction 105 
(illustrated by a directional arrow) such that the viewing audience 103 is 
looking at the display device 101. The support structure 102 is oriented 
so that the location C on the support structure 102 is in line with the 
viewing direction 105. The display device 101 displays a portion of the 
panoramic view 104 such that a location A within the panoramic view 104 is 
centered on a display screen of the display device 101. 
FIG. 1B illustrates the system 100 after the orientation of the portion of 
the panoramic view 104 shown on the display device 101 has been changed so 
that the location B within the panoramic view 104 is centered on the 
display screen of the display device 101. In FIG. 1B, the orientation of 
the panoramic view 104 has been rotated approximately 90.degree. from the 
orientation in FIG. 1A, as shown by the locations A and B. As the 
orientation of the panoramic view 104 changes (i.e., rotates), the support 
structure 102 is rotated. In FIG. 1B, the support structure 102 has been 
rotated approximately 90.degree. (the same amount by which the orientation 
of the panoramic view 104 has been rotated), as shown by the location C on 
the support structure 102. In order to continue looking at the display 
device 101, the viewing audience 103 must change its viewing direction 105 
with respect to the support structure 102 (i.e., keep the directional 
arrow pointing toward the display device 101). (The manner in which the 
viewing direction of the viewing audience 103 is changed can depend upon 
the particular embodiment of the support structure 102, as discussed 
further below). The support structure 102 and the orientation of the 
panoramic view 104 are rotated at the same speed, so that as the viewing 
audience 103 changes viewing direction, the viewing audience 103 sees the 
portion of the panoramic view 104 that would have been seen if the viewing 
audience 103 was actually in the environment of the panoramic scene and 
changed their viewing direction. 
An important aspect of the invention is that certain characteristics of the 
system 100 can be controlled so that the perception of inertial forces 
(i.e., centrifugal and coriolis forces) and vestibular sensations by the 
viewing audience 103 is inhibited. The viewing audience's movement to 
change viewing direction (with respect to the support structure 102) to 
keep looking at the display device 101 also inhibits these perceptions, 
both because of the movement of the viewing audience 103 and because the 
viewing audience 103 stays focused on a display screen that stays fixed 
with respect to the viewing audience 103 in the inertial reference frame. 
Since the perception of physical sensations associated with rotation of 
the support structure 102 are inhibited, the viewing audience 103 
perceives that the support structure 102 remains stationary and that the 
display device 101 moves around the viewing audience 103 as the viewing 
audience 103 changes its viewing direction. 
As indicated, certain characteristics of the system 100 can be controlled 
to inhibit the perception of the physical sensations associated with 
movement of the support structure 102. For example, the rotational 
velocity and acceleration of the support structure 102 is an important 
parameter that should be carefully controlled. The maximum allowable 
rotational velocity can depend on other physical characteristics of the 
system 100. However, based upon testing of systems according to the 
invention and upon prior research into the effects of rotation upon 
humans, it is believed that maintaining a constant velocity of 1 rpm or 
less should adequately inhibit the perception of rotation of the support 
structure 102. Further, the rotational acceleration is ideally maintained 
at zero; however, since the support structure 102 must be accelerated from 
rest to a constant operating speed, this acceleration is desirably kept as 
low as practicable, e.g., on the order of 10 rev/min.sup.2. 
Additionally, the distance from the viewing audience 103 to the display 
screen of the display device 101, the distance of the viewing audience 103 
from the center of rotation of the support structure 102, and the size (in 
particular, the width) of the display screen of the display device 101 can 
all be important, particularly as these quantities relate to each other 
and to the rotational speed of the support structure 102. Some of these 
quantities and their interrelationships are discussed, for instance, in a 
paper entitled "Spatial Correspondence in Motion Picture Display", by 
Michael Naimark, SPIE Vol. 462 Optics in Entertainment II (1984), the 
disclosure of which is incorporated by reference herein. For example, for 
a given display screen size, rate of rotation of the orientation of the 
panoramic view, and focal length of the lens used to obtain the panoramic 
view, there exists an optimum rate of rotation of the viewing audience, 
determined as discussed in the Naimark paper. 
To facilitate explanation of the invention, the illustration and discussion 
of the invention above with respect to FIGS. 1A and 1B is made for 
rotation of the support structure (and panoramic view) about a single 
axis. It is to be understood that rotation of the support structure and 
panoramic view can occur about any axis and, moreover, such rotation can 
occur about more than one axis simultaneously (e.g., two axes that are 
perpendicular to each other). The principles of the invention discussed 
above can apply to each axis about which rotation occurs. 
Since the system 100 includes a stationary display device 101 and a 
rotating support structure 102, the system 100 can be constructed more 
simply and cheaply than systems that include a rotating display device and 
a stationary support structure. This is particularly so for the wide angle 
display screens that are necessary to create the illusion of immersion in 
the environment of a panoramic view, due to the difficulty of coupling 
large rotating display screens accurately with projectors that can be used 
to produce the display of the panoramic view and the difficulty of 
conveying electrical power and signals for generating the display across a 
rotational bearing or bearings that would be necessary to allow the 
display screen to rotate. 
FIG. 2A is a block diagram of a system 200 according to one embodiment of 
the invention. The system 200 includes a display device 201, a support 
structure 202, a display control device 203, a support structure rotation 
device 204 and a synchronization device 205. The system 200 is a 
"non-interactive" system that operates independently of the viewing 
audience. The display device 201 displays a portion of a panoramic view, 
the orientation of which is rotated at a specified speed (e.g., 1 rpm). 
Rotation of the panoramic view is synchronized with rotation of the 
support structure 202. In order to appreciate the effects of the system 
200, the viewing audience must rotate their viewing direction with respect 
to the support structure 202 so as to compensate for the rotational motion 
of the support structure 202. 
The display device 201 can be any conventional display device, such as a 
conventional motion picture projector and screen, a computer including a 
display monitor, or a television. 
The display control device 203 includes a display controller and a display 
generator and can be implemented by any conventional such devices. The 
particular display controller and display generator used can depend upon 
the particular type of display device 201 that is used. For example, if 
the display device 201 is a computer display monitor, the display 
generator can be a VGA board. The display control device 203 can be 
implemented for example, as an appropriately programmed digital computer 
that causes the panoramic view on the display device 201 to be updated 
(from existing video image data--stored on, for example, a hard disk of 
the computer--representing the panoramic view at different orientations) 
at a rate that results in rotation of the orientation of the panoramic 
view at the specified speed. 
The support structure rotation device 204 can be any conventional device or 
devices, such as a motor or motors, that can drive the support structure 
202 to rotate. As suggested above, the support structure rotation device 
204 can be constructed to enable rotation of the support structure 202 
about more than one axis at a time. 
The synchronization device 205 synchronizes the display of the panoramic 
view on the display device 201 with the rotation of the support structure 
202. Since both of these rotations occur at the same speed (e.g., 1 rpm) 
about the same axis or axes, the synchronization device 205 can be, for 
example, a motor controller or controllers that control the motor or 
motors (support structure rotation device 204) to rotate the support 
structure 202 at the specified rotational speed or speeds. 
The support structure 202 can be embodied in any of a variety of ways. For 
example, the support structure 202 can be a chair, a platform, or a 
suspended support harness. It is anticipated that, for embodiments of the 
invention in which the support structure 202 rotates simultaneously about 
more than one axis, the support structure 202 should be embodied by a 
structure that securely holds the viewing audience in place (e.g., a chair 
or harness). 
In a particular embodiment of the system 200, the support structure 202 is 
a rotating platform. The rotating platform can be constructed in any of a 
number of ways that are known to those skilled in the art. The rotating 
platform can be operably coupled to the support structure rotation device 
204 (e.g., motor) using known techniques and apparatus. The rotating 
platform should be made large enough to support an anticipated number of 
viewers. An embodiment of the invention in which the support structure 202 
is a rotating platform can be used, for example, to implement a panoramic 
theater in which an audience gradually turns on the rotating platform to 
watch the sweeping of a panoramic view shown on the display device 201. 
When the invention is used to implement a large-scale panoramic display 
such as a panoramic theater, the display screen of the display device 101 
can be curved (e.g., the display screen can have a circular curvature) to 
enhance the panoramic effect. FIG. 2B is a perspective view of a panoramic 
theater according to the invention. (Components of the panoramic theater 
of FIG. 2B that are the same as components of the system 200 of FIG. 2A 
are designated by the same numerals.) 
In a particular embodiment of the invention in which the support structure 
202 is a circular rotating platform, the diameter of the rotating platform 
is 16 feet. The display screen of the display device 201 preferably has a 
circular curvature. The distance from the center of the rotating platform 
to the edges of the display screen of the display device 201 is also 16 
feet. (It is believed that the distance from the center of the rotating 
platform to the display device 201 should be at least eight feet from the 
closest point a viewer can come to the display screen for stereoscopic 
applications, and sixteen feet for monoscopic applications.) The width of 
the display screen (measured along the chord extending between ends of the 
display screen) of the display device 201 is, likewise, 16 feet, so that 
the displayed panoramic view subtends an angle of 60.degree.. The platform 
is rotated at a constant rotational velocity of 1 rpm. From rest, the 
platform is accelerated at constant acceleration to the constant operating 
velocity of 1 rpm over a period of 5 seconds. 
FIG. 3A is a block diagram of a system 300 according to another embodiment 
of the invention. The system 300 is an "interactive" system in which the 
orientation of the panoramic view on the display device 301 changes (i.e., 
rotates) and the support structure 302 rotates in response to a viewer's 
changes in viewing direction. Aside from changes in viewing direction, the 
viewer generally remains stationary on the support structure 302. The 
system 300 is a feedback control system in which the viewer indirectly 
controls operation of the system 300 by changing his viewing direction, 
which changes are sensed by the system 300 and used to control the display 
device 301 and the support structure 302. 
Similarly to the non-interactive system 200 (FIG. 2A), the system 300 
includes a display device 301, a support structure 302, a display control 
device 303, and a support structure rotation device 304. The display 
device 301 and display control device 303 can each be implemented as 
described above for the corresponding parts of the system 200 (i.e., 
display device 201 and display control device 203). 
The support structure 302 is preferably a support structure that is adapted 
to securely hold a single viewer in place during rotation of the support 
structure 302. The support structure 302 could be, for example, a chair or 
suspended support harness that is adapted to rotate. The rotating chair or 
harness can be constructed in any of a number of ways that are known to 
those skilled in the art. The support structure rotation device 304 can 
be, for example, a conventional servo motor that is operably connected, 
using apparatus and techniques well-known to those skilled in the art, to 
the support structure 302 so that the support structure rotation device 
304 can rotate the support structure 302. The support structure 302 and 
support structure rotation device 304 can be adapted to rotate 
simultaneously about more than one axis, as described above. 
The sensor 306 senses changes in the viewer's viewing direction. Any sensor 
that can accurately sense changes in viewing direction (i.e., rotational 
movement of the viewer's gaze about an axis that is substantially centered 
along and parallel to the length of a viewer's body) can be used. There 
are a number of such sensors that can be mounted on headgear that is worn 
on the viewer's head. For example, a Polhemus sensor, a well-known 
magnetic sensor used in many so-called virtual reality applications that 
sense all three components of rotational motion and all three components 
of translational motion, can be used. Or, a gyroscopic sensor (again, 
mounted on the head of the viewer and capable of sensing all three 
components of rotational motion) including a piezoelectric motion 
transducer could be used. Or, an optical sensor (e.g., infrared sensor) 
could be used to sense the relative positions of the pupils and, possibly, 
the sclera of the eyes to discern the angular orientation of the viewer's 
head. For some applications, sensors that sense scapular (shoulder) 
pressure and motion could be used. However, scapular motion sensors are 
limited to applications in which the viewer must move his shoulders with 
movement of his head when changing viewing direction. 
The sensor 306 transmits an electrical signal having a magnitude that is 
proportional to the viewing direction of the viewer's head. A reference 
generator 308 transmits a reference electrical signal having a magnitude 
representing a reference position (e.g., looking straight ahead at the 
display device 301) of the viewer's head. These electrical signals are 
input to a comparator 307 which produces an output signal (error signal) 
that has a magnitude that represents the difference between the magnitudes 
of the input signals. This error signal indicates the amount by which the 
viewer has turned his head so that the viewer is no longer looking at the 
display device 301. 
The error signal from the comparator 307 is input to a time-domain signal 
processor 305. The time-domain signal processor 305 can be implemented 
using techniques and apparatus known to those skilled in the art of 
servo-operated mechanical systems to produce two control signals having 
the following desired characteristics. The time-domain signal processor 
305 can be implemented to produce analog or digital control signals as 
desired. 
The time-domain signal processor 305 produces a first control signal that 
is used to control rotation (velocity and acceleration) of the support 
structure 302. The first control signal should cause the support structure 
302 to be re-positioned rapidly enough to adequately track changes in the 
viewer's viewing direction. However, the first control signal should also 
be smooth (i.e., without discontinuities) so that, when a change in the 
position of the support structure 302 is required, the change can be 
accomplished without jerkiness, so that the kinaesthetic sensation of 
movement felt by the viewer is minimized. The first control signal is also 
produced so as to minimize acceleration of the support structure 302 
consistent with the goal of repositioning the support structure 302 
rapidly, again to minimize the kinaesthetic sensation of movement. 
Additionally, the first control signal should respond only to changes in 
viewing direction above a minimum threshold. 
The time-domain signal processor 305 produces a second control signal that 
is used to control the content of the display device 301. The second 
control signal causes the display control device 303 to update the display 
on the display device 301 so as to track the change in the viewer's 
viewing direction so that the viewer sees the portion of the panoramic 
view that would be seen if the viewer was actually in the environment of 
the panoramic scene. Using the sensed position of the viewer's viewing 
direction, this can easily be done using video image data that correlates 
portions of the panoramic view to viewing directions. Alternatively, a 
conventional rotational position sensor can be mounted on the support 
structure 302, and the sensed position of the support structure 302 used 
to generate the second control signal. 
Additionally, the time-domain signal processor 305 can produce the first 
and second time derivatives of the change in the viewer's viewing 
direction. These derivatives can be used by the display control device 
303, as known by those skilled in the art, to control image 
characteristics such as blur and foreshortening. 
The first control signal output from the time-domain signal processor 305 
can be amplified by a conventional amplifier 309 which produces a support 
structure control signal that is used to drive the support structure 
rotation device 304. The second control signal output from the time-domain 
signal processor 305 is input to the display control device 303 which 
produces a display control signal that is used to control the display 
device 301. 
In operation of the system 300, as the viewer turns his head (i.e., changes 
viewing direction), the system 300 senses the head movement and both 
rotates the support structure 302 and updates the panoramic view so that 
the viewer continues to see the display device 301 that now shows a 
portion of the panoramic view that has an orientation that is rotated from 
the orientation of the originally displayed portion of the panoramic view 
by an amount equal to the amount that the viewer rotated his head. Thus, 
the viewer perceives that, as he turns his head, a window on to the 
panoramic view (the display device 301) has rotated about him to show 
another portion of the panoramic view. For example, if the viewer turns 
his head 45.degree. to the right, the support structure 302 rotates 
45.degree. to the left so that the viewer continues to look at the display 
device 301. Simultaneously, the orientation of the panoramic view shown on 
the display device 301 rotates 45.degree. to the right so that the viewer 
sees the view that would be seen if the full panoramic scene was visible 
around the viewer and the viewer had rotated his head 45.degree. from the 
initial position. 
As in the non-interactive system 200 (FIG. 2A), the support structure 302 
of the interactive system 300 can be rotated so as to minimize the 
physical sensation of movement of the support structure 302 consistent 
with the goal of rapidly turning the viewer so that the viewer continues 
to look at the display device 301. Such physical sensation can be 
minimized in the manner and for the reasons described above. However, 
since the viewer can change his viewing direction relatively rapidly, in 
practice, there can be an unavoidable trade-off between these two goals. 
It should be noted, though, that for embodiments of the invention in which 
the viewer controls the rotation of the support structure and panoramic 
view, rotational velocities and accelerations of greater magnitudes can be 
tolerated by the viewer without perception of motion sensations. Thus, for 
example, the above-discussed limitation of 1 rpm for rotational velocity 
may not be applicable in these embodiments. 
FIG. 3B is a block diagram of an "interactive" system 320 according to yet 
another embodiment of the invention. The system 320 includes a display 
device 301, a support structure 302, a display control device 303, a 
support structure rotation device 304 and an amplifier 309 that are the 
same as the like-numbered components of the system 300 (FIG. 3A). 
In contrast to the system 300, the system 320 is a direct control system in 
which the viewer directly controls operation of the system 320 through use 
of a support structure position control device 312 to operate the support 
structure 302. In response to input from the viewer, the support structure 
control device 312 produces a signal that is amplified by the amplifier 
309, which amplified signal is used to drive the support structure 
rotating device 304 as described above with respect to FIG. 3A. The 
support structure control device 312 can be any conventional control 
device such as, for example, a push button, lever switch or potentiometer. 
A support structure position sensor 311 is attached to the support 
structure 302 and generates a signal that corresponds to the rotational 
position of the support structure 302. The support structure position 
sensor 311 can be any conventional rotational position sensor such as a 
mechanical potentiometer or an optical shaft encoder. The generated signal 
from the support structure position sensor 311 is similar to the second 
control signal produced by the time-domain signal processor 305 of the 
system 300 (FIG. 3A) and is input to the display generator 303 as 
previously described, so that the viewer sees the portion of the panoramic 
display which would be seen if the viewer was actually in the environment 
of the panoramic scene and looking with the orientation as sensed by the 
support structure position sensor 311. Though not shown in FIG. 3B, the 
sensed position can also be fed back to a comparator that is part of the 
support structure position control device 312 and compared to a reference 
signal that represents the commanded position of the support structure 
302, thus implementing a feedback control system for controlling the 
position of the support structure 302. The viewer senses that, rather than 
causing the motion of the support structure 302, he is causing an opposite 
movement of a viewing window represented by the display device 301. The 
viewer turns his head so as to maintain his direction of gaze at the 
display device 301, and by so doing maintains his head in a stable 
position with respect to the inertial reference frame. This prevents 
unwanted inertial sensations and gives the viewer the sense that he is in 
control of the motion of the viewing window. 
FIG. 3C is a block diagram of an "interactive" system 330 according to 
still another embodiment of the invention. The system 330 includes a 
display device 301, a support structure 302, a display control device 303 
and a support structure position sensor 311 that are the same as the 
like-numbered components of the system 320 (FIG. 3B). Like the system 320, 
the system 330 is a direct control system. However, the system 330 differs 
from the system 320 in the manner in which the viewer controls the system. 
In the system 330 the viewer supplies the motive force (rather than using 
a support structure position control device 312 as in the system 320) to 
cause the support structure 302 to rotate. For example, if the support 
structure 302 is a chair, the viewer can push with his legs to cause the 
chair to rotate. The viewer senses that, by using his body, he can cause 
the viewing window represented by the display device 301 to rotate about 
him. 
Various embodiments of the invention have been described. The descriptions 
are intended to be illustrative, not limitative. Thus, it will be apparent 
to one skilled in the art that certain modifications may be made to the 
invention as described above without departing from the scope of the 
claims set out below.