GB2517008A

GB2517008A - Head-mountable apparatus and systems

Info

Publication number: GB2517008A
Application number: GB1404740.1A
Authority: GB
Inventors: Simon John Hall; Jeremy David Ashforth; Darren Myatt
Original assignee: Sony Computer Entertainment Europe Ltd
Current assignee: Sony Interactive Entertainment Europe Ltd
Priority date: 2013-06-11
Filing date: 2014-03-17
Publication date: 2015-02-11
Also published as: GB201314967D0; GB201310358D0; GB201404740D0

Abstract

A head mountable display (HMD) has a camera that captures images of a peripheral and/or control device in use by the wearer of the HMD. The HMD then renders a virtual item to be displayed on the HMD in an image position based on the detected position of the peripheral and/or control device. The virtual image may be virtual video screen or a menu, and the control device provides user control of the menu or video screen. The image may be centred on the detected position of the control device. The virtual image may be rendered in 2D or 3D to appear flat or curved. The virtual item may be telephone or a keyboard. The system may provide haptic feedback via the peripheral and/or control device.

Description

HEAD-MOUNTABLE APPARATUS AND SYSTEMS

This invention relates to head-mountable apparatus and systems.

A head-mountable display (HMD) is one example of a head-mountable apparatus.

Audio headphones comprising a frame supporting one or more audio transducers are another example of a head-mountable apparatus. A head-mounted torch or light is a further example of a head-mountable apparatus. The following background discussions will relate mainly to HMD5, but the principles are also applicable to other types of head-mountable apparatus.

In an HMD, an image or video display device is provided which may be worn on the head or as part of a helmet. Either one eye or both eyes are provided with small electronic display devices.

Some HMDs allow a displayed image to be superimposed on a real-world view. This type of HMD can be referred to as an optical see-through HMD and generally requires the display devices to be positioned somewhere other than directly in front of the user's eyes.

Some way of deflecting the displayed image so that the user may see it is then required. This might be through the use of a partially reflective mirror placed in front of the user's eyes so as to allow the user to see through the mirror but also to see a reflection of the output of the display devices. In another arrangement, disclosed in EP-A-1 731 943 and US-A-2010/0157433, a waveguide arrangement employing total internal reflection is used to convey a displayed image from a display device disposed to the side of the user's head so that the user may see the displayed image but still see a view of the real world through the waveguide. Once again, in either of these types of arrangement, a virtual image of the display is created (using known techniques) so that the user sees the virtual image at an appropriate size and distance to allow relaxed viewing. For example, even though the physical display device may be tiny (for example, 10 mm x 10 mm) and may be just a few millimetres from the user's eye, the virtual image may be arranged so as to be perceived by the user at a distance of (for example) 20 m from the user, having a perceived size of 5 m x Sm.

Other HMDs, however, allow the user only to see the displayed images, which is to say that they obscure the real world environment surrounding the user. This type of HMD can position the actual display devices in front of the user's eyes, in association with appropriate lenses or other optical components which place a virtual displayed image at a suitable distance for the user to focus in a relaxed manner -for example, at a similar virtual distance and perceived size as the optical see-through HMD described above. This type of device might be used for viewing movies or similar recorded content, or for viewing so-called virtual reality content representing a virtual space surrounding the user. It is of course however possible to display a real-world view on this type of HMD, for example by using a forward-facing camera to generate images for display on the display devices.

Although the original development of HMDs was perhaps driven by the military and professional applications of these devices, HMD5 are becoming more popular for use by casual users in, for example, computer game or domestic computing applications.

Various aspects and features of the present invention are defined in the appended claims and within the text of the accompanying description and include at least a head mountable apparatus such as a display and a method of operating a head-mountable apparatus as well as a computer program.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 schematically illustrates an HMD worn by a user; Figure 2 is a schematic plan view of an HMD; Figure 3 schematically illustrates the formation of a virtual image by an HMD; Figure 4 schematically illustrates another type of display for use in an HMD; Figure 5 schematically illustrates a pair of stereoscopic images; Figures 6 and 7 schematically illustrate a user wearing an HMD connected to a Sony® PlayStation 3® games console; Figure 8 schematically illustrates a change of view of user of an HMD; Figures 9a and 9b schematically illustrate HMD5 with motion sensing; Figure 10 schematically illustrates a position sensor based on optical flow detection; Figure 11 schematically illustrates the generation of images in response to HMD position or motion detection; Figure 12 schematically illustrates an example peripheral device; Figure 13a schematically illustrates the device of Figure 12 as viewed by the camera of the HMD; Figure 13b schematically illustrates an image area based on a detected image position of the device of Figure 12; Figure 14a schematically illustrates a video screen rendered at the image position of Figure 13b; Figure 14a schematically illustrates a control menu rendered at the image position of Figure 13b; Figure 14c schematically illustrates a variation in the rendering of Figures 14a or 14b, according to the orientation of the device of Figure 12; Figure 15 schematically illustrates part of the functionality of an HMD; and Figure 16 schematically illustrates part of the functionality of a hand held peripheral device.

Referring now to Figure 1, a user lOis wearing an HMD 20 (as an example of a generic head-mountable apparatus -other examples including audio headphones or a head-mountable light source) on the users head 30. The HMD comprises a frame 40, in this example formed of a rear strap and a top strap, and a display portion 50.

Note that the HMD of Figure 1 may comprise further features, to be described below in connection with other drawings, but which are not shown in Figure 1 for clarity of this initial explanation.

The HMD of Figure 1 completely (or at least substantially completely) obscures the user's view of the surrounding environment. All that the user can see is the pair of images displayed within the HMD.

The HMD has associated headphone audio transducers or earpieces 60 which fit into the user's left and right ears 70. The earpieces 60 replay an audio signal provided from an external source, which may be the same as the video signal source which provides the video signal for display to the user's eyes.

The combination of the fact that the user can see only what is displayed by the HMD and, subject to the limitations of the noise blocking or active cancellation properties of the earpieces and associated electronics, can hear only what is provided via the earpieces, mean that this HMD may be considered as a so-called "full immersion" HMD. Note however that in some embodiments the HMD is not a full immersion HMD, and may provide at least some facility for the user to see and/or hear the user's surroundings. This could be by providing some degree of transparency or partial transparency in the display arrangements, and/or by projecting a view of the outside (captured using a camera, for example a camera mounted on the HMD) via the HMD's displays, and/or by allowing the transmission of ambient sound past the earpieces and/or by providing a microphone to generate an input sound signal (for transmission to the earpieces) dependent upon the ambient sound.

A front-facing camera 122 may capture images to the front of the HMD, in use. A Bluetooth® antenna 124 may provide communication facilities or may simply be arranged as a directional antenna to allow a detection of the direction of a nearby Bluetooth transmitter.

In operation, a video signal is provided for display by the HMD. This could be provided by an external video signal source 80 such as a video games machine, a so-called break-out box (see below) or data processing apparatus (such as a personal computer), in which case the signals could be transmitted to the HMD by a wired or a wireless connection 82. Examples of suitable wireless connections include Bluetooth® connections. Audio signals for the earpieces can be carried by the same connection. Similarly, any control signals passed from the HMD to the video (audio) signal source may be carried by the same connection. Furthermore, a power supply 83 (including one or more bafteries and/or being connectable to a mains power outlet) may be linked by a cable 84 to the HMD. Note that the power supply 83 and the video signal source 80 may be separate units or may be embodied as the same physical unit. There may be separate cables for power and video (and indeed for audio) signal supply, or these may be combined for carriage on a single cable (for example, using separate conductors, as in a USB cable, or in a similar way to a "power over Ethernet" arrangement in which data is carried as a balanced signal and power as direct current, over the same collection of physical wires).

The video and/or audio signal may be carried by, for example, an optical fibre cable. In other embodiments, at least part of the functionality associated with generating image and/or audio signals for presentation to the user may be carried out by circuitry and/or processing forming part of the HMD itself. A power supply may be provided as part of the HMD itself.

Some embodiments of the invention are applicable to an HMD having at least one electrical and/or optical cable linking the HMD to another device, such as a power supply and/or a video (and/or audio) signal source. So, embodiments of the invention can include, for

example:

(a) an HMD having its own power supply (as part of the HMD arrangement) but a cabled connection to a video and/or audio signal source; (b) an HMD having a cabled connection to a power supply and to a video and/or audio signal source, embodied as a single physical cable or more than one physical cable; (c) an HMD having its own video and/or audio signal source (as part of the HMD arrangement) and a cabled connection to a power supply; or (d) an HMD having a wireless connection to a video and/or audio signal source and a cabled connection to a power supply.

If one or more cables are used, the physical position at which the cable 82 and/or 84 enters or joins the HMD is not particularly important from a technical point of view. Aesthetically, and to avoid the cable(s) brushing the user's face in operation, it would normally be the case that the cable(s) would enter or join the HMD at the side or back of the HMD (relative to the orientation of the user's head when worn in normal operation). Accordingly, the position of the cables 82, 84 relative to the HMD in Figure 1 should be treated merely as a schematic representation.

Accordingly, the arrangement of Figure 1 provides an example of a head-mountable display system comprising a frame to be mounted onto an observer's head, the frame defining one or two eye display positions which, in use, are positioned in front of a respective eye of the observer and a display element mounted with respect to each of the eye display positions, the display element providing a virtual image of a video display of a video signal from a video signal source to that eye of the observer.

Figure 1 shows just one example of an HMD. Other formats are possible: for example an HMD could use a frame more similar to that associated with conventional eyeglasses, namely a substantially horizontal leg extending back from the display portion to the top rear of the user's ear, possibly curling down behind the ear. In other (not full immersion) examples, the user's view of the external environment may not in fact be entirely obscured; the displayed images could be arranged so as to be superposed (from the users point of view) over the external environment. An example of such an arrangement will be described below with reference to Figure 4.

In the example of Figure 1, a separate respective display is provided for each of the user's eyes. A schematic plan view of how this is achieved is provided as Figure 2, which illustrates the positions 100 of the users eyes and the relative position 110 of the user's nose.

The display portion 50, in schematic form, comprises an exterior shield 120 to mask ambient light from the user's eyes and an internal shield 130 which prevents one eye from seeing the display intended for the other eye. The combination of the users face, the exterior shield 120 and the interior shield 130 form two compartments 140, one for each eye. In each of the compartments there is provided a display element 150 and one or more optical elements 160.

The way in which the display element and the optical element(s) cooperate to provide a display to the user will be described with reference to Figure 3.

Referring to Figure 3, the display element 150 generates a displayed image which is (in this example) refracted by the optical elements 160 (shown schematically as a convex lens but which could include compound lenses or other elements) so as to generate a virtual image 170 which appears to the user to be larger than and significantly further away than the real image generated by the display element 150. As an example, the virtual image may have an apparent image size (image diagonal) of more than 1 m and may be disposed at a distance of more than 1 m from the users eye (or from the frame of the HMD). In general terms, depending on the purpose of the HMD, it is desirable to have the virtual image disposed a significant distance from the user. For example, if the HMD is for viewing movies or the like, it is desirable that the user's eyes are relaxed during such viewing, which requires a distance (to the virtual image) of at least several metres. In Figure 3, solid lines (such as the line 180) are used to denote real optical rays, whereas broken lines (such as the line 190) are used to denote virtual rays.

An alternative arrangement is shown in Figure 4. This arrangement may be used where it is desired that the user's view of the external environment is not entirely obscured. However, it is also applicable to HMDs in which the users external view is wholly obscured. In the arrangement of Figure 4, the display element 150 and optical elements 200 cooperate to provide an image which is projected onto a mirror 210, which deflects the image towards the user's eye position 220. The user perceives a virtual image to be located at a position 230 which is in front of the user and at a suitable distance from the user.

In the case of an HMD in which the user's view of the external surroundings is entirely obscured, the mirror 210 can be a substantially 100% reflective mirror. The arrangement of Figure 4 then has the advantage that the display element and optical elements can be located closer to the centre of gravity of the user's head and to the side of the users eyes, which can produce a less bulky HMD for the user to wear. Alternatively, if the HMD is designed not to completely obscure the users view of the external environment, the mirror 210 can be made partially reflective so that the user sees the external environment, through the mirror 210, with the virtual image superposed over the real external environment.

In the case where separate respective displays are provided for each of the users eyes, it is possible to display stereoscopic images. An example of a pair of stereoscopic images for display to the left and right eyes is shown in Figure 5. The images exhibit a lateral displacement relative to one another, with the displacement of image features depending upon the (real or simulated) lateral separation of the cameras by which the images were captured, the angular convergence of the cameras and the (real or simulated) distance of each image feature from the camera position.

Note that the lateral displacements in Figure 5 could in fact be the other way round, which is to say that the left eye image as drawn could in fact be the right eye image, and the right eye image as drawn could in fact be the left eye image. This is because some stereoscopic displays tend to shift objects to the right in the right eye image and to the left in the left eye image, so as to simulate the idea that the user is looking through a stereoscopic window onto the scene beyond. However, some HMD5 use the arrangement shown in Figure 5 because this gives the impression to the user that the user is viewing the scene through a pair of binoculars. The choice between these two arrangements is at the discretion of the system designer.

In some situations, an HMD may be used simply to view movies and the like. In this case, there is no change required to the apparent viewpoint of the displayed images as the user turns the user's head, for example from side to side. In other uses, however, such as those associated with virtual reality (VR) or augmented reality (AR) systems, the user's viewpoint needs to track movements with respect to a real or virtual space in which the user is located.

Figure 6 schematically illustrates a user wearing an HMD connected to a Sony® PlayStation 3® games console 300 as an example of a base device. The games console 300 is connected to a mains power supply 310 and (optionally) to a main display screen (not shown).

A cable, acting as the cables 82, 84 discussed above (and so acting as both power supply and signal cables), links the HMD 20 to the games console 300 and is, for example, plugged into a USS socket 320 on the console 300. Note that in the present embodiments, a single physical cable is provided which fulfils the functions of the cables 82, 84. In Figure 6, the user is also shown holding a hand-held controller 330 which may be, for example, a Sony® Move® controller which communicates wirelessly with the games console 300 to control (or to contribute to the control of) game operations relating to a currently executed game program.

The video displays in the HMD 20 are arranged to display images generated by the games console 300, and the earpieces 60 in the HMD 20 are arranged to reproduce audio signals generated by the games console 300. Note that if a USB type cable is used, these signals will be in digital form when they reach the HMD 20, such that the HMD 20 comprises a digital to analogue converter (DAC) to convert at least the audio signals back into an analogue form for reproduction.

Images from the camera 122 mounted on the HMD 20 are passed back to the games console 300 via the cable 82, 84. Similarly, if motion or other sensors are provided at the HMD 20, signals from those sensors may be at least partially processed at the HMD 20 and/or may be at least partially processed at the games console 300. The use and processing of such signals will be described further below.

The USB connection from the games console 300 also provides power to the HMD 20, according to the USB standard.

Figure 7 schematically illustrates a similar arrangement in which the games console is connected (by a wired or wireless link) to a so-called "break out box" acting as a base or intermediate device 350, to which the HMD 20 is connected by a cabled link 82,84. The breakout box has various functions in this regard. One function is to provide a location, near to the user, for some user controls relating to the operation of the HMD, such as (for example) one or more of a power control, a brightness control, an input source selector, a volume control and the like. Another function is to provide a local power supply for the HMD (if one is needed according to the embodiment being discussed). Another function is to provide a local cable anchoring point. In this last function, it is not envisaged that the break-out box 350 is fixed to the ground or to a piece of furniture, but rather than having a very long trailing cable from the games console 300, the break-out box provides a locally weighted point so that the cable 82, 84 linking the HMD 20 to the break-out box will tend to move around the position of the break-out box. This can improve user safety and comfort by avoiding the use of very long trailing cables.

It will be appreciated that the localisation of processing in the various techniques described in this application can be varied without changing the overall effect, given that an HMD may form part of a set or cohort of interconnected devices (that is to say, interconnected for the purposes of data or signal transfer, but not necessarily connected by a physical cable).

So, processing which is described as taking place "at' one device, such as at the HMD, could be devolved to another device such as the games console (base device) or the break-out box.

Processing tasks can be shared amongst devices. Source signals, on which the processing is to take place, could be distributed to another device, or the processing results from the processing of those source signals could be sent to another device, as required. So any references to processing taking place at a particular device should be understood in this context.

Similarly, where an interaction between two devices is basically symmetrical, for example where a camera or sensor on one device detects a signal or feature of the other device, it will be understood that unless the context prohibits this, the two devices could be interchanged without any loss of functionality.

As mentioned above, in some uses of the HMD, such as those associated with virtual reality (VR) or augmented reality (AR) systems, the user's viewpoint needs to track movements with respect to a real or virtual space in which the user is located.

This tracking is carried out by detecting motion of the HMD and varying the apparent viewpoint of the displayed images so that the apparent viewpoint tracks the motion.

Figure 8 schematically illustrates the effect of a user head movement in a VR or AR system.

Referring to Figure 8, a virtual environment is represented by a (virtual) spherical shell 250 around a user. Because of the need to represent this arrangement on a two-dimensional paper drawing, the shell is represented by a part of a circle, at a distance from the user equivalent to the separation of the displayed virtual image from the user. A user is initially at a first position 260 and is directed towards a portion 270 of the virtual environment. It is this portion 270 which is represented in the images displayed on the display elements 150 of the user's HMD.

Consider the situation in which the user then moves his head to a new position and/or orientation 280. In order to maintain the correct sense of the virtual reality or augmented reality display, the displayed portion of the virtual environment also moves so that, at the end of the movement, a new portion 290 is displayed by the HMD.

So, in this arrangement, the apparent viewpoint within the virtual environment moves with the head movement. If the head rotates to the right side, for example, as shown in Figure 8, the apparent viewpoint also moves to the right from the user's point of view. If the situation is considered from the aspect of a displayed object, such as a displayed object 300, this will effectively move in the opposite direction to the head movement. So, if the head movement is to the right, the apparent viewpoint moves to the right but an object such as the displayed object 300 which is stationary in the virtual environment will move towards the left of the displayed image and eventually will disappear off the left-hand side of the displayed image, for the simple reason that the displayed portion of the virtual environment has moved to the right whereas the displayed object 300 has not moved in the virtual environment.

Figures 9a and 9b schematically illustrated HMD5 with motion sensing. The two drawings are in a similar format to that shown in Figure 2. That is to say, the drawings are schematic plan views of an HMD, in which the display element 150 and optical elements 160 are represented by a simple box shape. Many features of Figure 2 are not shown, for clarity of the diagrams. Both drawings show examples of HMD5 with a motion detector for detecting motion of the observer's head.

In Figure Ga, a forward-facing camera 322 is provided on the front of the HMD. This may be the same camera as the camera 122 discussed above, or may be an additional camera.

This does not necessarily provide images for display to the user (although it could do so in an augmented reality arrangement). Instead, its primary purpose in the present embodiments is to allow motion sensing. A technique for using images captured by the camera 322 for motion sensing will be described below in connection with Figure 10. In these arrangements, the motion detector comprises a camera mounted so as to move with the frame; and an image comparator operable to compare successive images captured by the camera so as to detect inter-image motion.

Figure 9b makes use of a hardware motion detector 332. This can be mounted anywhere within or on the HMD. Examples of suitable hardware motion detectors are piezoelectric accelerometers or optical fibre gyroscopes. It will of course be appreciated that both hardware motion detection and camera-based motion detection can be used in the same device, in which case one sensing arrangement could be used as a backup when the other one is unavailable, or one sensing arrangement (such as the camera) could provide data for changing the apparent viewpoint of the displayed images, whereas the other (such as an accelerometer) could provide data for image stabilisation.

Figure 10 schematically illustrates one example of motion detection using the camera 322 of Figure Ga.

The camera 322 is a video camera, capturing images at an image capture rate of, for example, 25 images per second. As each image is captured, it is passed to an image store 400 for storage and is also compared, by an image comparator 410, with a preceding image retrieved from the image store. The comparison uses known block matching techniques (so-called "optical flow" detection) to establish whether substantially the whole image has moved since the time at which the preceding image was captured. Localised motion might indicate moving objects within the field of view of the camera 322, but global motion of substantially the whole image would tend to indicate motion of the camera rather than of individual features in the captured scene, and in the present case because the camera is mounted on the HMD, motion of the camera corresponds to motion of the HMD and in turn to motion of the user's head.

The displacement between one image and the next, as detected by the image comparator 410, is converted to a signal indicative of motion by a motion detector 420. If required, the motion signal is converted by to a position signal by an integrator 430.

As mentioned above, as an alternative to, or in addition to, the detection of motion by detecting inter-image motion between images captured by a video camera associated with the HMD, the HMD can detect head motion using a mechanical or solid state detector 332 such as an accelerometer. This can in fact give a faster response in respect of the indication of motion, given that the response time of the video-based system is at best the reciprocal of the image capture rate. In some instances, therefore, the detector 332 can be better suited for use with higher frequency motion detection. However, in other instances, for example if a high image rate camera is used (such as a 200 Hz capture rate camera), a camera-based system may be more appropriate. In terms of Figure 10, the detector 332 could take the place of the camera 322, the image store 400 and the comparator 410, so as to provide an input directly to the motion detector 420. Or the detector 332 could take the place of the motion detector 420 as well, directly providing an output signal indicative of physical motion.

Other position or motion detecting techniques are of course possible. For example, a mechanical arrangement by which the HMD is linked by a moveable pantograph arm to a fixed point (for example, on a data processing device or on a piece of furniture) may be used, with position and orientation sensors detecting changes in the deflection of the pantograph arm. In other embodiments, a system of one or more transmitters and receivers, mounted on the HMD and on a fixed point, can be used to allow detection of the position and orientation of the HMD by triangulation techniques. For example, the HMD could carry one or more directional transmitters, and an array of receivers associated with known or fixed points could detect the relative signals from the one or more transmitters. Or the transmifters could be fixed and the receivers could be on the HMD. Examples of transmitters and receivers include infra-red transducers, ultrasonic transducers and radio frequency transducers. The radio frequency transducers could have a dual purpose, in that they could also form part of a radio frequency data link to and/or from the HMD, such as a Bluetooth® link.

Figure 11 schematically illustrates image processing carried out in response to a detected position or change in position of the HMD.

As mentioned above in connection with Figure 10, in some applications such as virtual reality and augmented reality arrangements, the apparent viewpoint of the video being displayed to the user of the HMD is changed in response to a change in actual position or orientation of the user's head.

With reference to Figure 11, this is achieved by a motion sensor 450 (such as the arrangement of Figure 10 and/or the motion detector 332 of Figure 9b) supplying data indicative of motion and/or current position to a required image position detector 460, which translates the actual position of the HMD into data defining the required image for display. An image generator 480 accesses image data stored in an image store 470 if required, and generates the required images from the appropriate viewpoint for display by the HMD. The external video signal source can provide the functionality of the image generator 480 and act as a controller to compensate for the lower frequency component of motion of the observer's head by changing the viewpoint of the displayed image so as to move the displayed image in the opposite direction to that of the detected motion so as to change the apparent viewpoint of the observer in the direction of the detected motion.

Figure 12 schematically illustrates an example peripheral device.

In this example, the peripheral device is a hand-held gaming controller 500 for use by the user in playing a computer game or the like. The controller 500 may have electronic sensors to detect its rotational and/or translational position, with that information being transmitted back to the HMD, the break-out box or the games console as telemetry data. The transmitted position can then be used as part of the controls of the game functionality. The controller 500 may also have user controls such as one or more buttons 510 and/or one or more joysticks 520. Again, user actions in respect of the buttons and/or joysticks may be transmitted by a wired or wireless connection to another device such as the HMD, a break-out box, a games console or the like.

The HMD can detect the presence and position (in a captured image) of the controller 500 by detecting passive markings or active illuminations provided on the controller 500, and/or by shape detection of at least features of the overall shape of the controller 500 (noting that, in use, some parts of the controller 500 will be obscured by the user's hands). The HMD can also detect the orientation of the controller 500 by the same techniques, but in other embodiments this detection would make use of telemetry data from the controller indicative of the current state of the controller's own orientation and/or position detectors.

Figure 13a schematically illustrates the device of Figure 12 as viewed by the camera of the HMD for example by using the forward facing camera 122 or 322. For clarity of the diagram, other image features (not least, the user's hands) have been omitted.

Because the forward-facing camera 122/322 of the HMD has a fixed spatial relationship to the displays of the HMD, it is possible for the system to (a) detect the current position of the controller 500 within an image 530, and then (b) to render a virtual object at that image position so that, to the user, the virtual object appears at a realistic image position. That is to say, the virtual object appears, in the displayed images, at substantially the same position that the real controller would appear if the user were not wearing the HMD.

Using the techniques described above, the HMD detects the image position of the controller 500, leading to a detected image position such as that shown in Figure 13b, where the centre of the detected image position of the controller 500 is indicated by a cross symbol 540 and the bounds of the image position are indicated by bounding bars 550. Note that these representations are simply for the purposes of this explanation; although an indication of the detected position may be stored in a memory associated with the HMD, the actual indications shown in Figure 13b are simply for the purposes of the present explanation.

Based on the detected position (as represented by the markings shown in Figure 13b), the HMD can then render a virtual object at that detected position, and having a rendered size dependent upon the image size (as indicated schematically by the bounding bars 550 in Figure 13b) of the controller 500. Examples of rendered objects are illustrated schematically in Figures 14a to 14c..

In Figure 14a, a virtual video "screen" 560 is rendered at the image position of the controller 500. To illustrate the correspondence of image positions, the positions of the cross marking 540 and the bounding bars 550 have been shown in Figure 14a, although of course these would not be rendered as part of the rendered video screen 560. The virtual video screen 560 provides a frame or a definition of an image area in which video content or the like is rendered for display to the user. A simple example might be that of displaying a movie for the user to watch, so that the user may set the position of the video screen 560 within the user's overall field of view by appropriately positioning the controller 500 in the real world. In another example, the video to be rendered on the virtual screen 560 may relate to an aspect of a videogame currently being played by the user; for example, the video could provide instructions or guidance, background information on a game character, information about the progress of another player, an overview or map of the game environment, another view of the player's environment (perhaps similar to a rear view mirror in a driving game) and so on. In embodiments of the invention, the user could choose to have the virtual video screen 560 rendered in place of the captured image of the controller 500 by making an appropriate selection using the user controls 510, 520 associated with the controller 500 and/or by moving the controller 500 to a particular position within the captured images. Similarly, the user could operate controls or move the controller to return to a view in which the virtual video screen 560 is not rendered.

In the example shown in Figure 14a, the virtual video screen 560 is exactly the same size as the detected size of the controller 500. Also, the virtual video screen 560 is centred around the detected centre 540 of the controller 500. Neither of these features is of course necessary. The virtual video screen could have a different size to that of the image size of the controller 500. In one example, the virtual video screen has a rendered size which is a predetermined multiple of the size of the controller 500 as detected in the captured image. An example of the predetermined multiple is 1.5. By having the virtual video screen 560 rendered so as to be bigger than the detected image size of the controller 500 (that is to say, by the predetermined multiple being greater than one), the entire controller 500 will be covered in the rendered image so as to avoid any parts of the controller 500 accidentally appearing around the edges of the rendered video screen 560.

Note that if the virtual video screen 560 has a particular aspect (width to height) ratio, which may be different to the aspect ratio of the area detected to be occupied by the controller 500 in the captured image, the selection of the size of the rendered virtual video screen 560 can be made based upon one dimension of the detected size of the controller. For example, the detected width (in the horizontal direction) of the controller 500 can then be scaled according to the predetermined multiple, which then determines the width of the virtual video screen 560.

The height of the virtual video screen 560 is derived from the width assigned to the virtual video screen 560 and the known aspect ratio required for the virtual video screen 560.

Similarly, although in the example shown in Figure 14a the virtual video screen is centred around the detected centre (shown by the cross marking 540) of the image position of the controller 500, the virtual video screen could be offset relative to the image position of the controller 500. For example, the virtual video screen 560 could be rendered so that its lower edge is aligned with the upper bound 551 of the detected position of the controller 500. In another example, the lower edge of the virtual video screen 560 could be aligned with a vertical position halfway between the centre and the upper bound of the detected position of the controller 500. This could allow the user to see the controller 500, or at least a part of it, in the rendered images as well as seeing the virtual video screen 560. Accordingly, there may be some overlap between the controller 500 and the virtual video screen 560 (with the virtual video screen 560 being rendered in place of the image of the controller 500 in the overlapping region) or the two may not overlap but the rendered size and position of the virtual video screen 560 still depends upon the detected size and position of the controller 500. In other embodiments, the virtual video screen 560 may be rendered lower, in the rendered image, than the detected position of the controller 500.

Similarly, the virtual video screen 560 may be rendered at a position which is horizontally centred around the left-to-right position of the controller 500, or may be offset to one side or the other.

A vertical and/or horizontal offset relative to the detected position of the controller 500 may be user selectable, for example, by using user controls such as a joystick control 520.

In embodiments of the invention, a constraint may be applied so that the whole of the virtual video screen is always rendered, even if the controller 500 approaches the edge of the captured image. In other words, as the controller 500 gets near to the edge of the captured image, the relationship between the detected position of the controller 500 and the rendered position of the virtual screen 560 may be changed. In one example, as soon as one edge of the virtual screen 560 reaches the edge of the rendered image, any further movement of the controller 500 in an outwards direction with respect to the rendered image does not result in a corresponding outward movement of the virtual screen 560. As soon as the controller 500 returns towards the centre of the image so that a normal mapping of the edition of the virtual screen 562. The position of the controller 500 would mean that the virtual screen 560 is rendered inside of the edge of the rendered image, the rendered position of the virtual screen 560 can return to tracking the detected position of the controller 500 in the normal way.

Figure 14b schematically illustrates a user control menu 570, which can be rendered at the position of the controller 500 using any of the techniques described, with reference to Figure 14a. The user control menu comprises a plurality of menu items 572, 574, 576... with user selection of one menu item being indicated by a movable bounding box 578. Once the user has moved the bounding box 578 to the required menu item, the user may operate a control button 510 to select the corresponding menu item 572. In another example, moving the bounding box 578 from one menu item to another may be achieved by changing the orientation of the controller 500, for example by rotating the controller 500 towards or away from the user.

The examples given in Figures 14a and 14b have related to rendered items which are represented in the plane of the rendered image. Some variations of this arrangement are possible.

In one example, bearing in mind that the HMD may have a stereoscopic display, the virtual screen 560 or the menu 570 may be rendered at a depth position, within the 3-D environment, represented by the stereoscopic display, which depends upon the detected distance between the HMD and the controller 500. The distance can be detected from the image size (in Figure 13a) of the controller 500, for example. In some examples, the depth position at which the virtual screen 560 or the menu 570 is rendered may correspond directly to the detected distance. In other examples, there may be a mapping between detected distance and rendered depth so as to exaggerate or reduce the effect of changes in the actual distance between the HMD and the controller 500.

In other examples, the virtual screen 560 or the menu 570 may be rendered so as to be partially transparent with respect to the captured image.

In other examples, the virtual screen 560 or the menu 570 may be rendered on a part-cylindrical or part-spherical basis rather than as a flat plain object within the 3-D environment provided by the stereoscopic HMD display.

In further examples, the virtual screen 560 or the menu 570 may be rendered so as to have an orientation relative to the viewer which depends upon the real orientation of the controller 500. As discussed above, the orientation of the controller 500 can be detected either optically or by using telemetry data transmitted by a wired or wireless connection from the controller 500 to the HMD. The rendered representation of the virtual screen 560 or the menu 570 can then be rotated (in either a 2-D or a 3-D representation depending on the capabilities of the HMD displays) so as to be tilted towards or away from the user around a vertical and/or a horizontal axis. Figure 14c schematically illustrates an example of rotation around a horizontal axis (shown in Figure 14c as an axis 580, but not displayed as part of the rendered image) such that the top of the virtual screen 560 or the menu 570 is tilted away from the viewer and the bottom of the virtual screen 560 or the menu 570 is tilted towards the viewer.

For example, the virtual item may be a virtual telephone such as, for example, a virtual smartphone. In some arrangements, the telephone could be first displayed either in response from a command from the user to indicate that the user wishes to make a telephone call, or in response to an incoming call associated with a user account to which the user is logged in, a telephone to which the HMD system is currently associated (for example, a mobile telephone to which the system is linked by a Bluetooth ® link) or to another type of incoming message such as a detection of an activation of a smoke alarm or a doorbell.

The system can be configured to connect an incoming telephone or other call to the user in response to the user lifting the peripheral and/or control device, for example by a detection, by the peripheral and/or control device (or by a camera associated with the HMD viewing the device) of a change in vertical position of (say) at least 5cm. The user can then interact with the call by means of earpieces associated with the HMD and a microphone (for example also associated with the HMD).

The virtual telephone can also receive and/or send textual messages such as virtual (or actual) SMS messages, either via the public telephone system or by a user-to-user communication within the virtual environment.

The system could render one of a set of at least two virtual items at the image position, the selection of a virtual item from the set being dependent upon one or both of: (a) a detected orientation of the peripheral and/or control device; and (b) a detected position of the peripheral and/or control device relative to the HMD. For example, the virtual smartphone could have two displays, one on each of a pair of opposed faces, with eth appropriate screen being displayed depending on the current rotational orientation of the peripheral. So, for example, the user could view the other screen by turning the peripheral over. These techniques apply to the various embodiments discussed here.

Instead, or in addition, the virtual item displayed at the peripheral position could comprise a virtual keyboard. The virtual keyboard could be operated, for example, by means of tracking the position of the user's fingers and/or thumbs. This can be done simply by recognizing the position of these digits in images captured by the HMD camera, but it can be assisted by the user wearing coloured and/or reflective finger covers (thimbles) to allow the position of the tip of each digit to be detected more easily and more accurately.

Figure 15 schematically illustrates part of the functionality of an HMD.

The HMD comprises a forward-facing camera 122/322 as discussed above, and this camera is, in the present arrangement, viewing a peripheral control device 600 (such as the controller 500) disposed in front of the user. An example of such a peripheral control device is a controller as discussed above, but many other such devices may be considered, such as a steering wheel, weapon, a bat or racquet, a gearstick, a handlebar, Sony® PlayStation ® Move TM controller, and the like.

Images captured by the camera 122/322 are supplied to a detector 610 and an image processor 620. These devices share the functionality of deriving detail from the image in the manner discussed above. In one example, the detector 610 is operable to detect the general location of the peripheral device (relative to the HMD for example) by shape matching and/or detecting markers or illuminations associated with the device, and the image processor 620 is operable to detect movements of the device in the captured images. The detector 610 may also receive telemetry data from the device 600 indicative of at least the orientation of the device 600.

The image processor 620 passes information to a renderer 630 which generates a virtual item (for example, a video screen 560 or a menu 570) for display to the user, at an image position dependent upon the detected position of the device 600.

Optionally, a controller 640 may send data to the device 600 in dependence upon the rendered image. For example, the device 600 may be instructed to vibrate or rumble in some way whenever the user moves the bounding box 578 to a new menu item. Or the device 600 could be instructed by the controller to provide some type of haptic feedback (such as a vibration or a rumble) in response to video content displayed on a virtual video screen 560.

The arrangements discussed above assume that the camera is provided as part of the HMD. Figure 16 schematically illustrates part of the functionality of a hand held peripheral device 700 which makes use of a camera 710 associated with the handheld peripheral device.

Note that the peripheral device may be a specific gaming device such as a steering wheel control or a hand-held game controller such as the Sony Six-axis ® controller, or may be, for example, a generic device such as a mobile telephone.

In operation, the camera 710 of the peripheral device captures images of the HMD, assuming the peripheral device is held by the user in front of the HMD, and either processes those images itself or (as shown in Figure 16) passes data relating to those images by telemetry (for example, wireless telemetry) to a processor 720 associated with the HMD. The processor 720 detects the position of the peripheral device 700 with respect to the HMD and passes data to a renderer 730 which renders a virtual item at the appropriate position according to the data received from the processor 720.

Note that the arrangement shown in Figure 16 can be used in order for the relative position of the HMD and the break-out box to be established, but in this instance, the camera 710 would be the HMD camera or a camera associated with the break-out box, and the presence in a captured image of the other of the HMD and the break-out box is detected.

Note that the field of view or direction of the images as captured by the forward facing camera 122/322 does not need to be the same as the field of view or direction of the images as displayed to the user. But there would be a relationship between the orientation and field of view of the camera and the orientation and field of view of the HMD displays so that a position in the images rendered for the HMD display can be selected so as to correspond to the detected real position of the controller.

In other embodiments, the camera (shown as 710 in Figure 16) could be separate to both the HMD and the peripheral and/or control device. For example, the camera could be associated with a games machine (such as the machine 300 described earlier) and arranged so as to capture images of both the HMD and the peripheral and/or control device so as to detect the relative position of the peripheral and/or control device with respect to the HMD.

Other position detection techniques could be used. In such cases, the detected position could form an input to the processor 720 of Figure 16 without necessarily requiring the camera 710 (though a camera could still be included in the system if desired). For example, the peripheral and/or control device could be mechanically connected to the HMD by a hinged arm such as a pantograph arrangement, so that the angle at one or more hinges of the pantograph could be detected and a relative position and/or orientation derived from the detected angle(s).

Alternatively a wireless system for detecting relative position could be used, such as that employed by the so-called Razer Hydra system (see http://en.wikipedia.org/wiki/Razer_Hydra).

At a basic level, any (relative) position detection arrangement could be used, and images would then be rendered at an image position (as seen by the wearer of the HMD) dependent on the detected position.

Accordingly, embodiments of the invention can provide a head mountable display (HMD) system comprising a camera operable to capture images of a peripheral and/or control device in use by a wearer of the HMD and to render a virtual item for display to the HMD wearer at an image position in dependence upon the detected position of the peripheral and/or control device.

The camera is an example of a more generic position detector operable to detect the position of the peripheral and/or control device, the position being (for example) a position relative to that of the HMD.

The virtual item may be a virtual video screen or a menu, for example. The peripheral and/or control device may provide user controls in respect of operations of the menu or control of the images rendered on the virtual screen.

The virtual item may be rendered at an image position dependent upon, but not necessarily centred around, the detected position of the peripheral and/or control device.

The virtual item may be rendered in 3-D space so as to have a depth dependent upon the distance from the peripheral and/or control device. It may be rendered in 2-D or 3-D space so as to appear flat, curved (for example, part-spherical or part-cylindrical), and may have an orientation dependent upon the detected orientation of the peripheral and/or control device.

The HMD could be displaying computer game material, for example. The HMD can be associated with one or more other devices such as a games console and/or a break-out box.

The detection of the device and/or of the occlusion could make use of the detection of markings and/or illumination on the device.

Another device can use a similar technique to detect the relative position of the HMD.

Multiple devices can detect their relative positions, whether with or without a camera. The other devices can be smartphones (including OS ® or Android ® smartphones, for example) or controllers such as the Move or Sixaxis controller.

Features such as haptic feedback can be applied to a peripheral in dependence upon the rendered virtual item or content associated with the rendered virtual item.

Although a camera could be mounted to the HMD, it could instead be mounted to the peripheral and/or control device, or could be separate to both the HMD and the peripheral andlor control device. Similarly, the position detector could be implemented at the HMD, at the peripheral and/or control device, or separately. In a camera based system, more than one camera may be employed -for example, an array or set of cameras.

Embodiments of the invention also provide an arrangement of an HMD, one or more peripheral or control devices, and optionally a base device such as a games console or break-out box.

Embodiments of the invention can also provide a method of operating a head mountable display (HMD) comprising detecting the position of a peripheral and/or control device in use by a wearer of the HMD and rendering a virtual item for display to the HMD wearer at an image position in dependence upon the detected position of the peripheral and/or control device.

It will be appreciated that embodiments of the present invention may be implemented in hardware, programmable hardware, software-controlled data processing arrangements or combinations of these. It will also be appreciated that computer software or firmware used in such embodiments, and providing media for providing such software or firmware (such as storage media, for example a machine-readable non-transitory storage medium such as a magnetic or optical disc or a flash memory) are considered to represent embodiments of the present invention.

Claims

CLAIMS1. A head mountable display (HMD) system comprising a position detector operable to detect the position of a peripheral and/or control device in use by a wearer of the HMD and to render a virtual item for display to the HMD wearer at an image position in dependence upon the detected position of the peripheral and/or control device.
2. An HMD system according to claim 1, in which the virtual item is a virtual video screen or a menu.
3. An HMD system according to claim 2, in which the peripheral and/or control device is operable to provide user controls in respect of operations of the menu or control of the images rendered on the virtual screen.
4. An HMD system according to any one of claims 1 to 3, in which the virtual item is rendered at an image position dependent upon the detected position of the peripheral and/or control device.
5. An HMD system according to claim 4, in which the virtual item is rendered at an image position centred upon the detected position of the peripheral and/or control device.
6. An HMD system according to any one of the preceding claims, in which the virtual item is rendered in 3-D space so as to have an apparent depth dependent upon the distance from the peripheral andlor control device.
7. An HMD system according to any one of the preceding claims, in which the virtual item is rendered in 2-D or 3-D space so as to appear flat.
8. An HMD system according to any one of claims 1 to 6, in which the virtual item is rendered in 2-D or 3-D space so as to appear curved.
9. An HMD system according to claim 8, in which the virtual item is rendered in 2-D or 3-D space so as to appear part-spherical or part-cylindrical.
10. An HMD system according to any one of the preceding claims, in which the position detector is operable to detect the orientation of the peripheral and/or control device, and in which the virtual item is rendered in 2-0 or 3-0 space so as to have an orientation dependent upon the detected orientation of the peripheral and/or control device.
11. An HMD system according to any one of the preceding claims, in which the HMD is operable to display computer game material.
12. An HMD system according to any one of the preceding claims, in which the position detector comprises a camera operable to capture images of the peripheral and/or control device.
13. An HMD system according to claim 12, in which the camera is mounted to the HMD.
14. An HMD system according to any one of the preceding claims, in which the virtual item is a virtual telephone.
15. An HMD system according to claim 14, the system being configured to connect an incoming telephone call to the user in response to the user lifting the peripheral and/or control device.
16. An HMD system according to any one of the preceding claims, the position detector being operable to render one of a set of at least two virtual items at the image position, the selection of a virtual item from the set being dependent upon one or both of: (a) a detected orientation of the peripheral and/or control device; and (b) a detected position of the peripheral and/or control device relative to the HMD.
17. An HMD system according to any one of the preceding claims, in which the virtual item comprises a virtual keyboard.
18. An HMD arrangement comprising an HMD system according to any one of the preceding claims and a peripheral and/or control device, the device having markings and/or illumination which are detectable by the position detector.
19. An arrangement according to claim 18, in which haptic feedback is applied to the peripheral and/or control device in dependence upon the rendered virtual item or content associated with the rendered virtual item.
20. A method of operating a head mountable display (HMD) comprising detecting the position of a peripheral and/or control device in use by a wearer of the HMD and rendering a virtual item for display to the HMD wearer at an image position in dependence upon the detected position of the peripheral and/or control device.
21. Computer software which, when executed by a computer, causes the computer to carry out the method of claim 20.
22. A non-transitory machine-readable storage medium which stores computer software according to claim 21.