Patent Publication Number: US-7724278-B2

Title: Apparatus with moveable headrest for viewing images from a changing direction-of-view

Description:
RELATED APPLICATION 
     The present application is a continuation of U.S. Ser. No. 09/772,016 filed Jan. 29, 2001 now U.S. Pat. No. 6,798,443 issued Sep. 28, 2004 which is a continuation-in-part of U.S. patent application Ser. No. 08/794,122, filed 3 Feb. 1997 now U.S. Pat. No. 6,181,371 which is itself a continuation-in-part of U.S. patent application Ser. No. 08/452,510, filed 30 May 1995, entitled an “Apparatus For Inducing Attitudinal Head Movements For Passive Virtual Reality,” now U.S. Pat. No. 5,734,421. This application also claims priority from U.S. provisional application 60/124,642 filed Mar. 16, 1999, now U.S. application Ser. No. 09/524,491 filed Mar. 13, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to providing light for forming images and, more particularly, to providing light for forming images for a passive viewer. 
     2. Description of the Prior Art 
     Still photography, motion pictures and television were influenced by the way artists represented physical reality in paintings, as if through a window. A highly detailed perspective image is provided, typically within a rectangular frame. All provide highly detailed images which induce the viewer to cooperate with the cameraman&#39;s “vision” by assuming the artificial perspective of the representation. The viewer is enabled to deliberately suspend disbelief that the images themselves are not a real object space. The degree to which the viewer is thus enabled is influenced not only by the image resolution but by the field of view. It is usually thought desirable to increase both. For example, very high resolution commercial television standards have been formulated for increasing image quality. Such approaches typically increase the number of horizontal lines scanned to a number significantly greater than present standards. Larger format movie film such as 70 mm has been used to increase detail. Also, panoramic movies, e.g., “Cinerama” increased the field of view to increase realism. Various stereoscopic television approaches have also been conceived or developed to increase realism. 
     All of these traditional media take a rather objective view of the physical world. The image is framed by a window through which the viewer can gaze in any direction “into” a representation of an object space. Events are presented in both movies and television in a series of different action scenes in a story line which the viewer can observe from a stable and seemingly quasi-omniscient point of view. The viewer is led to take what appears to be a view of the world as it really is. Yet the choice of image and its perspective is picked by the creator of the image and the viewer actually assumes a passive role. 
     A sensorama simulator was disclosed by Heilig in U.S. Pat. No. 3,050,870. The senses of an individual were stimulated to simulate an actual experience realistically with images, a breeze, odors, binaural sound and even motion. Heilig also disclosed a stereoscopic television in U.S. Pat. No. 2,955,156. This also was passive. 
     “Virtual reality,” in an electronic image context, goes even further in the direction of increased realism but enables the viewer to take a more active role in selecting the image and the perspective. It means allowing a viewer&#39;s natural gestures, i.e., head and body movements, by means of a computer, to control the images surroundings, as if the viewer were seeing and moving about in a real environment of seeing, hearing and touching. Due to the myriad of possible actions of the viewer, a corresponding multiplicity of virtual activities needs to be available for viewer choice. This would represent the ultimate in artificial experience. 
     A user of a “virtual reality” device will typically don a head-mounted display which provides images of a virtual space that are matched to the sensed position and orientation of the head of the user as the user moves his head in space and time (e.g., the x, y, z position of the head and/or the roll, pitch, yaw attitude of the head). For example, a Fakespace BOOM3C is a Binocular Omni-Orientation Monitor that provides visual displays and tracking integrated with a counterbalanced articulated arm for full six-degree of freedom motion (x, y, z, roll, pitch, yaw) and provided by Fakespace, Inc., 241 Polaris Ave., Mountain View Calif. 94043. Another example would be a wireless magnetic motion capture system such as the STAR*TRAK of Polhemus Incorporated of 1 Hercules Drive PO Box 560 Colchester Vt. 05446. It provides six-degree-of-freedom (position and orientation) data from up to 32 sensors capturing data at up to 120 Hz. 
     The images for such devices are created by a computer program with the assistance of pre-stored image information that is retrieved according to the user&#39;s head movements and presented to the user&#39;s eyes. The user&#39;s head may be coupled to the display. The aim is to present panoramic images covering a wide field of view in order to immerse the user in an artificial reality with which he can interact, as if real. The degree of artificiality need not be total and can instead constitute an “augmented reality” with some artificial objects or symbols superimposed or interposed within the real world as viewed with a see-through, head-mounted or head-coupled display. 
     These advances take advantage of converging technological developments in telecommunications including broadband services, projection optics for head mounted and head-coupled displays (including virtual retinal displays), the ever-increasing computational power of image processing computers, specialized sensors such as gloves designed to sense hand and finger movements, exoskeletons, and the like. They can be expected to lead to exciting interactive games and other new forms of interactive experiences within virtual worlds. 
     This new paradigm represents a very great improvement over the present imaging technology. It joins immersion to interactivity to increase the level of experience. It is now being applied to gaming applications and others such as virtual museums, architectural and interior design mockups, facility tours, “aircraft” rides and the like. 
     The new paradigm would likewise seem to hold the potential for an improvement over the old ways of traditional entertainment such as drama, comedy, documentaries, and the like. By joining immersion and interactivity, the user would be enabled to enter a completely new realm of artificial experience. The user would be given a very high degree of freedom, under his own volition, to navigate in the virtual world and to participate in completely new forms of such entertainment, where the user&#39;s own actions influence the sequence of images and audio provided. 
     Traditional entertainment applications, on the other hand, such as drama, comedy, documentaries, and the like, have not yet been explored by these new technologies. This could be because the traditional applications have usually been presented for passive enjoyment by the viewer. Even though immersion would provide a better experience, interactivity would be contrary to these known traditional entertainment applications, such as storytelling, where people like to relax and be passively led through stories and participate vicariously. Another obstacle would seem to be that the level of complexity of the possible alternative scenarios, depending on the user&#39;s actions, would need to be higher in the traditional arts than for the more predictable and mechanistic art of gaming. 
     For all these various kinds of virtual reality applications, the creation of many possible scenarios for viewer selection creates a massive demand for electronic image storage space and there is also the problem of a disconcerting time lag between the viewer&#39;s action and the response of the imaging system. These problems make this emerging technology hard to achieve using presently available hardware. The software task is equally daunting. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a new method and means of providing light for forming images for a viewer. 
     According to the present invention, a method of providing light from a light source at an orientation of the light source to an eye in a head of a viewer for formation of images in the eye, comprises the steps of: 
     providing the light from the light source for the formation of images with a changing point of view; and 
     changing the orientation of the light source in correspondence with the changing point of view for guiding the head of the viewer in a correspondingly changing orientation for viewing the images with the eye in the head of the viewer at the changing orientation of the light source and from the changing point of view. 
     The present invention may be carried out by apparatus, comprising: 
     a light source, responsive to a light control signal, for providing light for viewing images by an eye in a head of a passive viewer; and 
     a light source actuator, responsive to a head guide control signal, for causing the light source to execute attitudinal movements for emulation by the head of the passive viewer. 
     The actuator may be a robot configuration selected from the group consisting of Cartesian, cylindrical, spherical, and articulated robot configurations. 
     The images may but need not be created by means of one or more cameras associated with a cameraman, for example, on the head of a cameraman. These are provided, according to the invention, for passive perception by a viewer whose head movements are guided by a motion-controlled head guide that is actuated in such a way as to emulate head movements of the cameraman in synchronism with the images actively sensed by the cameraman. The “cameraman,” if there is such, can but need not have one or more cameras mounted on his head and the direction of his head with respect to a selected reference frame is monitored; head monitoring signals are stored in association with individual images picked up by the head-mounted camera or cameras. Such images are provided “live” or are played back to the passive viewer by way of a display fixed on or in the head guide, e.g., by way of a headup display fixed to the head guide. The motion of the head guide is controlled with respect to the individual images by retrieving the previously stored head monitoring signals in synchronization therewith. The head of the passive viewer is urged by the controlled movements of the head guide to execute head movements emulative of the monitored motions of the cameraman at the time of image acquisition. 
     Simulated active percepts, according to the present invention, permit a viewer to experience percepts passively, as if inside the head of another person. This “other person” is the “one” controlling the acquisition of the percepts experienced by the passive viewer. Even though the images presented to the passive viewer may be panning about and changing perspective at the whim of the “other person,” e.g., the cameraman, the passive viewer has those images presented to his eyes while his head is also urged to move in the same direction as that of the cameraman&#39;s head so that it is directionally coordinated with the images viewed by the cameraman, as if he were viewing them himself, through his own eyes. 
     It should be realized that cameras are not needed and the images can be created by means of a computer workstation or even by known animation techniques coupled with computers and/or cinematography. In that case, the head movements can be preplanned rather than sensed. 
     There can be a large number of passive viewers with their own motion-controlled head guides. These can be embodied in second-hand (passive) experience simulators, e.g., in the form of self-contained booths each with a multi-degree of freedom head guide for connection within. The viewer&#39;s head guide may be actuated in any number of degrees of freedom, as a matter of design choice, to exert some minimum degree of mechanical head guidance control with just a few actuators or can provide a full complement of actuators, e.g., providing control in six or even more axes. A booth can be for home or arcade use, for example. Such a viewer enters the booth, sits down and mechanically couples his head to the head guide. E.g., the display may be a panoramic display fixed in the wall of the booth or may be a helmet mounted display, as known in the art. The invention need not be embodied in a booth. It can be desk mounted or mounted in any convenient way. 
     The images provided to the passive viewer&#39;s eyes can be varied in their apparent distances, e.g., by changing the focus of the optics in an eyepiece of the light source. In this way, the accommodation of the eyes of the viewer can be urged to follow the changes in focus at differing depths within the image space. 
     The invention may be made even more like a re-experience of experiences of another, according to another aspect of the present invention, by effectively controlling eye movements of the passive viewer in such a way as to emulative of eye movements of the other, e.g., the cameraman. This can be done in a nonintrusive way by presenting nonuniform images emulative of the human fovea, e.g., with nonuniform resolution, nonuniform dynamic range, a small colored area in an otherwise wide-field black and white image, nonuniform image informational content, nonuniform image concentration, nonuniform brightness, or some other equivalent nonuniform images to the passive viewer, made so as to draw the viewer&#39;s attention to an accentuated area, wherein such area moves about between successive images presented within the field of view of the viewer. In this way, not only the head of the passive viewer has its motions guided but the eye movements are guided as well. So the passive viewer can have his head guided to be directed in one direction while the attention of his eyes is drawn or guided in another direction. In this way, the passive viewer feels even more like he is undergoing experiences of another, e.g., the cameraman. Such images can be created by monitoring one or both eyes of the cameraman and causing the image information gathered by the cameras to be encoded in a nonuniform way such as by having finer scanning in a small area dictated by where the cameraman happens to be looking at a given moment with the rest of the field scanned coarsely. 
     Furthermore, when coupled with the previously described changing focus for changing the apparent distances of the images, the foveal viewing aspect of the invention can be used to “control” the exact point of fixation to which the passive viewer&#39;s visual attention is directed, thereby establishing a sequence of fixations at various points at various depths in the image space with correspondingly differing accommodation and convergence of the viewer&#39;s eyes. 
     Such simulated active percepts may be presented “live” or may be stored and retrieved from storage and later presented for passive perception. A booth can, for example, be provided with a video cassette recorder to playback the image and head guide control information. The stored imagery could even be downloaded or provided “live” from the Internet. 
     In the case of stored simulated active percepts, according to the teachings hereof, since there is only one set of images to store, the massive memory demand problem of the prior art of “virtual reality” is solved. Similarly, for the “live” case, since the simulated active percept is provided at the same time as it is created, there is no storage requirement at all, i.e., beyond temporary, “on-the-fly” storage needs. 
     Moreover, by providing simulated active percepts for passive perception, there is no longer any time lag or latency problem as is presently the case for known virtual reality applications. Since the simulated active percepts induce the passive viewer to emulate those physical actions which caused or would have caused the simulated active percepts, the hardware need not be faster or as fast as the viewer. In fact, it may be much slower. Although the viewer is relegated to a passive role, the novelty and richness of the “virtual reality,” immersive experience more than compensates in opening a whole new world of opportunity for representing reality. 
     These and other objects, features and advantages of the present invention will become more apparent in light of a detailed description of a best mode embodiment thereof which follows, as illustrated in the accompanying drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  shows apparatus for providing light to an eye in a head of a viewer for formation of images in the eye, according to a first aspect of the present invention. 
         FIG. 2A  shows a suspended embodiment of the apparatus of  FIG. 1 . 
         FIG. 2B  shows a desktop supported embodiment of the apparatus of  FIG. 1 . 
         FIG. 3  shows various robot embodiments of the apparatus of  FIG. 1 . 
         FIG. 4  shows one of the robot configurations of  FIG. 3  in more detail. 
         FIG. 5 , according to a second aspect of the invention, shows a cameraman in an image space for gathering light in cameras for transformation into the light control signal of  FIG. 1 . 
         FIG. 6  illustrates various ways, according to a second aspect of the present invention, to create the light control signal and the head guide control signal of  FIG. 1 . 
         FIG. 7 , according to an embodiment of the second aspect of the present invention, shows a helmet for a cameraman in an object space having at least one camera and various sensors for at least monitoring head attitude and a signal processor or encoder for providing an encoded signal to a decoder, according to the first aspect of the invention, in an image space where decoded signals are provided to a helmet attitude control and to a display control for providing actuator control signals to at least a helmet attitude actuator mounted in a frame such as an arcade booth and to a helmet mounted display. 
         FIG. 8  shows one of the three attitude sensing planes of  FIG. 7  for sensing pitch attitude of the cameraman&#39;s head, according to the invention. 
         FIG. 9  shows a series of steps which may be carried out by the encoder of  FIG. 7  prior to encoding the pitch control information for subsequent use in the image space, according to the invention. 
         FIG. 10  shows a series of steps that may be carried out in the encoder in the object space for encoding the video, head attitude and eye direction data, according to the invention. 
         FIG. 11  shows a series of steps that may be carried out in the decoder in the image space, according to the invention. 
         FIG. 12  shows more details of the relation between the sensors and encoder in the object space of  FIG. 7 , according to the invention. 
         FIG. 13  illustrates aspects of the sensors and encoder of the object space as well as the decoder and controls of the image space in more detail, according to the invention. 
         FIG. 14  shows in an expanded view the details of the motion-controlled helmet of the image space of  FIG. 7 , according to the present invention. 
         FIG. 15  shows a perspective view of a universal-joint such as may be fixedly mounted within the joint  106  of  FIG. 14 . 
         FIG. 16  shows in plan view the U-joint of  FIG. 15  within the gear of  FIG. 14 . 
         FIG. 17  shows a coordinate system appropriate for the motion-controlled helmet of  FIGS. 7 and 14  by means of which the sensed signals in the object space of  FIGS. 7 ,  12 , and  13  can be transformed into attitudinal movements of the viewer&#39;s head. 
         FIG. 18  shows a series of monocular images gathered by a cameraman in an object space for presentation to a passive viewer as nonuniform images, according to the invention. 
         FIG. 19  shows a series of stereo images similar to those of  FIG. 18 , according to the invention. 
         FIG. 20  shows a pair of eyes fixating at different points. 
         FIG. 21  shows a series of stereo image pairs similar to those of  FIGS. 18 and 19  that achieves high resolution binocular viewing, except without a need for eye tracking in the object space, according to the invention. 
         FIG. 22  shows a moveable headrest for supporting the head of a user in executing head movements while viewing images from a changing direction, according to the invention. 
         FIG. 23  shows a user reclining on a support in the form of a recliner equipped with a moveable headrest while viewing images from a changing direction, according tot he invention. 
         FIG. 24  shows a user standing on a support in the form of a human activity simulator equipped with a moveable headrest while viewing images from a changing direction, according to the invention. 
         FIG. 25  shows a user seated on a support in the form of a chair equipped with a moveable headrest while viewing images from a changing direction, according tot he invention. 
         FIG. 26  shows a moveable headrest with a pivotal support assembly for supporting the head of a user in executing head movements while viewing images from a changing direction. 
         FIG. 27  shows the head of the user of  FIG. 26  from above as the user views a scene with a straight-ahead direction-of-view. 
         FIG. 28  shows the head of the user of  FIG. 26  from above as the user views a scene with a leftward direction-of-view. 
         FIG. 29  shows the head of the user of  FIG. 26  from above as the user views a scene with a rightward direction-of-view. 
         FIG. 30  shows an open-loop proportional control for a moveable headrest used passively. 
         FIG. 31  shows a closed loop proportional-plus-integral control for a moveable headrest used passively. 
         FIG. 32  shows hardware setup for active use of the moveable headrest, i.e., with the user moving his head at will. 
         FIG. 33  is the same as  FIG. 32  except that the reality engine  70   b  is remote and is accessed via a network  74   b.    
         FIG. 34  shows passive use of the moveable headrest with an actuator  14   c  moving the headrest and hence the user&#39;s head in response to a signal on a line  16   c  from a local reality engine  70   c.    
         FIG. 35  is the same as  FIG. 34  except the reality engine is remote. 
         FIG. 36  shows a video camera collecting images of a scene illuminated by a light source with an eye of a cameraman shown using an eyepiece to view the scene being photographed. 
         FIG. 37  shows apparatus for showing images to an eye of a user with appropriate granularity. 
         FIG. 38  shows light rays projected to form an image that fills or almost fills the entire area or extent of a screen shown in  FIG. 37 . 
         FIG. 39  shows light rays projected to form an image that only partially fills the entire extent of the screen of  FIG. 37 . 
         FIG. 40  shows light rays projected to form an image that only fills a small extent of the entire extent of the screen of  FIG. 37 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows an apparatus  10 , according to the present invention, for providing light  12  to an eye  14  in a head  16  of a passive viewer for formation of images in the eye  14 . The apparatus  10  comprises a light source  18 , responsive to a light control signal on a line  20 , for providing the light  12  for the formation of the images with a changing point of view. The light source  18  may be any kind of device for providing light which is cast on the retina to form an image. In other words, it should be realized that the light source  18  could be any type of light source, including but not limited to the many various known types of displays. Such displays may include those where an image is first formed outside the eye, including but not limited to any type of head mounted display (HMD) or, e.g., any type of display where the image is first formed inside the eye including any type of virtual retinal display (VRD). See U.S. Pat. Nos. 5,184,231; 5,189,512; 5,406,415; 5,293,271; 4,969,714; 4,968,123; and 4,961,626 for typical examples of HMDs. See U.S. Pat. Nos. 5,467,104, 5,596,339 and 5,574,473 for examples of VRDs. 
     A head guide  22  is connected to the light source  18  and is responsive to a head guide control signal on a line  24 , for mechanically changing the orientation of the light source  18  in correspondence with the changing point of view for guiding the head  16  of the viewer in a correspondingly changing orientation for viewing the images with the eye  14  in the head  16  of the viewer at the changing orientation of the light source  18  and from the changing point of view. “Changing orientation” is used in the same sense as one or more of the pitch, roll, or yaw components of changing attitudes for aircraft or spacecraft. The head guide is thus a light source actuator or mover of the light source in order to be a guider of corresponding movements of the head of the viewer. 
     A mechanical head coupler  26  for coupling the head  16  of the viewer to the light source  18 , or even to the head guide  22  as indicated by a line  26   a  may, but need not, be provided as well for assisting in guiding the head of the viewer in changing its orientation in following the changing orientations of the light source. In other words, the function of the head coupler  26  is to provide a way to couple the head or face of the viewer to the display so as to facilitate guidance of the head of the viewer  16  in passively following movements of the light source  18  as controlled by the head guide  22 . Such a head coupler  26  can take the form of a hollow casing, a portion being concave to fit about the face of the head of the viewer  16 , said portion have two eye openings to be looked through by the viewer&#39;s eyes as shown, e.g., by M. L. Heilig in U.S. Pat. No. 2,955,156 or 3,050,870 or as similarly shown, more recently, in a wrap-around viewer by the Nintendo “Virtual Boy” (Part # 32787 Item # NESM128). It could simply be eyecups which the viewer inserts his eyes into and rests his brows, cheeks or eye-orbits against. It could be a head or face “rest” that is rigidly attached to the light source as shown in FIG. 3 of U.S. Pat. No. 5,584,696 where the viewer looks through a single aperture. It could be a helmet or headrest. In other words, it can be any means for more or less weakly or strongly mechanically coupling the head of the viewer to facilitate the function of the head guide in mechanically guiding the head of the viewer to follow the movements of the light source. 
     With the passive viewer seated or standing before the light source, the head  16  of the viewer is coupled to the light source  18  by the means for coupling  26 . The light source provides light  12  to the eye for forming an image in the eye from a particular point of view as controlled by the light control signal on the line  20 . As long as the point of view remains the same, the head guide  22  does not change the orientation of the light source and the scene remains the same. However, the light control signal can then gradually or even quickly change the point of view and the head guide will at the same time correspondingly change the orientation of the light source according to the dictates of the head guide control signal. The head of the viewer is thus guided in such a way as to feel the changing orientation of the point of view as if experiencing the change in reality. 
     For a simple case such as shown for example in  FIG. 2A , the means for changing the orientation of the light source (in the form of a display housing  18   a ) may be supported on a fixed support  28  on a base  29  so that the position of the display housing, to which it is connected, e.g., by means of a one-or-more axis wrist, e.g., a three-axis wrist  22   a , is also essentially fixed, ie., with respect to translations in position. The base shown is a ceiling or roof base but could as well be reversed as a floor base. As shown in  FIG. 2B , the base could be any surface such as a desk  29   a  with a support  28   a ,  28   b  holding the display much like a desktop computer except with a wrist  22   b . Both of the wrists of  FIGS. 2A &amp; 2B  have an actuator such as a motor in one or more axes for causing movement thereabout. The motor can be of any type including electrical, hydraulic, or the like. The display housings  18   a ,  18   b  are shown with the head coupler in the form of simple eyecups  26   a ,  26   b  such as found on binoculars. Behind each eyecup may be a separate light source such as shown, e.g., in U.S. Pat. No. 4,406,532. Other kinds of displays without separate eyecups are equally usable. Handgrips  30  may be provided as part of such means to assist the viewer in coupling his or her head to the eyecups. This embodiment is somewhat similar to a submarine periscope except that such a periscope has a telescoping support for changing the vertical position of the scope and only has a single degree of freedom of orientation, i.e., for changing the orientation of the scope about the axis of the support. 
     On the other hand, the head guide  22  of  FIG. 1  may, in addition to being capable of changing the orientation of the light source, be equipped to change the translatory position of the light source. As shown in  FIG. 3 , the means for changing the orientation of a light source  18   c , e.g. in the form of a motorized wrist  22   c , can be mounted on a means  32  for changing not only the orientation but the position of the display as well. Such a means  32  can take the form of a selected robot configuration as shown, for example, in  FIG. 3 . Such a robot has a work envelope having a shape depending on the selected configuration. Various configurations are shown at pages 2154-62 of  The Electrical Engineering Handbook , CRC Press 1993, edited by Richard C. Dorf, in section 94.1 entitled “Robot Configuration” at pages 2154-62 by Ty A. Lasky, Tien C. Hsia, R. Lal Tummala, and Nicholas G. Odrey, e.g., “cartesian” as described and shown at pages 2155-6, “cylindrical” as shown at page 2156, “spherical” as shown at pages 2157, “articulated” as shown at pages 2157-8, “SCARA” as shown at pages 2158-9, and “gantry” as shown at pages 2159-61. As explained there, “configuration” refers to the way the manipulator links are connected at each joint. Each link will be connected to the subsequent link by either a linear (sliding or prismatic) joint, or a revolute (or rotary) joint. 
     For example, as shown in  FIG. 4 , the means for changing the orientation of a light source  18   d , e.g., in the form of a wrist  22   d , can be mounted by a rigid bar  33  onto a cylindrical robot configuration  32   c  for changing the position of the display. It has one vertical revolute joint  34  and two orthogonal linear joints  36 ,  38 . Such a cylindrical robot has a work envelope in the form of an annulus or part thereof as illustrated in FIG. 94.4 at page 2157 of  The Electrical Engineering Handbook , referred to above. Cylindrical robots are made by many different manufacturers, e.g., the RT3200 or RT 3300 of Seiko Instruments USA, Inc., 2990 W. Lomita Blvd., Torrance, Calif. 90505. 
     There are many possible alternatives for creating the light control signal on the line  20  and the head guide control signal on the line  24  of  FIG. 1 . For example,  FIG. 5  shows a studio cameraman  40  having headgear with stereo cameras  44 ,  46  attached thereto for providing the light control signal on the line  20  of  FIG. 1 . The cameras can be of high definition, e.g., according to the new HDTV standard recently promulgated by the FCC or can instead be any other type for providing a wide field of view image. See, for example, U.S. Pat. No. 4,323,925 for an image sensor suitable for resolving a high-resolution image. The cameras can instead be mounted on rails  48 ,  50  of a structure  52  or in any other convenient location that permits the cameras to be mounted so as to be pointing in the same direction as the cameraman&#39;s head and so as to gather images of a scene from the moving point of view of the cameraman. The structure  52  is in turn connected to a counterbalanced articulated arm  54  such as heretofore used for a different purpose in the BOOM3C of Fakespace Inc., 241 Polaris Ave., Mountain View, Calif. 94043. For example, it can have a first arm  56  connected at one end to the structure  52  by joints  58 ,  60  and at the other end to a counterweight  62 . A joint  64  connects the first arm  56  to a second arm  62  which is in turn connected to a pedestal  64  by additional joints  66 ,  68 . The joints need not be located at the exact same positions shown but can be changed, if a different design is desired. Each of the joints has a transducer associated therewith for monitoring rotation about the axis of the associated joint. Signal processing of signals from the transducers provides an indication of position and orientation of the cameraman&#39;s head in space. Thus, the structure  52  is used for providing full six-degree of freedom motion monitoring for providing the mover control signal on the line  24  of  FIG. 1 . The articulated arm  54  is mounted on a pedestal  56  which may be stationary or movable on a studio dolly. For the embodiment shown, the cameraman can move his head in different orientations and positions. He can walk about within the confines of the work envelope of the articulated arm and thus provide the light control signal  20  of  FIG. 1  for use by the light source in providing light at a point of view that changes with movements of the cameraman&#39;s head. It should be realized that there are numerous other similar mechanical monitors available. See, e.g., U.S. Pat. No. 4,586,515 for a device for measuring the position and/or motion of a body part. 
     As mentioned above, it should be realized that there are alternative ways to create the light control signal on the line  20  as well as the mover control signal on the line  24 .  FIG. 6  shows a generalized means  70  for indicting head attitude, as well as head position if desired. The means  70  can take the form of a mechanical head-coupled tracker  72  such as shown in  FIG. 5  for providing a mover control signal on a line  24   a . An OR gate  74  is shown in the means  70  of  FIG. 6  merely to indicate hat there are alternatives to the arrangement of  FIG. 5  for providing a mover control signal on a line  24   c  to a signal storage medium  76 . Such an OR gate  74  would not actually be present since only one alternative is needed. It is shown for the purpose of indicating that there are various alternatives. Another way for indicating head position and attitude is to use a head mounted navigation system  78  for sensing position and attitude with gyros, accelerometers, radio; magnetic sensors, or the like for providing a mover control signal on a line  24   b . such a system is shown in the object space of  FIG. 7  below. Another approach would be a system from Polhemus Inc., such as the system mentioned above. Yet another approach is shown by a block  80  in  FIG. 6  which represents a way for a designer to provide a head guide control signal on a line  24   d . This could be done by a computer workstation. 
       FIG. 6  also shows a means  82  for providing a light control signal  20   a  to the storage medium  76 . It can comprise cameras such as head coupled cameras  84  for providing a light control signal on a line  20   b  such as shown in  FIG. 5  and in  FIG. 7  below or it can comprise a means  86  such as a computer workstation for providing a light control signal on as line  20   c . The two alternative signals on the lines  20   b ,  20   c  are shown provided to a fictitious OR gate  88  to signify that either alternative  84 ,  86  can be used. The OR gate  88  of course need not be actually and would not usually be present. This is not to say, however, that post-production work could not be done on camera generated imagery by means of a workstation. 
     The signal storage medium  76  is responsive to the head guide control signal on the line  24   c  and the light control signal on the line  20   a  for storing them in timed relation to each other in such a way that they can later be retrieved in the same timed relation and provided on lines  20   d ,  20   e  as a combined output signal for use by a light source such as shown in  FIG. 1 . It should be understood that although the various signals on the lines  20 ,  24  may be shown as single lines that they can each typically comprise a plurality of signal lines. 
       FIG. 7  shows in an object space  100  one of the particular means  78  for the means  70  as well as one of the particular means  84  for the means  82  of  FIG. 6 . It should be realized, however, that the various particular means of the means  70  of  FIG. 6  can be used in various combinations with the various particular means of the means  82  of  FIG. 6 . 
       FIG. 7  shows both the object space  100  and an image space  102 , each of which may have respective helmets  103 ,  104  therein, or their equivalents, according to the present invention. The image space is for presentation of images to a “viewer” while the object space is for image acquisition, e.g., by an “observer.” The linguistic convention of calling the active creator of the image the “observer” in the “object” space and the passive consumer of the created image in the “image” space as the “viewer” will be used throughout. 
     According to the present invention, the helmet  104  in the image space  102  is worn by a passive viewer (not shown), e.g., seated within a stationary arcade-like housing (not shown) with respect to which the helmet  104  is made to move. It is made to execute at least some minimum movement such as one or more attitudinal movements emulative of pitch, roll and yaw movements of the helmet  103  in the object space  100  and worn by a cameraman observer (not shown) who is free to move about while directing his head and gaze in various directions. In other words, translatory movements of the head of the observer with respect to some referent may, but need not be, emulated by the helmet of the viewer. For the detailed embodiment shown below, however, only the attitude of the cameraman&#39;s head is emulated in the image space. Translations are ignored. This makes it possible for the embodiment shown for the viewer&#39;s head to remain relatively stationary (not be forced to undergo various translatory accelerations) in the image space in a positional sense. Such can be introduced but are best imparted to the body of the viewer rather than directly to the head. Such requires additional sets of external platforms and associated superstructures depending on the number of axes of control and are shown below in other embodiments. For the case shown where only head attitude is emulated, the viewer can be seated or standing in one position within a stationary structure. 
     It will be realized, therefore, that the invention can be used in platforms in which the viewer can be controlled in other ways. For instance, the viewer could be seated as shown in FIG. 1 of U.S. Pat. No. 5,515,078 with the display FIG. 1 of that patent controlled in the manner disclosed herein. The display  21  of that patent could be positioned as shown therein or more closely, with its arm  11  angled to bring the display  21  close to the face of the user to facilitate use of a head coupler as taught herein. In addition to controlling the orientation of the display  21  as taught herein, however, the position and/or orientation of the seated viewer can be controlled as shown in FIG. 3 of U.S. Pat. No. 5,515,078 except not based on the joystick  30 ,  35  choices of the viewer, but passively, based on monitoring of the position and/or orientation of the cameraman in the object space based on the same principles as disclosed herein. The invention can similarly be used with like devices such as shown in U.S. Pat. Nos. 5,388,991; 5,551,920; 5,453,011; and 5,353,242, among many others. 
     At the same time, a helmet mounted display  106 , to be described below, mounted on the helmet  104 , provides images to the passive viewer wearing the helmet  104  that are gathered by the cameraman “observer” in the object space  100  wearing the helmet  103  with cameras mounted thereon. The images viewed by the passive viewer in the image space are therefore presented in such a way as to be emulative of images seen by the cameraman as he moves his head, at least attitudinally, in the object space. It should be realized that translational position of the observer&#39;s head can be monitored in the object space as well, with respect to a selected referent, and such translations can be emulated by the helmet  104  in the image space by means of the already mentioned additional platforms and associated superstructures (not shown). Or, rather than urging the head of the viewer to translate directly, such positional translations can instead be imparted to a platform supporting the body of the viewer, as shown below in other embodiments. It should be mentioned that the body of the cameraman can be monitored as well or instead of the head, at least for purposes of translation. 
     The helmet  103  in the object space  100  has at least one camera  108 , and preferably a second camera  110  as well, mounted on opposite sides of the helmet  103  for respectively gathering monocular or preferably stereoscopic images of objects in the object space according to the cameraman&#39;s head movements. The cameras provide image signals on lines  112 ,  114  to a signal processor or encoder  116  where they are encoded for transmission to the image space  102  via a signal on a line  118 . 
     Also illustrated mounted on the helmet  103  are helmet attitude sensors  120 ,  122 ,  124  such as, but not limited to, accelerometers for monitoring the cameraman&#39;s head attitude, respectively, its pitch (P), roll (R) and yaw (Y). Opposite on the helmet to each of the illustrated sensors  120 ,  122 ,  124  may be located corresponding sensors  126 ,  128 ,  129  (not shown in  FIG. 1 ) as twins to sensors  120 ,  122 ,  124  for sensing equidistantly on opposite side of the helmet. For example, as shown in  FIG. 8 , the pitch (P) sensor  120  on the front of the helmet  103 , e.g., just above the visor, may have a corresponding twin pitch sensor  126  (not shown in  FIG. 7 ) on the back of the helmet opposite to the sensor  120 . These two sensors are shown in  FIG. 8  located on positive and negative equally spaced sides of a y-axis in a y-z plane of a three-axis (x,y,z) coordinate system (having three such mutually orthogonal planes) having an origin centered on the head of the observer at a point  130 . Such a three axis system is illustrated with the origin  130  translated to a point  130   a  for purposes of clarity, above the helmet  103  of  FIG. 7  but it should be understood that it is most convenient to position the origin of the illustrated coordinate system at the point  130  at the center of the cameraman&#39;s head, as shown. Of course, the origin can be located at any convenient point and translated as desired by appropriate coordinate translations and transformations. 
     In any event, the two sensed pitch signals from the accelerometers  120 ,  126  of  FIG. 8  may be used together to be indicative of pitch (P) rotations in the y-z plane about the point  130  midway between them, e.g., in the center of the cameraman&#39;s head. It should be realized, however, that a single sensor can suffice. Similarly, twin roll and yaw sensors may be positioned at equal distances apart (in corresponding mutually orthogonal roll and yaw sensing planes) on opposite sides of the helmet for sensing roll and yaw motions about substantially the same center point  130 . For example, as shown in the object space of  FIG. 7 , the roll acceleration sensor  122  may be positioned as shown on the helmet over left ear of the observer and oriented as shown on a positive side of the x-axis while a not shown acceleration sensor  128  may be similarly positioned over the right ear of the observer on the other side of the helmet on a negative side of the x-axis. Together, they may be used inter alia to measure rotations in the x-z axis about the point  130  in the center of the cameraman&#39;s head. Similarly, the acceleration sensor  124  of  FIG. 7  may be positioned over the left ear of the observer and oriented as shown in  FIG. 7  on the positive x-axis with a not shown acceleration sensor  129  similarly positioned over the right ear of the observer on the other side of the helmet on the negative x-axis. Together, they may be used inter alia to measure rotations in the x-y axis about the point  130 . It should be realized that it is also possible to monitor the attitude of the cameraman&#39;s head with any appropriate sensor with respect to another referent, such as but not limited to his body. 
     The sensors need not be accelerometers but could be gyros of the electromechanical type, SAGNAC effect fiber optic gyros, or conceivably even more bulky laser gyros. Other types of attitude sensors based on magnetic sensors, light beam sensors, radio sensors, or the like, are known and are of course useable as well, as will be understood by those of skill in the art. 
     It should be realized that although  FIG. 7  shows the image creation process as taking place in an “object” space  100  by means of a camera on a helmet gathering images of real objects and mounted on a helmet, similar images can be created in other ways, e.g., by animation or successive images created on computers, using software, as suggested above in connection with the block  80  of  FIG. 6 . 
     In any event, as shown in  FIG. 7 , the sensed attitude signals may altogether be provided on an illustrative line  131  to the signal processor or encoder  116  for being encoded along with the image signals on the lines  112 ,  114 . They may be combined, for example, using time division multiplexing techniques or by any other convenient technique. Or the signal processor or encoder can calculate the attitude of the cameraman&#39;s head based on the sensed signals in the object space and encode appropriate actuator signals for transmission to the image space. It should be realized, however, that the helmet attitude and image signals need not be processed and combined into a single signal on the line  118 , but may be processed and provided separately. Each of the acceleration signals may be separately processed in the signal processor or encoder  116  to provide an indication of angular displacement in each of the separate pitch, roll and yaw axes. For example, the pitch axis may, but need not, be defined in the y-z plane shown by the x-y-z axes of  FIG. 7  centered at the point  130  in the object space of  FIG. 7 . Similarly, the yaw axis may, but need not, be defined in the x-y plane and the roll axis in the x-z plane. 
       FIG. 9  shows a signal processing method which may be used for evaluating the sensed acceleration signals to determine the cameraman&#39;s head attitude in the y-z (pitch) plane of  FIGS. 7 &amp; 88 . Though not shown, a similar signal processing method may be used for evaluating the sensed acceleration signals in the x-z (roll) and x-y (yaw) planes. At the outset, it should be realized that other equally effective coordinate systems (such as polar or cylindrical coordinate systems) and methods may be used and the following is just one example. 
     According to  FIG. 9 , after entering in a step  131   a , a pair of initialization steps  132 ,  134  are executed to set a rotation variable RTN(R) and a translation variable XLTN(T) equal to zero at a selected cameraman reference attitude and position, e.g., standing erect and head pointing straight-ahead with respect to a selected axis. For this example, the variable XLTN(T) represents the position of the point  130  with respect to the z axis of  FIG. 7  or  8 . 
     After initialization, a decision step  136  is executed to determine if acceleration (A) has been sensed by the accelerometers  120 ,  126  of  FIG. 8 . If not, then the step  136  is re-executed until such is sensed. Due to their bidirectionality and orientation in the z direction, both sensors will sense an acceleration along the z axis whether it be positive or negative. Once acceleration is sensed, a step  138  is executed to determine if a rotational acceleration is sensed by the accelerometers or not. I.e., if the accelerometers sense translations in opposite directions at the same time, this is interpreted as sensing a rotation. 
     If a rotation has been sensed, a decision step  140  is executed to determine if the sensed rotation is a pure rotation in the y-z plane about the point  130  or if it is accompanied by a translation of the point  130  in the z direction. It can do this by comparing the absolute magnitudes of the oppositely sensed accelerations of the two sensors  120 ,  126 . If they are equal, then they represent a pure rotation. If not, then there is also a translation present in the positive or negative direction. 
     In the case where they are not equal, a step  142  may be executed to determine the magnitude of the equal and opposite sensed accelerations that are together indicative of the magnitude of the arc of rotation and its direction. The equal but opposite accelerations will either both indicate a clockwise rotation or a counterclockwise rotation. For instance, if sensor  120  indicates an acceleration in the positive z direction and sensor  126  indicates an acceleration in the negative z direction then the rotation is in the clockwise direction. 
     If knowledge of translations is desired, the step  142  can be executed to determine the magnitudes of the two oppositely sensed accelerations and then, in a step  144 , to determine the part of one of the sensed accelerations that exceeds the other, i.e., to determine the difference (ΔA) between the sensed accelerations. The difference can then be integrated twice to determine the length of the translation and summed with the previous value of XL TN(T), as indicated in a step  146 , to indicate the current z position. Such knowledge may be needed for instance in all three orthogonal planes, not just the y-z plane, where it is desired to keep track of the three dimensional translatory position of the head of the cameraman. Such is not used in the present application but it could be used in other applications. 
     In a step  148 , executed subsequent to either the translation update step  146  or the decision step  140 , the sensed acceleration (A) (i.e., the acceleration that is equal in terms of absolute value in both sensors) is twice integrated to determine the length of arc of rotation of the movement of the cameraman&#39;s head about the point  130 . The doubly integrated acceleration is summed in a step  150  with the previous value of the pitch rotation value RTN(R). Since the radius (r) from the point  130  to each of the accelerometers is known and since the arc of rotation is known from the foregoing, the angle of rotation in the y-z plane can be determined. I.e., if the radius (r) of a circle is known, the length of an arc (a=RTN(R)) on the circumference can be used to measure the corresponding angle (P) at the center. Consequently, the pitch angle (P) can be determined in degrees as shown in a step  152  according to the relation 2πr/RTN(R)=360/P. At this point, as described in more detail below, calculation of the necessary movement of the platform  153  of  FIG. 14  in the y direction can be made and output for encoding with the video signal as indicated in steps  154 ,  156 . 
     The step  136  is then re-executed to determine if additional accelerations have been sensed. Once again, if no additional accelerations have been sensed then the step  136  is executed again ad infinitum until an acceleration is sensed. At that time, the decision step  138  is executed to determine if there has been a rotation. 
     If it is important to determine translations in the y-z plane, a step  158  may be executed after the step  138  to determine the magnitude and direction of the acceleration (A) from the sensors  120 ,  126 . The step  160  is next executed in order to twice integrate the sensed acceleration (A). This determines a pure translation which is added in a step  162  to the previous value of the translation variable XLTN(T). A return is then made to the step  136  to determine if additional accelerations have been sensed. Once again, if no additional accelerations have been sensed then the step  136  is executed again ad infinitum until an acceleration is sensed. At that time, the decision step  138  is executed to determine if there has been a rotation. 
     As mentioned, a similar signal processing method as shown in  FIG. 9  may be executed at the same time (serially or in parallel) for evaluating the sensed acceleration signals in the x-z (roll) and x-y (yaw) planes. These various signal processing procedures may be carried out as shown in  FIG. 9  by means of the signal processor or encoder  116  of  FIG. 7  shown in detail in  FIG. 12 . As also mentioned, for the embodiment shown, translations need not be tracked. Here, it is desired to “divorce” attitudinal motions of the cameraman&#39;s head from translations thereof because of the stationary nature of a structure  164  with respect to which the body of the viewer in the image space  102  is also relatively stationary. In other words, for the preferred embodiment, it is not desired to positively translate the head or body of the viewer in the image space. So, for the illustrated embodiment, the steps  144 ,  146 ,  158 ,  160 ,  162  may be omitted. I.e., if the answer to the question posed in the decision step  138  is negative, then the step  136  may be re-executed directly and steps  1158 ,  160 ,  162  may be omitted completely from the procedure. 
       FIG. 12  shows the signal processor or encoder  116  of  FIG. 7  as a general purpose signal processor capable of carrying out the steps of  FIG. 9 . It may include an input/output (I/O) device  168  which may be represent din part by a device  168   a  for interfacing with an attitude monitor  170  which may, but need not, include the accelerometers  120 ,  122 ,  124 ,  126 ,  128 ,  129 , a left eye monitor  169   a , and a right eye monitor  169   b . These may be any kind of eye monitor such as for monitoring accommodation, position, direction, or the like. It may also include various data, address and control busses  172  for interfacing with a central processing unit (CPU)  174 , one or more memory devices which may include a read-only-memory  176  and a random access memory (RAM)  178 . The I/O device  168  may also be represented in part by a device  168   b  for interfacing with the image space  102  over the line  118 . 
     The left and right eye monitors  169   a ,  169   b  of  FIG. 12  may take the form of a pair of left and right oculometers  180   a ,  180   b . Such a pair of oculometers are capable of monitoring the eyes&#39; attitudes or directions (sometimes called “positions”) and providing a monitored signal such as shown on a line  133  which represents signals indicative thereof. An oculometer device  180  of the illustrated eye direction sensor, for one or both eyes, can for example take the form of an infrared source for illuminating the cameraman&#39;s eye which reflects the infrared light into a directionally sensitive infrared sensor inside the helmet (not shown) for sensing the direction of eye movement. Such is shown for example in U.S. Pat. No. 4,034,401, among many others. It should also be realized that other types of eye monitoring methods may be used as well, and further that it is not necessary to monitor eye attitude at all. Eye attitude is chiefly useful, according to the present invention, for providing a control signal for controlling an area of image nonuniformity such as an area of high resolution, dynamic range, brightness, or the like, in the images displayed to the passive viewer. It many not be necessary in some applications to have such a control signal (and consequently no eye monitoring) since uniform images can certainly be used. Equally, it should be realized that eye attitude, if monitored, can be monitored in any number of axes of eye attitude, including not only pitch and yaw but roll, i.e., torsion (rotation about the visual axis), and could even include, beyond attitude, position monitoring (in the strict sense of the word, i.e., small translations of the eyeball within its socket), although torsion and position monitoring are currently deemed not necessary for a preferred embodiment. 
     All of the various sensed signals in the object space  100  may be represented as a generalized group of sensed signals on the bundle of lines  132  (see  FIGS. 7 &amp; 12 ) for being encoded in a convenient format in the signal processor or encoder  116  for being provided on the line  118  to the image space  102 . Encoding can take place in the encoder  116 , for example, as shown in  FIGS. 10 &amp; 12 . After entering in a step  184 , a block of a selected size of video data from the cameras is input and stored in a step  186 . A step  188  is next executed to input and store eye direction data from the oculometer sensors  180   a ,  180   b . Head attitude data is next input as indicated in a step  190 . Once the sensed head attitude, eye direction and video data is input and stored, a step  192  is then executed in order to retrieve the eye direction data stored in the step  188 . Similarly, at least a part of the video data previously stored in the step  186  is retrieved in a step  194 . The retrieved video data is then encoded in a step  196  according to the retrieved eye direction data. That is, if the eye direction signal indicates that the video data to be encoded is in a portion of the overall image that is to be encoded with a higher or lesser degree of resolution, then the encoding is carried out accordingly. A decision step  198  is then executed to determine if the encoding of the video block is done. If not, the steps  192 ,  194 ,  196  are again executed until the block is encoded. 
     It should be realized that the eye attitude signal can instead be used to directly control the attitude of a 3-axis platform mounted e.g. on the helmet (or elsewhere) and having a camera with a nonuniform lens (e.g., U.S. Pat. No. 3,953,111) mounted thereon which is thereby directed in the same direction as the cameraman&#39;s eye. In that case, the optics of the camera effects the desired nonuniform imagery and nonuniform encoding techniques are not needed. Similar 3-axis camera mounts could be used for the cameras of  FIG. 5 . 
     Head attitude data stored previously in the step  190  is next retrieved as indicated in a step  200 . The head attitude data is then encoded with at least part of the selected video block as indicated in a step  202 . A decision step  204  then determines if the encoding is done. If not, the steps  200 ,  202  are repeated until it is determined in the step  204  that the block is encoded. If a variable focal length device such as a device  205  of  FIG. 7  is used, a step  206  is executed to retrieve the eye data input and stored in step  188 . This may be eye direction or similar data. A step  208  is next executed to determine the distance from the monitored eyes to the point of fixation converged upon by the monitored eyes. This information is then encoded in the selected block of data as indicated in a step  210 . After that, as indicated in a step  212 , the encoded block is stored or transmitted directly to the image space and the step  186  et seq. is executed again. 
     It should be understood that numerous alternative encoding techniques could be carried out as well including analog techniques using dedicated analog circuitry. Anyone of skill in the art could devise a signal encoding technique for transmitting both the video and control information required in the image space based on the teachings hereof. For instance, the video image may be encoded in the conventional analog manner with odd and even raster fields which are interlaced to form a single frame. In that case, several of the horizontal video lines at the top or bottom of a field can be used for encoding the changing pitch, roll and yaw control information. For a given horizontal line used for a control purpose, a selected fixed voltage level between “white” and “black” levels will indicate the delta x, delta y or yaw rotation described in  FIGS. 14-16  and  17  below. Such a control concept is shown for example in FIGS. 2-3 of U.S. Pat. No. 4,513,317 albeit for a different purpose. It should be realized that the encoding technique is not restricted to conventional digital techniques but could take other forms such as, but not limited to, a new HDTV format. Other as yet undefined formats such as for virtual retinal displays may also be used. It should also be realized that the signal on the line  118  need not be provided directly to the image space  102  but can instead be stored on a mechanical, magnetic, optical, electronic, or the like storage medium  214  for subsequent transfer as indicated on a line  216  for playback on a playback device  218  in the image space. The bundle  132  can take the form of a wire harness connected to the encoder  116  which may be carried by the cameraman in a backpack, for example, along with the storage device  214 . 
     A signal processor or decoder  220  in the image space  102  of  FIGS. 7 &amp; 13  is responsive to the encoded signal on the line  118  either directly (live) from the object space or prerecorded and played back on the playback device  218  and provided on a line  219 . The decoder provides decoded image signals on a line  222  to a display control  224  which provides a signal on a line  226  for controlling the display  106  which may be mounted on the helmet  104  which may be monoscopic or stereoscopic, as described previously. The decoder  220  also provides a decoded helmet attitude signal on a line  226  to a helmet attitude control  228  which in turn provides a helmet attitude control signal on a line  230  to a plurality of actuators such as three actuators  232   a ,  232   b ,  232   c  mounted on a stationary plate  234  for actuating the helmet  104  in a corresponding plurality of axes such as three axes, as shown, emulative of the motions of the helmet  103  in the pitch, roll and yaw axes sensed in the object space  100 . The attitude control  228  may, e.g., be a simple open loop having proportional plus integral gain. Although not shown, sensors could be provided on the platform  234  to sense position of the plate, for example, for providing feedback signals fro a closed loop control. In any event, the control  228  provides actuator command signals on the line  230  for causing the actuators to carry out the control strategy described in connection with  FIG. 17  below. 
     The decoder  220  may also provide a variable magnification control signal on a line  236  to the variable magnification device control  205  which in turn provides a variable magnification device control signal on a line  238  to a variable magnification device  239  (see  FIG. 13 ) associated with the display  106  and as disclosed in more detail in copending applications having Ser. Nos. 08/025,975 and 08/001,736, now U.S. Pat. No. 5,422,653. Of course it should be realized that one or more or even all of the signal processing for the control functions carried out in the image space by the controls  224 ,  205 ,  228  need not be carried out in the image space but could equivalently be carried out in the object space based on raw data available on the line  132  in the object space. 
     The plate  234  may, but need not, be fixedly mounted on a structure (not shown) that, e.g., has fixed structural parts  164  that are indicative of structurally stable parts of a mount for the plate  234  such as an arcade-like booth within which a viewer may be standing or seated for placing the helmet  104  on the viewer&#39;s head for guiding or inducing head movements of the viewer for passive viewing of images gathered in the object space by the cameraman in the helmet  103 . In other words, the seated or standing passive viewer wearing the helmet  104  in the image space  102  is induced or guided to at least emulate pitch, roll and yaw head movements corresponding to the corresponding monitored head movements of the cameraman in the object space, in response to the encoded attitude information in the signal on the line  118 , while at the same time watching corresponding images gathered by the cameras  108 ,  110  also encoded on the line  118  and decoded in the image space for passive viewing. 
       FIG. 13  shows in more detail the image acquisition apparatus in the object space  100  of  FIG. 7 , according to the present invention. The object space  100  of  FIG. 13  shows a cameraman&#39;s head  103   a  which may be inserted in the helmet  103  of  FIG. 7  and may therefore be considered to have a common coordinate system origin. The cameraman&#39;s head is illustrated as having a pair of left and right eyes  14   a ,  14   b  that are monitored by left and right eye monitors  169   a ,  169   b  that provide sensed eye attitude signals on lines  240   a ,  240   b  to respective left and right camera controls  242 ,  244 . These in turn provide camera control signals on lines  246 ,  248  to the left and right cameras  108 ,  110 , respectively. As mentioned, according to the invention, these control signals may, but need not, be used to control the relative position of a region of image nonuniformity including but not limited to a region of increased resolution, dynamic range, or the like, within each of the images provided to the passive viewer in the image space. Such a region is emulative of the increased sensitivity of the fovea of the particular monitored eye along the visual axis thereof. 
     The image space  102  of  FIG. 13  is the same as shown in  FIG. 7  except also showing a variable magnification device  239  which may be used with the display  106  of  FIG. 7  so as to provide images with variable magnification, i.e., at various apparent distances. In other words, the device  239  causes the images from the display  106  to be provided in such a way as to cause the eyes of the viewer to accommodate differently for the various successive images presented thereto. The device  239  may be the same or similar to that shown in copending U.S. patent (application Ser. No. 08/025,975) or in the copending U.S. patent application Ser. No. 08/001,736, now U.S. Pat. No. 5,422,653, particularly in connection with FIGS. 3, 5, 6, 17, 19, 20, 21, and 26-35 thereof. 
       FIG. 11  shows a process that may be carried out in the decoder  220  for decoding the signal on the line  118 . After entering in a step  250 , a step  252  is executed to extract the information encoded on the line  118 . The video information may be decoded first, as indicated in a step  254 . The video signal on the line  222  is then provided from the decoder  220  to the display control  224 . A step  258  may next be executed to decode the helmet attitude data. In a step  260 , the helmet attitude control signal on the line  226  is provided. After that, the previously encoded distance information is decoded in a step  262 , and the variable magnification device control signal on the line  236  is provided in a step  264 . A return is then made in a step  266 . 
       FIG. 14  illustrates the example of a motion-controlled helmet  104  of  FIG. 7  in enlarged detail, according to the present invention. A structure (not shown) such as a stationary arcade-type booth or a moving positional and/or attitudinal simulator such as a vehicle simulator, has the platform  234  mounted fixedly within. This embodiment includes a moveable platform  153  mounted on the inside of the not shown structure, e.g., in the inside top part of a booth structure as an extension thereof. The booth may be designed for having the passive viewer standing or seated. Several pedestals  268 ,  270 ,  272 ,  274  are mounted fixedly on the platform  234 . The moveable platform or plate  153  is controlled in the x-y plane by a pair of orthogonal, screw gear drives  232   a ,  232   c  corresponding to two actuators of the three actuator embodiment of  FIG. 1 . The first screw gear drive  232   a  includes a motor-gear assembly that drives the plate  153  by means of a screw  276  in the plus or minus x-direction. Similarly, the motor-gear assembly  232   c  drives the plate  153  by means of a screw  278  in the plus or minus y-direction. Mounted perpendicularly at the ends of the screws  276 ,  278  are slide bars, such as the slide bar  280  shown at the end of the screw  278 . The slide bar  280 , e.g., is slidably mounted within a slide guide  282  and the screw  278  is attached to a point of the slide bar but can rotate on that point. Similarly, stabilizing rods  284 ,  286  can be installed on opposite sides of the plate  153  with similar slides in slide guides in axial alignment with corresponding screws  276 ,  278  in order to give the control a framework within which to push the plate  153  about in the x-y plane. 
     The third actuator  232   b  turns a gear  288  that turns another gear  290  that has a universal-joint such as shown in  FIG. 15  that has an internal part  292  (see  FIG. 15 ) with a square hole  294  within that accepts a square rod  296  fixed on the helmet  104  for connection thereto, e.g., by slidable insertion therein. The internal part  292  is connected by pins  298 ,  300  (see  FIG. 16 ) to an intermediate part  302  along the x-axis so that the parts  292  and  302  are freely rotatable with respect to each other along the x-axis. The intermediate part  302  is in turn connected to an outer part  304  that has an outside square boundary  306  that fits tightly in a square hole in the gear  290 . The intermediate part  302  is connected to the outer part  304  by pins  308 ,  310  along the y-axis so that the parts  302 ,  304  are freely rotatable with respect to each other about the y-axis. 
     It will be realized that the illustration of  FIG. 14  is for teaching purposes and the motor  232   b  will have to be fixedly attached in some way, e.g., by a bracket (not shown), to the plate  153 . The gears  288 ,  290  are likewise rotatable within casings (not shown) fixed to the plate  153 . The square rod  296  is connected to the U-joint of  FIG. 15  and slides up and down freely through the square hole  294  of the universal joint. Similarly, the rod  296  of the helmet  104  is not shown actually inserted in the universal joint for purposes of clarity. It will also be realized that the universal joint need not take the form shown, since many other u-joints are known, and that even if the form taken is generally the same, the various parts of the universal joint need not be square. The display  106  is shown mounted on the helmet but the display may instead be a panoramic display mounted in a stationary manner with respect to the not shown structure  164 . The three actuators  232   a ,  232   b ,  232   c  are separately responsive to corresponding separate components  230   a ,  230   b ,  230   c  of the control signal  230  of  FIG. 7  for being actuated thereby. 
     It should be realized that the number of axes of control need not be as extensive or could even by more extensive than that shown, since many simplifications or elaborations are quite possible. It was already indicated above that it was not desired, for the preferred embodiment, to control position (translations) per se. It was preferred to leave the control of head positioning to the viewer himself given that his head&#39;s pitch, roll and yaw axes were being so fully constrained. This freedom is granted to the viewer by making the rod  296  freely slidable within the U-joint. Position was therefore divorced from attitude in the preferred embodiment and only attitude was positively controlled. In this way, the viewer could have the freedom to move his head along the axis of the rod  296 . It should be realized, however, that it would be possible to more positively control position, at least to some degree, i.e., with respect to the fixed referent, such as the arcade booth, by simply adding another actuator to the device of  FIG. 14  for retracting or extending the rod  296  (e.g., with teeth added) in or from the U-joint and making some minor modifications thereto. In other words, it should be realized that there are many different ways of connecting or coupling an actuator to a passive viewer&#39;s head for controlling or guiding the movements thereof and the invention is broadly directed to having an apparatus that can be controlled to move a display to guide the passive viewer&#39;s head to allow the viewer to view an image in a manner emulative of a corresponding active viewer&#39;s head movements. It should be realized that the sensed attitude signals of  FIG. 7  need not be actually sensed but can instead be dictated by a pre-planned program of head movements by a workstation  80 . It will therefore be understood that the various devices including actuators shown here are merely illustrative of the invention and many other embodiments are within the scope of the claims. 
     With this in mind, an example will now be given of how to use the sensed head attitude signals from the image space to cause the actuators  232   a ,  232   b ,  232   c  to actuate the helmet, using the exemplary actuator of  FIGS. 7 and 14 , in such a way as to cause the passive viewer to emulate the corresponding attitudinal head movements of the cameraman.  FIG. 17  shows such an example where the platform  234  of  FIGS. 7 &amp; 14  is shown with the x, y, z coordinate system of  FIG. 14  with its x-y origin  312  so placed as to be entered on the platform. Of course, this is just a convenient place to put it and it could be centered elsewhere as well. A point  314  represents the center of the head of the viewer in the helmet  104  in the image space  102  (see also  FIG. 7 ). It may be assumed for purposes of the example that a distance Z 1  between the points  312 ,  314  is constant. This is an approximation good for the case where only three attitudinal axes are positively measured and/or controlled, and not position, as in the exemplary embodiment of  FIG. 7 . It will therefore also be assumed that there is no positional (i.e., translatory) movement of the head origin  314  in the x, y and z directions with respect to the origin  312  and that all the distances x 1 , y 1  and z 1  are therefore constant as well. It should be well understood, however, that more or less than three axes may be positively measured and controlled, including translatory position of the head. In the exemplary embodiment, where only head attitude is of interest and is measured in three axes and similarly controlled in those axes, it may be assumed for purposes of approximation, that the origin of the head of the cameraman/viewer is positionally stationary, i.e., is not translating with respect to the origin  312  of the platform  234 . However, it should clearly be understood that this may not and need not be the case and that the distances x 1 , y 1 , and z 1  between the platform  234  and the origin  314  can be positively controlled and used as a parameter in determining the image to be provided to the eyes of the viewer. This of course implies a sensing of a similar parameter in the object space as previously explained in connection with the steps of  FIG. 9 , for example. This applies to the distances x 1  and y 1  in the x and y axes separately or equally, as desired. 
     In any event, it may be assumed for purposes of approximation for the illustrated embodiment that the head origin  314  is positionally immobile and that, as a result, x 1 , y 1 , z 1  are constant and that the only variables are the sensed pitch, roll, and yaw parameters, as indicated in  FIG. 17  by angles P(y-z plane), R(x-z plane) and Y(x-y plane), respectively. It may be assumed for purposes of visualization and convenience of illustration that the not illustrated viewer in a rest or zero position is sitting or standing erect with his head centered at point  314  and facing in the positive y direction. 
     If it is desired to move the viewer&#39;s head so as to be guided to assume a particular pitch and roll attitude, such as dictated by the signals on the line  230  of  FIG. 7 , the plate  153  of  FIG. 14  will be moved into a position so as to position the universal joint in the gear  290  at a particular position such as centered at a position  316  shown in  FIG. 17 . A shift of minus Δx and positive Δy, as shown, will effect such a change. This will cause the rod  296  to be aligned along an axis  318  intersecting the points  314  and  316  and the viewer&#39;s head will assume the desired pitch and roll attitude at particular pitch and roll angles P, R. Trigonometry can be used to calculate the Δx and Δy movements that will result in the desired pitch and roll angles. For example, if the P angle is determined in the step  152  of  FIG. 9 , as previously described, the step  154  calculates the Δy needed to obtain the desired P angle based on the fixed distance z 1  and the desired angle P. I.e., Δy=z 1  tan P. The actuator  232   c  of  FIG. 14  then causes the platform  153  to move in the positive y direction by the calculated length Δy. 
     Corresponding to the method of  FIG. 9  for the pitch axis, it will be realized that the method of  FIG. 9  can be adapted to apply as well to the roll axis. The illustrated roll angle R is obtained, e.g., by a negative Ax translation of (Δy)(tan R)/(sin P) or, equivalently, Δx=z 1  tan R. The actuator  232   a  of  FIG. 14  may then be used to move the platform a distance of Δx in the negative direction. 
     The third degree of freedom, i.e., the yaw axis may be controlled directly by means of the actuator  232   b  of  FIG. 14 . By turning the gear  288 , the gear  290  and the universal joint within are rotated by the angle Y and the head of the passive viewer is accordingly rotated by the angle Y. 
     Upon induced movement by the apparatus of  FIGS. 14 &amp; 17 , for the illustrated embodiment, the viewer&#39;s head need not stay precisely centered or positioned at point  314  as this is just an approximation. The attitudinal changes of the viewer&#39;s head induced by the apparatus of  FIGS. 14 &amp; 17  will naturally be accompanied by some small translatory movements due to the interaction of the head, neck, and body of the viewer even though the body be relatively stationary. In other words, the rod  296  is able to slide within the U-joint and the viewer can have some control over the translatory position of his head along the axis of the rod  296 . Nevertheless, other embodiments are possible in which the passive viewer&#39;s head position is more precisely controlled. 
     Similarly, it will of course be realized that the known principles of transformation of coordinate systems may be employed to transform and translate the sensed signals in the object space of  FIG. 7  into the coordinate system of  FIG. 17 , as desired. 
     It should also be understood that the attitude control signals on the line  230  of  FIG. 7  change from time to time to cause the viewer&#39;s head to assume various different attitudes. At the same time, it should be understood, correspondingly different attitudinal views of the depicted scene are presented on the display  106  so as to provide a harmoniously changing viewpoint for the passive viewer. In other words, the viewer is made to think that he is viewing a real world object space from different angles as his head is guided in changing attitudes. These different views may be provided by the cameras  108 ,  110  on the cameraman&#39;s head but can be generated by other means  86  such as animation or computer generated imagery. 
     As mentioned above, in connection with  FIGS. 7 &amp; 13 , the signal processor or encoder  116  receives at least one video signal from at least one camera and, in the embodiment illustrated, receives two video signals  112 ,  114  from left and right video cameras  108 ,  110  to provide a stereoscopic video signal to the image space. These signals that are encoded by the signal processor or encoder  116  may be provided to the decoder  220  in the image space  102  so as to provide a viewer with stereoscopic images of the object space. These may be provided by separate displays, one for each eye, or may be provided by the same display alternately, using light shutters, as known in the art of stereo television. 
     As described above, the viewer can be drawn even more deeply into the experience of the cameraman (or a computer generated version thereof) by having his visual axes induced or guided to emulate those of the cameraman. This is not necessary but represents an enhancement of the invention. This is done by monitoring the visual axes of one or more eyes of the cameraman in order to determine the direction of his gaze. That information is then used to produce each image in such a way that it has nonuniform informational content over its expanse. In other words, a portion of each image will have more or less information content concentrated or highlighted therein, in order to draw the attention of the viewer thereto. The particular portion of each successive image that has this extra level of informational content or highlighting will be changed between successive images such that it moves about within the field of view of the viewer according to the direction of the cameraman&#39;s gaze within his field of view and the passive viewer&#39;s eyes will naturally move about in emulation thereof. This sort of a passive viewing of an image nonuniformity, e.g., of a high concentration portion of the image is disclosed in detail in copending U.S. patent application Ser. No. 08/001,736, now U.S. Pat. No. 5,422,653. 
     As also mentioned,  FIG. 13  shows a pair of eye monitors  169   a ,  169   b  that provide sensed signals on the lines  240   a ,  240   b  to left and right camera controls  242 ,  244  which in turn provide left and right camera control signals on the lines  246 ,  248  for controlling the image nonuniformity or high informational content portion of the respective image signals on the lines  112 ,  114 . 
     The nature of the nonuniform images can be selected according to the demands of a given application and need not be of any particular type. They may be of the type shown, for example, in U.S. Pat. No. 3,953,111 by a nonlinear lens or as shown in U.S. Pat. Nos. 4,028,725 or 4,405,943 or 4,513,317 (see FIGS. 2, 3 &amp; 4 in particular) or U.S. Pat. No. 3,507,988 or as shown in the above mentioned copending application U.S. Ser. No. 08/001,736 (nonuniform resolution), now U.S. Pat. No. 5,422,653 or as described below by images having nonuniform dynamic range for the individual pixels therein. Nonuniform resolution images may be provided in analog or digital fashion as described in the copending U.S. patent application Ser. No. 08/001,736 (now U.S. Pat. No. 5,422,653) in connection with  FIGS. 7(   a ),  7 ( b ),  8 - 12 ,  13 ( a )-( c ), and  14  and as described in the accompanying text thereof beginning at page 29, line 3 through page 51, line 14 which is hereby expressly incorporated by reference. Similarly, a nonuniform dynamic range technique may be used in lieu of nonuniform resolution, particularly for digital embodiments. In such a case, a small group of pixels within the total picture are selected to be sensed and/or encoded with a greater number of levels or shades of gray than the larger remainder portion of the total picture. For these pixels, more digital bits are used so as to achieve the greater number of levels. The position of the small group within the total image may be moved as between successive images or within a single image according to the cameraman&#39;s monitored eye movements within the cameraman&#39;s field of view. To carry out the nonuniform imagery, regardless of type, all that is required is that the portion of each successive image that contains the nonuniformity content be presented in such a way as to draw the attention of the viewer&#39;s gaze so that the nonuniform portion falls on the viewer&#39;s fovea. 
     For example,  FIG. 18  shows an object space  320  comprising the interior of St. Ignatius in Rome. A cameraman such as the cameraman of  FIGS. 7 and 13  is located in the object space  320  with a helmet for gathering monocular or stereoscopic images. Assuming the cameraman is seated in the church, as the cameraman moves his head to look about by making attitudinal (pitch, roll, and yaw changes, the camera or cameras pick up the images  322 ,  324 ,  326 ,  328  shown over a short period, e.g., a second or two more or less. It may be assumed that for the first image  322 , the cameraman is seated, with his head level and pointing straight ahead, e.g., pointing in the +y direction of  FIG. 17 . Due to the attitude monitors of  FIG. 7  and the control signals developed therefrom as explained in connection with  FIG. 9 , the display apparatus in the image space will also be oriented so as to cause the passive viewer&#39;s head to be similarly oriented so as to see the same image  322  with his head in the same attitude as that of the cameraman. 
     The images may be provided with uniform resolution. In the particular instance illustrated, however, for the acquired image  322 , the cameraman&#39;s visual axis is not directed straight ahead but off to the left as monitored, e.g., by the oculometer  166  of  FIG. 7  or  180   a ,  180   b  of  FIG. 12  or monitors  169   a ,  169   b    FIG. 13 . As a result, the displayed image has a small area  330  that has higher image informational content than the rest of the image which is shown with fainter lines to indicate a lesser degree of image informational content. The area  330  may be of higher resolution, dynamic range, or the like. The passive viewer&#39;s visual axis is naturally drawn to be directed on the area  330  for viewing by the fovea of the passive viewer&#39;s eye. As a result, the viewer emulates with foveal viewing not only the head movements of the cameraman but also his eye movements. 
     It should be mentioned that if a variable magnification device such as the device  239  of  FIG. 13  is used, the magnification of the image  132  can be changed according to the control signal on the line  238  to change the accommodation of the eyes of the passive viewer. An example of such is shown in  FIG. 20 , where a pair of eyes are shown fixating first at a straight ahead point at a far distance and then at a closer point but off to the side. Thus, the images  134 ,  136 ,  138  to be described below can be viewed with differing accommodation, especially to the extent that they represent objects at differing distances as indicated by the eye monitor or monitors  169   a ,  169   b . In this way, the variable magnification device is responsive to light from the light source and to a variable magnification control signal, for changing the apparent distances of the images. It should be realized that the changing of the apparent distances can also be accomplished by changing the actual distance of the display, in response to a control signal. It should also be realized that the degree of accommodation experienced in the eyes of the viewer can be coordinated with convergence of the eyes so as to maintain a selected relationship therebetween, preferably a normal relationship, e.g., as shown in  FIG. 19  of copending application Ser. No. 08/462,503. 
     The cameraman next moves his head up and to the left, i.e., executes a clockwise movement (pitch) in the y-z plane and a counterclockwise (viewed from above) movement (yaw) in the y-x plane of  FIG. 17 . The acquired image  324  is the result. It will be observed that the cameraman&#39;s visual axis has changed its point of attention within the object space to a small area  332  on a lower right hand side of “his’ field of view. The display apparatus in the image space of  FIG. 7  will cause the passive viewer to execute similar attitudinal head movements. Similarly, the passive viewer&#39;s eyes are naturally drawn to the small area  332  for viewing by the fovea of the passive viewer&#39;s eye. If the small area  142  is or should be represented at a different distance than the area  140  then the variable magnification device may be used to cause a differing accommodative response. 
     The cameraman next moves his head up and to the right, i.e., executes a clockwise movement (pitch) in the y-z plane and a clockwise movement (yaw) in the y-x plane and acquires the image  326 . the cameraman&#39;s visual axis in this case is still directed to the right but slightly above to a small area  334  of higher image informational content. The display apparatus in the image space of  FIG. 7  will cause the passive viewer to execute similar attitudinal head movements. Similarly, the passive viewer&#39;s eyes are naturally drawn to a small area  334  for viewing by the fovea of the passive viewer&#39;s eye. And if a change in accommodation is appropriate, such can be controlled according to the device  239  of  FIG. 13 . 
     Finally, the cameraman next moves his head further up and to the right, i.e., executes a clockwise movement (pitch) in the y-z plane and a clockwise movement (yaw) in the y-x plane and acquires the image  328 . The cameraman&#39;s visual axis in this case is still directed to the right but slightly down to a small area  336  of higher image informational content. The display apparatus in the image space of  FIG. 7  will cause the passive viewer to execute similar attitudinal head movements. Similarly, the passive viewer&#39;s eyes are naturally drawn to the small area  336  for viewing by the fovea of the passive viewer&#39;s eye and appropriate accommodative changes can be induced. The illustrated head movements then continue in a similar way. 
     Although no roll movements (in the x-z plane) have been illustrated (as a tilt) in  FIG. 18 , such are of course contemplated, according to the invention. It should be realized that the images gathered in the object space and presented in the image space succeed each other at a very rapid rate, e.g., 30, 60, 120 or even more frames per second. Thus, for the illustration of  FIG. 18  there will likely be a multitude of images presented beyond the few shown so that the sequence or presentation of images is much smoother than indicated. 
     As already indicated in connection with  FIG. 7 , the images gathered in the object space may be stereoscopic. Such may be presented by the display in the image space of  FIG. 7  in any convenient stereoscopic format of uniform or nonuniform resolution presentation. For a narrow field of view such as shown in  FIG. 18  (e.g., on the order of 30-45 degrees) the stereopair images are completely overlapped and still only cover half of the full 90 degrees of binocular vision of the human visual process. An Asher-Law stereoscope as taught in FIGS. 20-22 of copending application Ser. No. 08/462,503 would be a suitable means of presentation as described at page 64, line 24 through page 68, line 8 which is hereby incorporated by reference. 
     As shown in copending application Ser. No. 08/462,503, based on U.S. Ser. No. 08/1,736, now U.S. Pat. No. 5,422,653, a stereopair may be partially overlapped as described at page 57, line 6 through page 63, line 20 and as shown in FIGS. 17 and 18( a )-( d ) with separate very narrow field of view areas of high image informational content in the separate left and right views coinciding and moving about together within an area of binocular overlap. Such an approach is particularly appropriate where an overall very wide field of view is presented, e.g., wider than 90 degrees, i.e., where the areas outside 90 degrees are monocular, in imitation of the human field of view. Such wide angle images can be acquired with a high degree of detail over the full field of view of the human visual apparatus using an array of image sensor modules such as shown in U.S. Pat. No. 4,323,925. Or, a pair of virtual retinal displays such as shown in U.S. Pat. Nos. 5,467,104, 5,596,339, or 5,574,473 can be used. The degree of detail achieved, however, is chiefly important in the area of stereoscopic foveal viewing. 
     For example, as shown in  FIG. 19 , a sequence of four stereoscopic images  338 ,  340 ,  342 ,  344  similar to the sequence of  FIG. 18  are shown, each comprising corresponding overlapping left and right halves  338   a ,  338   b ;  340   a ,  340   b ;  342   a ,  342   b ;  344   a ,  344   b . Each half represents the field of view of a respective left or right eye. Each can have a horizontal field of view of as wide as 140 degrees, approximately corresponding to the full human monocular field. An inverted triangular shaped area of overlap of each pair is viewed stereoscopically, i.e., binocularly and can be as wide as 90 degrees horizontally corresponding to the full horizontal extent of human binocular overlap. As in  FIG. 18 , the images sequence from the bottom to top of the Figure with an accompanying sequence of head movements. Within each triangular shaped area of binocular overlap in each pair are two overlapping areas of high concentration image information  338   c ,  340   c ,  342   c ,  344   c . Since these are overlapping in the Figure, they appear as one. They are similar to those shown in  FIG. 18  except for being indicative of binocular foveal fusion. 
     For thus viewing stereo images by two eyes, the light control signal contains information for providing light for viewing stereo images having a portion with high informational content and a portion with low informational content and wherein the portion with high informational content changes position within the images for foveal viewing by the two eyes by following the position changes. If it is desired to include one or a pair of variable accommodation devices, such can be used to change the accommodation of the two eyes either together or independently. Moveover, the light control signal can contain information for providing the light for viewing stereo images having a portion with high informational content and a portion with low informational content and wherein the portion with high informational content changes position within the images for foveal viewing by the two eyes by following the position changes at correspondingly changing convergence, i.e., at correspondingly changing visual fixation points. In other words, the visual axes of the eyes will intersect at varying points in a three-dimensional image space. The accommodative changes to be induced at each such fixation point can be controlled for each eye independently, or for both eyes to the same degree. Independent treatment is more important at close fixation point distances. This is because the distance from one eye to the point of fixation may be markedly different from that of the other. Such occurs primarily when a close fixation point is markedly off to one side or the other of the viewer&#39;s field of view. 
     It may be the case that eye tracking in the object space is not desired but that an emphasis of the binocular area of overlap is nonetheless wanted. In that case the area of high resolution emphasis can be enlarged, e.g., as shown in  FIG. 21  to cover the entire area of binocular overlap in a sequence similar to those shown in  FIGS. 18 &amp; 19 . In such a case, no matter where the viewer chooses to fixate within the binocular overlap area he will view the imagery with a high level of resolution. This would eliminate the need for controlling the position of a small area of high informational content by eye monitoring or the like while at the same time reducing the informational content in the areas of nonoverlap of the monocular fields, albeit with the loss of full control of simulation of active percepts for passive viewing. Similarly, a central, fixed area of each of the images  FIG. 18  could be rendered with higher informational content or highlighted in a selected manner. 
     As already suggested above, it may also be useful to provide the image to the viewer at various apparent distances as shown for example in copending application U.S. Ser. No. 08/25,975 at page 6, line 25 through page 32, line 10 by means of a variable magnification device such as shown (but not limited to) in copending application having U.S. Ser. No. 08/1,736 at page 24, line 23 through page 29, line 2 in connection with FIGS. 3-6 thereof, and at page 70, line 11 through page 72, line 2 in connection with FIGS. 26-35 thereof, all of which is hereby expressly incorporated by reference. 
     For a virtual retinal display, on the other hand, all the objects can be represented at the same time at their various apparent distances by appropriate defections of the scanning light beam, e.g., by actuating lenses and mirrors for providing the light beam from a selected trajectory for each pixel impinging on the retina of the viewer. In that case, according to the present invention, the eyes of the passive viewer can be induced to follow a selected series of visual fixations by “painting” only a small portion of the scene with a fine light beam and the rest a coarse beam. The viewer&#39;s eyes will then be induced to turn their foveas in the direction of the fine portion of the scene. 
     In connection with any of these various types of images, as also suggested above, it may be desired to present the images to the eyes of the viewer at various apparent distances in such a way as to preserve a selected relationship such as, but not necessarily, a normal relationship between accommodation and convergence in the eyes of the viewer. Such is shown, for example, beginning with FIG. 19 and as described beginning at page 63, line 21 through page 68, line 8 and in further connection with FIGS. 20-22 of the above mentioned U.S. Ser. No. 08/1,736, now U.S. Pat. No. 5,422,653, which is incorporated by reference. For a virtual retinal display as modified as described above, the effect is automatic, assuming the representative of apparent distances is accurate. Merely by being induced to fixate on a point at the desired distance, the eyes of the passive viewer accommodate and converge harmoniously, in a normal manner. 
     The helmet mounted display of the image space of  FIG. 1  can take the form as shown, for example, in FIGS. 23-25 of U.S. patent application Ser. No. 08/1,736 as described beginning at page 68, line 9 through page 70, line 10, now U.S. Pat. No. 5,422,653, which is incorporated by reference. 
     Similarly, although not disclosed herein, it should be realized that an audio component of the video signal on the line  226  may be provided as well by placing microphones in the object space such as positioned in strategic locations on the cameraman&#39;s head. Similarly, speakers may be provided in the image space and located in analogous positions about the head of the viewer for receiving decoded audio signals from the decoder. I.e., the speakers may be placed strategically about the helmet for reproducing sound as if from three dimensions as heard by the cameraman. Such is shown in detail in (copending application Ser. No. 08/1,736) U.S. Pat. No. 5,422,653 at col. 29 (page 52), line 4 (18 through col. (page 57), line (5) in connection with  FIG. 16  and at col. (page 68), line (14) through col. (page 69), line (7) in connection with  FIG. 23 , all of which is hereby expressly incorporated by reference. 
     Although most of the embodiments shown thus far show the user in a standing or otherwise semi-erect position in a chair, it should be realized that the invention is applicable to a more relaxed position for the user. For instance,  FIG. 22  shows a support  402  for supporting the body of a user and more particularly for supporting a moveable headrest  404  for supporting the back of the head  406  of the user in executing head movements while viewing images provided by a display  408  from a changing direction, i.e., a changing “direction-of-view,” according to the invention. In other words, the direction, i.e., attitude of the head of the viewer actively changes or is passively changed for viewing images from a correspondingly changing direction. In the case where the moveable headrest is moveable by the user actively changing the direction of his head, i.e., under his own volition, the movements are monitored by a sensor  410  for the purpose of providing an input signal on a line  412  to a reality engine (see  FIGS. 32 and 33 ) for selecting the images according to the changing direction. In the case where the attitude of the head of the user is passively changed, the moveable headrest is moveable by an actuator  414  to change the “direction-of-view” of the head of the user in response to a command signal on a line  416  from a reality engine (see  FIGS. 34 and 35 ) with the images changing their direction-of-view correspondingly, according to an image signal from the reality engine. Although the display  408  is shown adjacent the head  406 , it should be realized that it can be apart from the head. 
       FIG. 23  shows a user  417  reclining on a support in the form of a recliner  402   a  equipped with a moveable headrest  404   a  with a rod  20  supported by a support  418  that is attached to or part of the support  402   a . The support  418  may comprise brackets  422  through which the rod  420  is threaded. The rod may come to rest or be fixedly terminated on a stop  424 . The head  406   a  of the user in a reclining position rests on the headrest  404   a  for viewing images from a changing direction-of-view provided by a display  408   a  which may be any kind of display. One of the many types of display that may be used is a head mounted display such as shown in U.S. Pat. No. 5,671,037. Although the recliner  402   a  is shown as a stationary support, it can be of the type preferably as shown in U.S. Pat. No. 5,695,406 but also as shown in other chair type simulators such as, among others, U.S. Pat. Nos. 6,056,362, 5,678,889, 3,628,829, 5,490,784, as well as others filed after the Mar. 13, 1999 US parent (60/124,642) of the present application such as U.S. Pat. Nos. 6,152,828 or 6,113,500. In such cases, the translations determined in the steps of  FIG. 9 , particularly accelerations associated therewith, can be used to control the chair or other platform. 
     It should be realized that although the moveable headrest is shown supported by a support  402  which may also support the body of the user, the body of the user need not be supported by the support  402  but may be supported in some other way. In other words, the moveable headrest may equivalently be supported by a support that is different from the support provided for supporting the body of the user. For instance, the headrest might be wall-mounted and the user support positioned nearby to allow the head of the supported user to rest on the headrest in the same way as shown above while the user may lean against or stand next to the wall. 
     For another instance,  FIG. 24  shows a user  417   b  secured in a standing position on a support  402   b  in the form of a human activity simulator such as shown in U.S. Pat. No. 5,792,031. The simulator is equipped, according to the present invention, with a moveable headrest  404   b  for supporting the head of the user while viewing images provided by a display  408   b  from a changing direction. 
     In yet another instance,  FIG. 25  shows a user  417   c  seated on a support in the form of a chair  402   c  equipped with a moveable headrest  404   c  while viewing images provided by a display  408   c  from a changing direction, according to the invention. Although the chair  402   c  is shown as a stationary support, it can be of the type shown in U.S. Pat. No. 5,642,302, modified appropriately to be continuously positionable, as in the recliner of U.S. Pat. No. 5,695,406. 
       FIG. 26  shows a moveable headrest  404   d  with a pivotal support assembly for supporting the head  406   d  of a user in executing head movements with a changing direction-of-view while viewing images from a correspondingly changing direction-of-view. Except for the display  408   d , an actuator  426 , a sensor  428  and a supporting bracket  430 , the hardware for the headrest structure shown in  FIG. 26  and described below is taken from U.S. Pat. No. 5,791,735 of Helman entitled “Headrest assembly with user actuated pivotal support assembly.” The Helman headrest is for attachment to a wheelchair seating system for use in supporting and assisting with movements of the head of a patient with weak neck muscles. It includes a cushioned backpad  432 , a pair of laterally spaced apart cushioned side pads  434 , and a mounting assembly  436  located substantially to the rear of said headrest. The mounting assembly  436  enables the backpad and the sidepads to rotate together as a unit about a vertical axis located forward of the mounting assembly. The mounting assembly is formed such that the vertical axis of rotation of the assembly substantially coincides with the spinal column of the human patient seated in the wheelchair. The rotational range of backpad  432  and sidepads  434  is manually adjustable and limited to a prescribed range. A force is formed with a rubber band  435  resisting rotational displacement in said backpad  432  and sidepads  434  returning said headrest to a null, forward facing orientation. The strength of the force increases with a corresponding increase in rotational displacement of the headrest. For the purposes of the present invention, the headrest assembly can be used to support the bead of a user while viewing images from a controlled location. 
     To enable cushions  432 ,  434  to be positioned so that they best fit the particular user&#39;s head  406   d , pivoting assemblies  438  connect the support cushions  432 ,  434  to structural members  440 ,  442 , respectively. The pivoting assemblies  438  are composed off a ball and socket type joint which allows pivoting of cushions  432 ,  434 . This pivoting action allows cushions  432 ,  434  to be tilted and oriented such that they best firmly contact the head of the particular user supported as shown e.g. in  FIGS. 23-25 , thus accommodating different shapes and sizes of heads of different users. It should be realized that the left sidepad  434  is shown unpivoted in  FIG. 26  in order to show the pivoting assembly. With a human head resting against the sidepad  434  it will be tilted downward to engage the bottom of the skull of the head  406   d  as suggested by the dashed line  437 . An additional pivoting assembly  444  connects extension member  440  to the mounting assembly  436 . The mounting assembly  436  extends rearwardly of the backpad  432  and the sidepads  434  to a support mounting structure  446 . Pivoting assembly  444  is composed of a ball and a socket type joint. Pivoting assembly  444  permits cushion  432  to be moved in a back and forth direction thus enabling even greater flexibility in positioning cushion  432  to the particular shape of the user&#39;s head. Side cushions  434  may also be adjusted in a back and forth direction since structural members  442  are received in a vice type bracket  448  which holds structural members  442  in place. Bolts  450  in brackets  448  can be loosened such that structural members  418  can be slid the slightly forward and backward, thus giving another dimension of movement in positioning cushions  434 . After adjusting structural members  442  to the particular head shape of the user, bolts  450  are tightened in place fixing the side cushions  434  in position. Operating together, cushions  432  and  434  provide comfortable support to the rear and sides on the user&#39;s head. Balancing for the user&#39;s head is also provided by these supporting cushions. 
     The Helman headrest assembly provides support and balancing to the user&#39;s head not only when it is stationary, but also through limited degrees of motion. To accomplish this, the supporting cushions  432 ,  434  must be able to move with the rotation of the head. The mechanism to accomplish this function is found in the design of mounting assembly  436  which guides the motion of the cushions  432 ,  434 . Mounting assembly  436  comprises a plurality of four forwardly extending arms  452 ,  454 ,  456 ,  458  which together comprise a linkage assembly. The movement of these forwardly extending arms with respect to one another allows the user to have freedom to rotate his head to a limited degree. The method of functioning of the forwardly extending arms  452 ,  454 ,  456  and  458  is explained in more detail in the above-mentioned U.S. Pat. No. 5,791,735 of Helman which is hereby incorporated by reference. Suffice it to say that connectors  460 ,  462 ,  464  separate the various forwardly extending arms  452 ,  454 ,  456 ,  458  and enable these arms to pivotally rotate freely about the points through which the respective connector passes. 
     As mentioned above, the user is equipped with a display  408   d , according to the present invention, which provides images from a changing direction-of-view in correspondence with a changing direction-of-view of the head  6   d  of the user. The user&#39;s head is supported and/or guided from the rear and the user can consequently assume a relaxed posture. The display need not be of the goggle type shown in  FIG. 26 , but may be of any type.  FIG. 27  shows the user with his head  406   d  oriented in a straight-ahead looking direction for viewing a central rotund part of the US Capital Building in silhouette with a certain field-of-view. In  FIG. 28 , the field-of-view has been shifted left for viewing the left-hand side of the U.S. Capital Building. In  FIG. 29 , the field-of-view has been shifted right for viewing the right-hand side of the U.S. Capitol Building. 
     Depending on the design, the display can be used actively only, passively only, or in a dual mode version either actively or passively.  FIG. 26  shows a design in which the headrest assembly of Helman can be used either actively or passively. This is accomplished by providing both a motor  426  and a sensor  428  on the bracket  430  which is rigidly attached to the mounting structure  446 . The shaft of the motor and sensor may be axially coupled and fixed to the arm  454  for rotating the arm  454  about the common axis of the motor and sensor. This causes rotations of the other arms  452 ,  456 ,  458 , which are shown in more detail in U.S. Pat. No. 5,791,735 of Helman. The motor  426  may be a stepping motor, a servo motor, or the like, for use in a passive mode of operation to actuate the headrest assembly in executing headrest movements such as illustrated in  FIGS. 27-29  for guiding the head  406   d  of the user. In that case, the sensed output signal from the sensor  426  may be unutilized (open loop control) or may be used as a feedback signal (closed loop control). An open loop control is shown in  FIG. 30  with the command signal on the line  416  provided to a simple proportional amplifier that in turn provides an amplified output signal on a line  416   a  to the actuator  414 . On other hand, the sensor  428  may be used in an active mode of operation to sense movements of the headrest assembly such as illustrated in  FIGS. 27-29  as actuated by the volitional movements of the user&#39;s head  6   d . The sensor may be an RVDT or rotary potentiometer, for instance, for sensing angular displacement. A closed loop control is shown in  FIG. 31  with the command signal on the line  416  provided to a summing junction where the sensed signal on the line  412  is subtracted therefrom. A difference signal is provided by the summer to a compensator such as a proportional-integral (P-I) compensator that in turn provides a compensated output signal on a line  416   b  to the actuator  414  such as the motor  426 . 
       FIG. 32  shows hardware setup for active use of the moveable headrest, i.e., with the user moving his head at will. A sensor  410   a  provides a senses signal on a line  412   a  to a local reality engine  470   a  which, in response thereto, retrieves an image sequence from a memory therein having a plurality of such stored sequences. The signal ont he line  412   a  is comparable to the signal on the line 28 of FIG. 3 of U.S. Pat. No. 5,644,324. The retrieved sequence is provided on a line  472   a  to a display  408   a  for viewing by the active user. The reality engine  408   a  may be embodied in a local computer or a remote computer accessible through a network  474   b , as shown in  FIG. 33 . In the example of  FIG. 32 , the active user moves his head and the headrest follows. The sensor  410   a  senses the angular rotation of the headrest and provides the sensed signal on the line  412   a  to the reality engine  470   a  which in turn provides the retrieved sequence on the line  472   a  to the display  408   a . The retrieved sequence of images are taken from different directions of view, corresponding to the viewer&#39;s active head movements. The images are presented from differing directions of view according to the active user&#39;s head movements to make him feel that he is moving his head and viewing the virtual world in the same way he views the real world.  FIG. 33  is the same as  FIG. 32  except that the reality engine  470   b  is remote and is accessed via a network  474   b . The reference numerals are similar to those of  FIG. 32  except with the “be” suffix. 
       FIG. 34  shows passive use of the moveable headrest with an actuator  414   c  moving the headrest and hence the user&#39;s head in response to a signal on a line  416   c  from a local reality engine  470   c . The signal on the line  416   c  is comparable to the signal on the line 20 of FIG. 1 of U.S. Pat. No. 5,734,421. The sensor  490   c  provides the sensed signal on the line  412   c  to the local reality engine  470   c  as a feedback signal, for closed loop control. For a headrest that is only to be used for passive users, it should be realized that a sensor is not absolutely necessary since open loop control of the headrest will work. In the case of passive use, the reality engine retrieves a single, preplanned image sequence from a memory therein, in response to a start command signal on a line  476   c . The start command signal on the line  476   c  can originate with the passive viewer pressing a button, voicing a speech command, having his eyes monitored, by some combination of such commands, or the like. The retrieved sequence is provided on a line  472   c  to a display  408   c  for viewing by the passive user. The reality engine  470   c  may be embodied in a local computer or a remote computer accessible through the network  474   d , as shown in  FIG. 35 .  FIG. 35  is the same as  FIG. 34  except the reality engine is remote and accessed via a network  474   d . The reference numerals in  FIG. 35  are similar to those of  FIG. 34  except having the suffix “d”. 
     Referring back to the variable magnification device  239  of  FIG. 13 , it should be pointed out that the provision of successive images to the eye at varying apparent distances for viewing with correspondingly varying focus (accommodation) creates a granularity problem. With increasing focus, because of the limitations of man-made imaging technology, there is not any increased level of granularity available for inspection. Therefore, there can be a problem with the simulated reality of the imagery under increased focus. As suggested, the granularity of a given static man-made image of a real object is only as good as that of the imaging technology used to acquire and present it. Closer inspection with a magnifying glass or other aid to eyesight does not ultimately reveal any deeper granularity but only the limitations of the imaging technology used. This is not usually a problem for images in books, movies and other conventional media. 
     On the other hand, the granularity of real objects is unlimited as far as the human eye is concerned. Considering the eye itself, with increased focus, more detailed granularity of objects is always revealed. Moreover, with technological aids to the eye, e.g., the magnifying glass, the optical microscope, the electron microscope, and other tools, smaller details are always revealed. 
     Referring back to the cameras  108 ,  110  of  FIGS. 7 ,  12  and  13 , these can be equipped with lenses that vary the focal length according to a control signal. For instance, as shown in  FIG. 36 , one of the cameras  108 ,  110  of  FIGS. 7 ,  12  and  13  is shown collecting images of a scene  432  illuminated by a light source  434 . An eye  436  of the cameraman of  FIG. 7  is shown using an eyepiece  438  for viewing the scene  432  being photographed. A sensor  440  which may take the form of one of the eye monitors  169  of  FIG. 13  such as does an eye accommodation sensor senses the accommodation of the eye  436 . The sensor  440  provides a sensed signal on a line  442  to an optic control  444 . The optic control  444  provides a camera optic control signal on a signal line  446  to, e.g., a motorized camera optic  448 . A motorized optic is for example only and could take other forms. The optic control  444  causes the motorized optic  448  to focus on the scene  432  at differing focal lengths according to changes in the accommodation, direction, or the like, of the eye  436  as detected by the sensor  440 . The optic  448  casts rays  450  on to an image sensor  452  that provides a video image signal on a line  453  to a combiner  454 . It combines, e.g., in a time division multiplexed way, the image signal on the line  453  with the signal on the line  442  to form the video data signal on the line  118  of  FIG. 7 . As explained above, the signal on the line  442  could be provided in parallel on a separate signal line alongside the signal on the line  222 . In that case, it would only carry video information. 
     Referring now to  FIG. 37 , an apparatus  510  is there shown for showing images to an eye  512  of a passive viewer such as the eye  14  of  FIG. 1  or an eye of a user of the devices of  FIGS. 2A ,  2 B,  3 ,  4 ,  7 ,  23 ,  24 , or  25 . A video signal is received on the line  118  by a control  516  similar to the controls  224  and  205  of  FIG. 7 , for example. The video signal contains image information which is decoded and provided on a signal line  518  to for instance an image projector  520  which projects images with first light rays  522  to a first optic  524 . The first optic  524  may for instance be a lens that is under the control of a control signal on a line  526  from the control  516 . The control signal on the line  526  is decoded by the control  516  from the video signal on the line  118 . The first optic  524  refracts or otherwise bends the light rays  522  into second light rays  527  that are projected on to a screen such as a translucent screen  28  to form images of different sizes, i.e., that fill the screen  28  to a greater or lesser extent as shown in  FIGS. 38-40 , as discussed below. The signal on the line  118  can be provided in many different ways. For instance, it should be realized that the signal on the line  118  need not be a single line (which implies some form of multiplexing) but could be two or more signal lines. 
     It will also be realized from the foregoing that the control signal on the line  526  changes the projected first light rays  522  by means of the optic  524  according to changes detected in the cameraman&#39;s eye  436  of  FIG. 36  by the sensor  440 . In other words, the signal on the line  442  from the sensor  440  is not only used to control the optic  448  in the object space of  FIG. 36 , but is also used to control the optic  524  in the image space of  FIG. 37  after transmission to the image space over the signal line  118 . The nature of the change in the projected first light rays  522  is manifested by the manner in which the light rays  527  are projected on to the screen  528 . It should be realized that the rays  527  would be reflected from a mirror before being sent to the screen  528  which could be reflective rather than transmissive. Such would result in a folded embodiment rather than the straight system shown. The examples of  FIGS. 38-40  have already been referred to. If the eye  436  of  FIG. 36  is detected by the sensor  440  viewing the scene  432  with a long focal distance, such as infinity, the optic control  444  causes the optic  448  to focus on a correspondingly long distance. The optic  448  focuses the scene  432  at infinity and projects the details of the scene with a wide field of view on to the image sensor  452 . Consequently, the available sensor  452  pixels are spread over a relatively wide field of view. In other words, the granularity of the image is spread over a wide field of view.  FIG. 38  shows the second light rays  527  projected to form an image  554  that fills or almost fills the entire area or extent of the screen  528 . 
     If the eye  436  of  FIG. 36  is detected by the sensor  440  viewing the scene  432  with a lesser focal distance such as an intermediate focal distance, the optic control  444  causes the optic  448  to focus at a correspondingly intermediate distance. The optic  448  focuses the scene  432  at the intermediate distance and projects the details of the scene with an intermediate field of view on to the image sensor  452 . Consequently, the granularity, i.e., the available sensor pixels are spread over a relatively intermediate field of view.  FIG. 39  shows the second light rays  527  projected to form an image  556  that only partially fills the entire extent of the screen  528 . 
     If the eye  436  of  FIG. 36  is detected by the sensor  440  viewing the scene  432  with a short focal distance, the optic control  444  causes the optic  448  to focus at a correspondingly short distance. The optic  448  focuses the scene  432  at a correspondingly short distance and projects the details of the scene with a narrow field of view on to the image sensor  452 . Consequently, the available sensor pixels are spread over a relatively narrow field of view. Particular objects within the narrowed field of view of  FIG. 40  can be viewed with more granularity than those same objects could be with the granularity provided by that of  FIG. 39  and even more so than that of  FIG. 38 .  FIG. 40  shows the result of the second light rays  527  projected to form an image  558  that only fills a small extent of the entire extent of the screen  528 . 
     Referring back to  FIG. 37 , as explained above, the second light rays  527  are projected on to the screen  528  with different areas or extents  554 ,  556 ,  558 , all of which have the same total number of pixels. These are transmitted as a third bundle of rays  529  to an optic  560 . The advantage of this feature of the invention is that with the aid of the optic  560 , the field of view of the eye  512  of the viewer can be fully occupied with all of these pixels even though the accommodation of the eye changes. The total number of pixels can be spread over the full extent of the retina in all cases by a combination of changes in the focal length of the optic  560  and the accommodation of the eye  512 . When the optic  448  focuses in on a detail of the wider scene  432 , it increases the granularity of the imaged scene in that area. At the same time, the optic  524  causes the size of the image to be reduced on the screen  528  as shown, e.g., in  FIG. 39  or  40 . In other words, when the focal length of the optic  448  is shortened to capture a narrowed field of view of the scene  432  with increased magnification, the granularity of that smaller portion of the imaged scene increases as manifested in a smaller area on the screen  528  as controlled by the optic  524  and signal  526 . At the same time, the focal length of the optic  560  is controlled by a control signal on a line  564  from the control  516  to allow the eye  512  to accommodate, i.e., to focus closer on to the scene with increased granularity in the area of interest. In other words, at the same time that the control signal on the line  526  causes the optic  524  to reduce the extent to which the screen  28  is filled by imagery (see  FIG. 39  or  40 ), the signal on the line  564  causes the optic  560  to reduce the field of view provided for the eye  512 , e.g., by increasing its magnification. Thus, the optic  560  refracts third rays  529  to provide fourth light rays  564  in such a way that the eye  512  must change its accommodation so as to bring the image into focus on the reduced size imagery. This causes the field of view of the eye  512  to be reduced but fully occupied with an up-close image while taking full advantage of the available granularity. 
     If the cameraman&#39;s eye  436  changes to a long view of the scene  432 , as explained above, the image  554  fills the screen  528  because of the control signal on the line  526  causing the optic  524  to expand the extent to which the screen  28  is filled by imagery. At the same time, the signal on the line  564  causes the optic  560  to expand the field of view provided for the eye  512 , e.g., by reducing its magnification or increasing its focal length. The eye  512  changes its accommodation accordingly. In other words, when the control signal on the line  526  causes the optic  524  to increase the extent to which the screen  24  is filled by imagery, as in  FIG. 38 , the signal on the line  564  causes the optic  560  to increase the field of view provided for the eye  512  even further, e.g., by decreasing its magnification even more. 
     Similarly, although the invention has been shown and described with respect to a best mode embodiment thereof, it should be understood by those skilled in the art that various changes, omissions and deletions in the form and detail of the foregoing may be made therein without departing from the spirit and scope of the invention.