Dome field of view scene extenders

In a vehicular simulator including a cockpit and visual system wherein the visual system includes a hollow, partial spherical screen 18 surrounding a cockpit 14, and wherein both the cockpit 14 and spherical screen 18 are supported by a base support structure 16 such that the nominal eye point 24 of a pilot operator sitting in the cockpit 14 is at or near the center of the spherical screen 18. Improvement apparatus is provided comprising a first base means or structure 38 for providing a selected increase of the distance between the nominal eye point 24 and base platform 16. A second spacing means 40 and 42 are also provided which maintains the same selected distance increase between the spherical center of the screen 18 and the base platform 16. Left and right curved screen panels 44 and 46 having a spherical surface with the same diameter as the spherical screen are provided to the left and right of cockpit 14 such that bottom edge of spherical screen 18 is increased in selected areas by the panels.

TECHNICAL FIELD 
This invention relates generally to visual systems for vehicle simulators 
and more particularly to apparatus for providing an extended field of view 
from an extreme eye point for visual systems using large spherically 
shaped panoramic screens. More particularly, this invention enlarges the 
display area with respect to the pilots downward field of view such that 
walkways or other simulator structures do not encroach upon the projected 
scene. 
BACKGROUND ART 
There are various types of scene generation systems which are used with 
modern vehicle or aircraft simulators and include motion film projection 
systems, camera model systems, and digital image generation systems. 
However, experience has shown that the more acceptable systems used today 
include camera model systems such as described in U.S. Pat. Nos. 
2,975,671; 3,643,345; 3,670,426 and 3,961,133. Another acceptable visual 
system for use with todays modern aircraft simulators is one that produces 
a computer generated image such as those systems described in U.S. Pat. 
Nos. 3,621,214; 3,826,864 and 3,961,133. 
Although the camera model system and the computer image generating system 
create or generate visual scenes by entirely different techniques, both of 
these systems may use one or more CRT's (cathode ray tubes) for 
presentations of the desired visual scene. In certain of these type 
systems, the CRT's are viewed directly, whereas in other systems the CRT's 
are viewed by means of optics such as beam splitters and/or mirrors. 
However, for certain types of applications, it has been found that the 
scene can better be viewed in certain simulation situations if the scene 
is projected onto a large panoramic or dome shaped screen surrounding (or 
partially surrounding) the simulator and observer. For these purposes, CRT 
projectors, video projectors and laser projector displays are particularly 
useful. 
The use of projected images on a panoramic screen has been found 
particularly useful in certain types of aircraft simulation. To achieve a 
completely realistic and panoramic view for an aircraft simulator, it will 
be appreciated that a substantially spherical screen with a pilots eye 
located at or near the screen's center would be necessary. Fortunately, 
since the aircraft is always "below" the pilot, there is a very limited 
FOV (field of view) in the downward direction. Consequently, most of the 
panoramic screens which use a spherical screen or dome configuration need 
not provide a complete spherical screen in the "hemisphere" "below" the 
pilot since the simulator pilot has unlimited view only in the top 
"hemisphere". That is, assuming that the pilot's eye is fixed at or near a 
point at the center of the panoramic or spherical screen, it is not 
necessary to provide a complete bottom "hemisphere" of the screen since 
the aircraft itself limits the pilot's vision or FOV in the downward 
direction. Consequently, it has been the practice with prior art spherical 
screens that only the portion of the bottom hemisphere of the screen which 
is in the FOV or line of sight from the nominal eye "point" is provided. 
That is, where the "aircraft" structure itself intersects a line of sight 
originating from the nominal eye point it is only necessary to provide 
these portions of the spherical screen which are visible. 
This approach has been successful for most uses, but as more and more 
effort is made to increase the realism of simulation systems, the 
limitations of this type of partial spherical screen have become apparent. 
For example, so long as the pilot does not move his head from the nominal 
eye point which is at or near the center of the spherical screen, he will 
have a full view provided by the visual system. However, such a fixed eye 
point for a pilot is not realistic since a pilot is continually turning 
and moving his head within the cockpit for better views and for close 
observation of his environment. Consequently, it has been found that when 
the simulator pilot moves his head to an extreme point within the cockpit 
such items as supports, platform walkways, and other simulator structures 
which are unnatural in the actual flight environment of an aircraft become 
apparent. 
A particularly objectionable feature is the sudden intrusion of the 
simulator platform walkway in the pilot's FOV when he moves his head to 
look down over the side of the aircraft. When this occurs, it is obvious 
that all the effort and trouble to present the illusion of a real flight 
scene to a pilot may be destroyed. Therefore, since it is desirable that 
any training situation closely simulate the real life situation, it is 
essential that for effective aircraft simulation that the pilot be free to 
move his head with the same freedom that he would have in an actual 
aircraft. Further, when the pilot moves his head to an extreme position he 
should only be presented with the desired simulated scene and not have the 
illusion destroyed by the intrusion of simulator structure. 
Therefore, it is an object of the present invention to provide a simple and 
inexpensive technique for providing a more complete panoramic view to a 
simulator pilot regardless of the position of the pilot's eye point. 
It is still another object of this invention to provide a more complete 
spherical screen for a simulator visual system which readily allows 
maintenance to the simulator but which still provides convenience for the 
simulator pilot in access to and egress from the simulator. 
It is yet another object of this invention to provide a more complete 
spherical visual screen without requiring complete redesign of the 
simulator support structure or the existing spherical screen. 
DISCLOSURE OF THE INVENTION 
Other objects and advantages will in part be obvious, and will in part 
appear hereinafter, and will be accomplished by the present invention 
which provides new apparatus for improving the display area of a spherical 
screen used in a projection visual system. The apparatus of this invention 
is an improvement for a vehicular simulator which includes a cockpit and a 
projection visual system. The visual system includes a hollow, partial 
spherical screen surrounding the cockpit, so that the inside surface of 
the hollow spherical screen provides the display area. The spherical 
screen and the cockpit are supported by a base platform so that the 
nominal eye point of an operator or student pilot in the cockpit is 
substantially at or near the center of the spherical screen. The spherical 
screen also includes left and right bottom edges with respect to the 
location of the cockpit. The improvement of this system comprises a 
spacing means for supporting the cockpit such that the distance between 
the nominal eye point of the cockpit and the base platform is increased a 
selected distance. A second spacing means also raises the display screen 
so that the distance between the spherical center of the screen and the 
base platform is also increased the selected distance. Left and right 
curved panels having a multiplicity of edges defined a selected shape. In 
a preferred embodiment, the panels have four edges and define a curved, 
yet substantially, rectangular shape. The curved surface of the panel 
defines a portion of the inside surface of a hollow sphere which has the 
same diameter as the diameter of the spherical screen. Selected edges of 
the left panel are formed to correspond with the left bottom edge of the 
spherical screen. In a like manner, the selected edges of the right panel 
are formed to correspond with the right bottom edge of the spherical 
screen. The left and right panels are then supported such that the display 
area of the spherical screen is increased so that an operator of the 
vehicle simulator will view the screen panels and any visual scene 
presented thereon when the operators eye point is moved from the nominal 
to the extreme left and right limits.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring now to FIG. 1, there is shown generally at 10 a diagrammatical 
front view of a prior art vehicular simulator system which includes a 
simulator 12 having a cockpit or controls section 14 supported by a base 
platform 16. The simulator 12 is enclosed by a partial spherical screen 18 
which is also supported at its bottom edges 20 and 22 by said base 
platform 16. The vehicle simulator 12 and the spherical screen 18 are 
supported on platform 16 such that the nominal eye point 24 of an operator 
(not shown) sitting in cockpit 14 of vehicle simulator 12 is at or near 
the center of the spherical screen 18. As shown, the bottom edges 20 and 
22 intersect the platform 16 thereby eliminating the bottommost portion of 
spherical screen 18. Also as is shown, a line of sight taken from nominal 
eye point 24 and represented on the left side by arrow line 26 and on the 
right side by arrow line 28 intersects spherical screen 18 at the 
intersection of bottom edges 22 and 20 with base platform 16. Thus, it 
will be appreciated that so long as the operator of the vehicular 
simulator maintains his eye point at the nominal eye point of the cockpit, 
platform 16 is out of view of the operator since the structure of the 
aircraft cockpit obscures the vision of the operator with respect to 
platform 16. Thus, so long as the operators eye point remains at the 
nominal eye point 24, a visual scene can be presented on the spherical 
screen without the simulated illusion of an acutal flight being destroyed 
by the intrusion of the simulator base platform 16. 
However, it will be appreciated that a competent pilot in an aircraft does 
not maintain his head in one position and does in fact move his head in 
all directions and to all areas possible within the cockpit to afford 
himself the best possible view above, to the sides, and below him at all 
times. Thus, it will be appreciated that at times the pilots eye point 
will be removed from the nominal eye point 24 and may in fact be at the 
left extreme eye point 30 or the right extreme eye point 32. In such 
instances, it will be appreciated that the pilots line of sight from 
extreme point 30 follows arrow line 34 on the left side and arrow line 36 
from extreme point 32 on the right side. Thus, as can be seen, if the 
pilot moves his head such that his eye point is at these extreme limits, 
his FOV is changed such that base platform 16 encroaches upon his view 
when he looks in a direction "beneath" the aircraft. Consequently, it will 
be appreciated that it would be desirable for the spherical screen to be 
extended such that a visual scene can be displayed on the screen so the 
scene would be visible even when the pilot has moved his eye point to an 
extreme eye point. With such an improvement, the flight illusion would not 
be destroyed by the intrusion of the base platform 16 upon the pilots 
vision. However, simply increasing the total area of the spherical screen 
would be costly, and for that matter unnecessary since only movement of 
the pilots head to the extreme left and right will reveal the platform. 
That is, movement of the pilots head in a forward or rearward extreme 
position does not result in any appreciable increase of his FOV (field of 
vision) in a downward direction as the rear of the aircraft and the front 
of the aircraft will continue to obscure his field of vision in these 
directions. 
Therefore, referring now to FIG. 2 there is shown a diagrammatical front 
view of an aircraft simulator system having a spherical screen visual 
system. Those elements of FIG. 2 which are the same as shown in FIG. 1 
retain the same reference numbers. As shown, vehicular simulator 12 having 
cockpit 14 is still surrounded by a spherical screen 18 supported by a 
base 16 such that the nominal eye point 24 of the operator in the cockpit 
is still at or near the center of the spherical screen. However, there is 
also included means or support structure 38 for increasing the distance of 
nominal eye point 24 a selected amount above platform 16. In a similar 
manner, left support 40 and right support 42 are also included to increase 
the distance of spherical screen 18 above base platform 16 the same 
amount. Also included is a left removable spherical surface panel 44 and a 
right removable spherical surface panel 46. Thus, as is shown, if the 
operator of the simulator now moves his eye point from the nominal point 
24 to one of the extreme eye points 30 or 32, his line of sight intersects 
one of these removable extensions 44 and 46 as is illustrated by line of 
sight lines 34 and 36. Thus, it will be appreciated that if a visual scene 
is presented on these removable sections 34 and 46 the base platform 16 
will not be in the simulator pilot's FOV when he moves his head to the 
extreme eye points, and thus the flight illusion will not be destroyed. At 
the same time, the panels may readily be removed thereby leaving the 
platform walkways clear for access to and egress from the vehicle 
simulator. 
Referring now to FIG. 3, there is shown a diagrammatical top view of the 
simulator spherical screen of FIG. 2. As shown in this Figure, the 
removable panels need not extend to the complete rear and aft portions of 
the simulator. It is unnecessary for removable panels 44 and 46 to extend 
to the fore and aft positions since the pilots FOV even when his eye point 
is moved to an extreme limit allowed by the cockpit, is still 
substantially obscured by the fore and aft portions of the aircraft such 
that he cannot look in a downward direction. Thus, it will be appreciated 
that it is only necessary that the removable side lower panels 44 and 46 
extend partially around the vehicular simulator. 
Referring now to FIGS. 4 and 5, there is shown a plot of the field of view 
of a pilot in a downward direction from the nominal eye point. Curved line 
48 represents the bottom edge of the window sill of the aircraft. As can 
be seen, the center line 50 represents the pilot looking in a forward 
direction as indicated by 0.degree. at the horizontal axis of the plot. As 
the pilot turns his head towards the rear of the aircraft, it can be seen 
that the window sill of the aircraft is plotted from the completely 
forward direction indicated at 0.degree. to the completely rearward 
direction indicated at 180.degree.. Thus, as can be seen, head motion of 
approximately 122.degree. to the left reveals tip 52 of the elevator 54 of 
the aircraft. Continued turning of the head would reveal the remainder of 
the elevator and would begin to pick up the tail section at about 
160.degree.. Rotation of the head to the right would also result in 
similar field of view and therefore need not be shown. The vertical axis 
of this graph represents the line of sight angle from the nominal eye 
point. Dashed line 56 represents the bottom left edge of the partial 
spherical screen. Line 60 represents the extension panel 42. Thus, it will 
be appreciated that since sill line 48 represents the extreme limit of the 
pilots field of view from the nominal eye point, the bottom edge 
represented by line 56 will not be visible and thus if the pilots eye 
point were maintained at this position dome extender 46 would not be 
necessary and the platform would never come into view. 
However, referring to FIG. 5, there is shown a plot of a pilots field of 
view who has moved his head to the extreme eye point 32. As can be seen, 
window sill line 48 has now crossed well below the bottom edge of the 
spherical screen represented by line 56 such that the removable panel 
extension 46 is now within view. However, it can also be seen that the 
removable panel 46 is sufficiently large such that the sill line 48 does 
not extend below the bottom edge of the removable panel as represented by 
line 60. It will further be appreciated that if the pilot were to move his 
head to the extreme limit on the right hand side, the right hand panel 44 
would provide a similar view. Thus, by extending the visual scene onto the 
removable panel it will be appreciated that the pilot will not be able to 
move his head to such an extreme position that the view presented on the 
spherical scene terminates and is replaced by platform 16 or other 
vehicular simulator structure. 
Thus, although the present invention has been described with respect to 
specific apparatus for providing a selected increase to a spherical 
display screen of a visual system, it is not intended that such specific 
references be considered limitations upon the scope of this invention 
except insofar as is set forth in the following claims.