THREE-DIMENSIONAL VIDEO SYSTEM

Abstract: The illusion of three-dimensional images is achieved by having a first video camera (10) oriented to view the subject (20) from one point of origin, a second video camera (12) oriented to view the subject (20) from another point of origin, a switching device (14) for alternately coupling the output signal from one of the two cameras to an output terminal at a rate within a range between 4 and 30 times per second and a display device (18) including a viewing surface for converting the output terminal into a visual display on the viewing surface.

Description: THREE-DIMENSIONAL VIDEO SYSTEM Background of the Invention I. Field of the Invention The present invention relates to apparatus and methods pertaining to three-dimensional display systems. II- Description of the Prior Art Stereoscopic films are known. Such films may comprise a double row of left and right images, or a single row of alter¬ nate left and right images which have been photographed from horizontally aligned left and right points of origin. Prior art three-dimensional systems typically operate upon the principle that left and right eye images must remain separated in order to create a stereoscopic effect. These "binocular" systems there¬ fore employ red and green colored glasses, mechanical viewers, or polarized filters in order to assure that only the left eye images reach the left eye and the right eye images reach the right eye. Although results from such systems can be spectacu¬ lar, the need for extraneous viewing equipment has led to the commercial demise of all such systems. Furthermore, none of these systems is capable of displaying a three-dimensional illu¬ sion using simply a standard home television receiver. The history of prior art three-dimensional systems occasionally includes mention of a "monocular" or "σyclopean" system, in which alternately left and right images were rapidly displayed in an effort to create a three-dimensional illusion through "fusion" of the two images. Complicated multi-film pro¬ jectors were utilized to implement such systems, left and right images were taken simultaneously on a single film strip to facil ¬ itate registration, and speeds of 48 frames per second were tried. But none of these systems achieved any significant com ¬ mercial success and none was deemed capable of displaying a three-dimensional illusion using simply a standard home televi ¬ sion camera. Moreover, even at a reduced rate of display wherein the stereoscopic effect is increased, the inventors have deter- mined that the appearance of jumping between successive images renders an unsatisfactory result. Each of the prior art systems known to the. inventors is believed to have failed primarily because the system was compli¬ cated. To succeed, a three-dimensional system must be simple. The system must be capable of use with a standard home television receiver - without any modification to the receiver. Accordingly, an object of the subject invention is to provide a display system which exhibits a three-dimensional illu¬ sion using a standard, unmodified home television receiver as a means for display. Another object of the subject invention is to provide a display system which exhibits a three-dimensional illusion in which a representation of the images to be displayed is recorded on a standard video tape. Another object of the present invention is to provide a display system which exhibits a three-dimensional illusion in which the images to be displayed are either created and/or stored in the memory bank of a computer of the type employed in video games which are today becoming commercially popular. Additional objects and advantages of the invention will e set forth in part in the description which follows and in part will be obvious from the description, or may be learned by prac¬ tice of the invention. The objects and advantages of the inven¬ tion may be realized and obtained by means of the instrumentali¬ ties and combinations particularly pointed out in the appended claims. Summary of the Invention To achieve the foregoing objects, and in accordance with the purposes of the invention as embodied and broadly described herein, an apparatus for achieving a three-dimensional illusion of a subject is provided which comprises means for gen¬ erating electronic signals which represent the image of a subject as viewed alternately first from one point of origin and then, time displaced, from another point of origin at a rate within a range of 4 to 30 individual viewings per second; and means for sequentially displaying the images represented by those elec¬ tronic signals. In a more narrow sense, the invention comprises a first video camera; a second video camera; an output terminal; means for providing to the first video camera the image of the subject as viewed from one point of origin and providing to the second video camera the image of the subject as viewed from another point of origin; switching means for coupling the output signals one at a time from the first and second video cameras alternately to the output terminal at a rate within a range of 4 and 30 times per second; and display means including a viewing surface for converting the output signals at the output terminal into a visual display on the viewing surface. Since the display means is converting a standard video signal, the display means may take on the form of a standard home television receiver without any modification. A displacement of the two cameras at a distance less than the 65mm standard interocular distance is presently pre¬ ferred, and preferably this displacement is on the order of 10-15 mm. In addition, it is preferable that the switching means for alternately coupling the output signal from each of the first and second video cameras to the output terminal operate at a rate within a range of 6 to 15 times per second, and most preferably at a range about 8 times per second. Although first and second video cameras are contem¬ plated, the subject invention is also intended to expressly include the utilization of a computer to generate and/or store data representing images comparable to those viewed by the above- mentioned first and second video cameras. By storing such images in a memory bank, the images may be played back at will to create a three-dimensional effect upon a display means, such as a stan- dard cathode ray tube utilized in video -games. Accordingly, using the subject invention, the display on a cathode ray tube of such games can generate a three-dimensional illusion, thereby even further enhancing the enjoyment and commercial success of such games . Brief Description of the Drawings The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrates a pre ¬ ferred embodiment of the invention and, together with the general description of the invention given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. Fig. 1 is a block diagram of a system incorporating the features of the subject invention; Fig. 2 illustrates the position of two video cameras in accordance with a preferred embodiment of the invention; Fig. 3 illustrates a side view of the camera position shown in Fig. 2; Fig. 4 illustrates a front view of the camera position illustrated in Fig. 2; Fig. 5 illustrates a particular mechanism for achieving the camera position illustrated in Figs. 2-4; Fig. 6 is a perspective view of the platform illus- trated in Fig. 5 ; Fig. 7 illustrates a bracket shown in Figs. 5 and 6; Fig. 8 is a block diagram of a dual video camera system incorporating the features of the subject invention; and Fig . 9 is a block diagram of a computer incorporating th* 2 features of the subject invention. Detailed Description Subject invention comprises methods and apparatus for presenting images which are perceived by the viewer to be three- dimensional when viewed with the unaided eye. The viewing mecha- nisms may be television and the images may be generated by tele¬ vision cameras. In addition, the images may be generated by a computer and/or stored in a computer memory and generated by tel¬ evision techniques on a video screen used in connection with dis¬ play devices such as video games. In accordance with the present invention images of a subject as viewed alternatively first from one point of origin and then, time displaced, from another point of origin at a rate within a range of 4 to 30 changes between points of origin per second are displayed on a viewing mechanism. For example, in Fig. 1 there is illustrated a first video camera 10, a second video camera 12, a switching network 14, a control oscillator 16, and a television monitor 18. The output of cameras 10 and 12 is selectively coupled by switching network 14 to monitor 18, with monitor 18 displaying the image viewed by that camera 10 or 12 which is, at the moment under consideration, connected by switch¬ ing network 14 to the input of monitor 18. The frequency of operation of switching network 14 is governed by the output of control oscillator 16. As shown in Fig. 1, cameras 10 and 12 are both directed at a subject 20. Camera 10 views subject 20 from a point of ori¬ gin 22 which, for purposes of this invention, is generally and broadly defined as the optical axis of the input lens of camera 10. Camera 12 views subject 20 from another, different, point of origin 24 defined by the optical axis of the input lens of camera 12. By alternately connecting the outputs of cameras 10 and 12 to the input of monitor 18, through the operation of switching network 14, monitor 18 displays images of subject 20 as viewed alternately first from one point of origin 22 and then, time dis¬ placed, from another, different, point of origin 24. The rate of changes appearing at monitor 18 between point of origin 22 and point of origin 24 is governed by opera¬ tion of control oscillator 16. In accordance with the subject invention, this rate of change is within a range of 4 to 30 changes between points of origin per second. Preferably, this rate of change is between 6 and 15 changes per second, and most preferably this rate of change is about 8 changes per second. For example, when operating at a rate of 8 changes per second, every 0.125 seconds switching network 14 operates to switch moni¬ tor 18 from one to the other of cameras 10 and 12. Thus, an out¬ put control signal from control oscillator 16 having a frequency of 8 cycles per second may ideally be employed to govern opera¬ tion of switching network 14. As the rate of change between points of origin approaches 30 changes per second, a three-dimen¬ sional illusion presented on the viewing surface of monitor 18, namely the surface of the cathode ray tube of monitor 18, dimin¬ ishes. Above a rate of approximately 30 changes between points of origin per second, the two images become fused into one, and the three-dimensional affect is effectively lost. Below 4 changes per second, the two separate images from each point of origin are seen as simply two separate images. The preferred rate of operation is around 8 changes per second, and good results occur between 6 and 15 changes per second. ' Although a stereoscopic effect is achieved by simply operating the system of Fig. 1 at a rate within a range of 4 to 30 changes between points of origin per second, the operation of Fig. 1 is substantially enhanced by vertically displacing the points of origin of cameras 10 and 12 with respect to one another. Preferably, the vertical displacement takes the form of a vertical alignment of one point of origin directly over the other, without any horizontal displacement therebetween. Fur¬ thermore, although stereoscopic effect is increased by maximizing the distance between the points of origin of cameras 10 and 12, more precise registration of the images produced by cameras 10 and 12 is achieved by displacing the points of origin of cameras 10 and 12 from one another at a distance less than the normal interocular distance of a human being, namely less than approxi- mately 65 millimeters. Most preferably the distance between the points of origin is chosen to be within the range of 10 to 15 millimeters. The vertical displacement of the points of origin can be achieved in accordance with the arrangement illustrated in Figs. 2, 3, and 4 wherein cameras 10 and 12 are shown arranged side-by-side with optical axis 22 and 24 of cameras 10 and 12, respectively, substantially parallel to one another and separated a distance 26 which is less than 65 millimeters, and preferably on the order of 10 to 15 millimeters. Camera 10 is aligned to receive optical images reflected from a one hundred percent reflecting mirror 28, while camera 12 is aligned to receive video images through a two-way mirror 30. The surfaces of mirrors 28 and 30 are positioned parallel to one another and at a 45 degree angle to the optical axes 22 and 24 of cameras 10 and 12. How- ever, as is best shown in Figs. 3 and 4, optical axis 22 is loca¬ ted at a distance 32 above optical axis 24. Accordingly, optical axes of cameras 10 and 12 lie effectively in the same vertical plane, but lie in horizontal planes vertically separated from one another a distance 32. Preferably this separation distance is less than 65 millimeters and most preferably is within the range of 10 to 15 millimeters. Although the human eyes, which represent the points of origin of images viewed by a human being, are horizontally aligned with respect to one another, the points of origin as illustratively shown in Figs. 2 through 4, results in a three- dimensional image in which undesirable motional effect of the resulting display is decreased over the motional effect achieved with horizontal orientation of the points of origin. For reasons not yet fully understood, motion due to vertical parallax which is observed in a vertical point of origin orientation system is less disturbing than motion due to horizontal parallax observed in a horizontal point of origin orientation system. One simple example of an apparatus for satisfactorily mounting cameras 10 and 12 in a vertical point of origin orienta¬ tion is shown in Figs. 5 and 6 as utilizing a tripod head 34. Tripod head 34 includes first plate 36, second plate 38, and third plate 40. Camera 12 is anchored directly to first plate 36. Second plate 38 is spring loaded onto first plate 36 and held in position by thumb screws 42. Plate 38 can be moved vertically with respect to plate 36 by operation of thumb screws 42. Plate 38 can also be tilted about an axis along the optical axis of camera 10 and/or about a horizontal axis perpendicular to optical axis 26 of camera 10. Third plate 40 is mounted by center located swivel pin 44 to second plate 38 and moves against the operation of spring loaded thumb screws 46. As is more clearly shown in Fig. 7, thumb screws 46 each include a right angle bracket 48, a screw 50 and a spring 52. One leg of each bracket 48 is attached to second plate 38, and the second leg of each bracket 48 includes an opening to receive screw 50. Spring 52 is located between the second leg of each bracket end of leg 48_ and a side wall 54 of third plate 40. Accordingly, the adjustment of screws 50 in brackets 46 provide for controlled motion of plate 40 about a vertical axis concentric with the axis of swivel pin 44. The schematic block diagram of Fig. 8 shows one illus- trative example of an electronic circuit suitable for use in con¬ nection with the subject invention. In Fig. 8 the video output of cameras 10 and 12 is coupled to the input of amplifiers 50 and 52, respectively. The output of amplifiers 50 and 52 is coupled ■ ^T E o":ι ' > V...- to a common output terminal 54. Amplifiers 50 and 52 each have enable terminals 56 and 58, respectively. The Q ∑ output of flip- flop 60 is coupled to enable terminal 56 of amplifier 50 whereas the inverse output Q, of flip-flop 60 is coupled to enable ter i- nal 58 of amplifier 52. As set forth above, the vertical align¬ ment of the video input to cameras 10 and 12 is achieved, for example, by using the apparatus illustrated in Figs. 2-7, or by using an apparatus optically similar thereto, to provide to cam ¬ era 10 the image of the subject 20 (Fig. 1) as viewed from one point of origin and for providing to the camera 12 the image of subject 20 as viewed from another point of origin. Amplifiers 50 and 52, flip-flop 60, and control oscil¬ lator 16, provide means for alternately coupling the output sig¬ nal from each of the video cameras 10 and 12 one at a time to output terminal 54 at a rate within a range between 4 and 30 times per second. Output terminal 54 may, for example, be cou¬ pled to the input of monitor 18 (Fig. 1) so that monitor 18 pro¬ vides a display mechanism for converting the output signals from cameras 10 and 12 at terminal 54 into a visual display. Although optical elements such as mirrors are illus¬ trated as being utilized in the arrangement shown in Figs. 2-4, it is to be understood that a lens system, a prism system, or any equivalent optical arrangement is to be deemed equivalent to the specific mirror system illustrated. Moreover, if the cameras employed are small enough, it is possible that the lenses may be set at the appropriate optical interrelationship with respect to one another, without any intervening apparatus other than the lenses of the cameras themselves. The lenses of the cameras themselves are, in such instances, the means for providing the first camera with the image of the subject as viewed from one point of origin and the second camera with the image of the sub¬ ject as viewed from another point of origin. Each camera 10 and 12 is supplied a synchronizing sig¬ nal. Usually these signals are identical, but special effects can be generated if these signals are adjusted for different times relative to each other. When using equal and normal syn¬ chronization pulses of 60 hertz to give a 30 hertz total framing rate since the interlacing of two half frames is required to give a full frame, using every other synchronizing pulse to operate flip-flop 60, would result in whole pictures from cameras 10 and 12 being interlaced alternatively at output termainal 54. The number of synchronizing pulses transmitted between each input pulse to flip-flop 60 thereby determines the rate of change of points of origin available at output terminal 54. The number of synchronizing pulses transmitted between each input pulse to flip-flop 60 need not be the same. This can result in the number of full frames from each camera not being equal. This can also generate special effects. However, typi¬ cally, an equal number of frames from each of cameras 10 and 12 is chosen to be delivered to output terminal 54 between input pulses to flip-flop 60. The pattern followed preferably is N full frames from camera 10 then N full frames from camera 12. The mixed output is thus a series of video signals from pictures alternately from camera 10 and camera 12. These signals are then transmitted just like any ordinary single camera video signal. The camera fields of view are adjusted so as to place the images in registry at some plane in the field of view of the cameras. This necessitates adjustment of the cameras so that the parallax seen on a viewing television screen is zero at some dis¬ tance from the cameras. Adjustment of the cameras can easily be made while viewing the resultant images on the television. The correct adjustment is sensed when there is no motion of objects between images recorded by camera 10 and camera 12 at the desired distance. The mind of the viewer will then sense a depth to the composite camera 10 and 12 views. The preferred adjustment of the circuit of Fig. 8 is to select two full frames of each camera 10 and 12 prior to switch- ing of flip-flop 60. The resulting frame switching is thus 15 hertz between cameras 10 and 12. Viewing the composite picture for single frames at a rate of 30 hertz is the extreme upper limit, and in fact under some circumstances appears too fast for best impression of depth. The viewing of three frames of pic- tures from each camera at a rate of change of 10 hertz has been observed as being as satisfactory as the utilization of two frames from each camera 10 and 12 prior to changeover. Increas¬ ing the number of frames to four prior to a change results in a 7.5 hertz rate which also has been observed to provide comfortable three-dimensional viewing. A scan rate of sub-multiples of 60 hertz is dictated by the standardization of commercial television under 60 hertz line frequency in the United States. If a closed circuit system is used independently of the commercial television sys¬ tem, such as in a computerized video game, then any frequency in the range from about 4 to 30 hertz, and most preferably in the range of 6 to 15 hertz for the operation of flip-flop 60 will be satisfactory. Furthermore, it is to be understood that the principles of the present invention may be achieved in connection with a television display mechanism, without the use of video cameras. For example, visual computer games which are well known today include a cathode ray tube monitor 70 as shown in Fig. 9, the display on which is governed by operation of a microprocessor 72. Microprocessor 72, as is well-known to those skilled in the art, retrieves stored display data from a memory such as read only memory 74 and causes an image represented by the stored data to appear on the display screen of monitor 70. The operation of microprocessor 72 is controlled by a clocking mechanism 76. In present day video games, the resultant images por¬ tray a flat two dimensional illusion. However, if data repre¬ senting images of a subject as viewed alternately from first one point of origin and then, time displaced, from another point of origin were stored in ROM 74 and display by microprocessor 72 on monitor 70 at a rate within a range of 4 to 30 individual view- ings per second, a standard video game could be made to present a three-dimensional illusion. As is true when employing the sub- ject invention in connection with standard television cameras, it is preferable that the points of origin of the data stored in ROM 74 be vertically displaced with respect to one another and that the data represent the subject as viewed from points of origin displaced from one another at a distance less than 65 mm, and preferably in the range of 10-15 mm. Furthermore, it is prefer¬ able that the range of operation be between 6 and 15 changes in points of origin per second, and most preferably about 8. c:τι The techniques of the subject invention basically uti ¬ lize the eye and brain's ability to perceive stereopsis through the merging of two or more separate images in a manner which may be referred as cyclopean perception. The key requirement is the need to give the brain two separate images. Conventionally the two images are received simultaneously through separate parallel inputs —the two eyes— and mixed in the brain. However, the subject invention presents the two images sequentially and the brain mixes the images using a short term memory storage capacity inherent within the brain. Since both eyes receive the same input, no specific glasses are required. In fact, closing one eye makes no change in the perceived depth. The image can be seen by people with only one eye and can also be seen, trans¬ mitted, and recorded with single-camera television systems. If the camera zooms in to a reduced portion of the image, and then pans across the scene, a very strong illusion of real movement is created. Similarly, zooming in to a small portion of the image does not change the effect and the apparent motion into the scene is enhanced. One of the basic critical ingredients to achieving stereoscopic effect is timing the presentation of the images to the eyes sufficiently fast so that the brain does not consciously perceive two separate images, but sufficiently slow so that the subconscious perception of two images is achieved. The ideal and critical range is between approximately four images per second and 30 images per second, with the preferred range between 6 and 15 images per second, and ideally on the order of about 8 changes per second. Moreover, registration difficulties are minimized by vertical orientation of the point of origin of the two images, and by reducing the distance between the points of origin to less than normal interocular distance, preferably on the order of 10 to 15 mm. While particular embodiments of the present invention have been shown and discribed, it will of course be obvious to one skilled in the art that certain advantages and modifications can be effected without the departing from the spirit of the invention, such as the utilization of more than two cameras to create a stereoscopic effect. Accordingly, it is intended that the scope of the invention not be determined by the foregoing examples, but only by the scope of the appended claims.

Claims: WE CLAIM 1. An apparatus for producing a three-dimensional display comprising: a. means for generating electronic signals which represent the image of a subject as viewed alternately first from one point of origin and then, time displaced, from another point of origin at a rate within a range of 4 to 30 individual viewings per second; and b. means for sequentially displaying the images represented by said electronic signals. 2. An apparatus for producing a three-dimensional illusion of a subject on a vie ing " -surface comprising: a. a first video camera; b. a second video camera; c. an output terminal; d. means for providing to said first video cam¬ era the image of the subject as viewed from one point of origin and for providing to the second video camera the image of the subject as viewed from another point of origin; e. switching means for coupling the output sig- nals one at a time from said first and second video cameras alternately to said output terminal at a rate within a range between 4 and 30 times per second; and f. display means including a view surface for converting said output signals at said output terminal into a visual display on said viewing surface. 3. The apparatus of claim 1 or 2 wherein said points of origin are displaced from one another a distance less than 65 millimeters. 4. The apparatus of claim 1 .or 2 wherein said points of origin are displaced from one another a distance of about 10 to 15 millimeters. 5. The apparatus of claim 1 or 2 wherein said rate is within a range of between 6 and 15 times per second. 6. The apparatus of claim 1 or 2 wherein said rate is about 8 times per second.

Inventors: CATHEY LECONTE, JONES EDWIN R JR, MCLAURIN A PORTER, CATHEY, LECONTE, JONES, EDWIN, R., JR., MCLAURIN, A., PORTER
Applicants: CJM ASSOCIATES
Application year: 1982
Main classification: H04N9