WO2018096315A1

WO2018096315A1 - Virtual reality

Info

Publication number: WO2018096315A1
Application number: PCT/GB2017/053372
Authority: WO
Inventors: Martin SHENTON; Hogarth Andall
Original assignee: Sony Interactive Entertainment Europe Limited
Priority date: 2016-11-22
Filing date: 2017-11-09
Publication date: 2018-05-31
Also published as: GB201619706D0; GB2556114B; GB2556114A

Abstract

A virtual reality apparatus comprises an image generator to generate virtual environment images representing a virtual environment, at least some being for display to a user by a head mountable display to be worn by that user; a camera to capture one or more images; and an image combiner to combine one or more of the captured images with one or more of the virtual environment images.

Description

VIRTUAL REALITY

BACKGROUND

Field of the Disclosure

This disclosure relates to virtual reality systems and methods.

Description of the Prior Art

The "background" description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.

A head-mountable display (HMD) is one example of a head-mountable apparatus for use in a virtual reality system in which an HMD wearer views a virtual environment. 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 5m.

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

The foregoing paragraphs have been provided by way of general introduction, and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

Various aspects and features of the present disclosure 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.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

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 HMDs with motion sensing;

Figure 10 schematically illustrates a position sensor based on optical flow detection;

Figure 1 1 schematically illustrates image processing carried out in response to a detected position or change in position of an HMD;

Figures 12 and 13 schematically illustrate combined images;

Figure 14 schematically illustrates an apparatus;

Figure 15 is a schematic flowchart illustrating the operation of a background removal module;

Figures 16 and 17 are schematic flowcharts illustrating methods; Figure 18 schematically illustrates a virtual camera; and

Figures 19 to 22 are schematic flowcharts illustrating methods.

DESCRIPTION OF THE EMBODIMENTS

Referring now to Figure 1 , a user 10 is wearing an HMD 20 (as an example of a generic head-mountable apparatus or virtual reality apparatus). 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. A boom microphone 75 is mounted on the HMD so as to extend towards the user's mouth.

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 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 60 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 batteries 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 disclosure 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 disclosure 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 user's 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 user's eyes and the relative position 1 10 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 user's 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 user's 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 user's 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 user's eyes, which can produce a less bulky HMD for the user to wear. Alternatively, if the HMD is designed not to completely obscure the user's 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 user's 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 HMDs 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 an example virtual reality system and in particular shows 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 USB 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 pair of hand-held controller 330s which may be, for example, Sony® Move® controllers which communicate 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 6 also shows a separate display 305 such as a television or other openly viewable display (by which it is meant that viewers other than the HMD wearer may see images displayed by the display 305) and a camera 315, which may be (for example) directed towards the user (such as the HMD wearer) during operation of the apparatus. An example of a suitable camera is the PlayStation Eye camera, although more generally a generic "webcam", connected to the console 300 by a wired (such as a USB) or wireless (such as WiFi or Bluetooth) connection.

The display 305 may be arranged (under the control of the games console) to provide the function of a so-called "social screen". It is noted that playing a computer game using an HMD can be very engaging for the wearer of the HMD but less so for other people in the vicinity (particularly if they are not themselves also wearing HMDs). To provide an improved

experience for a group of users, where the number of HMDs in operation is fewer than the number of users, images can be displayed on a social screen. The images displayed on the social screen may be substantially similar to those displayed to the user wearing the HMD, so that viewers of the social screen see the virtual environment (or a subset, version or

representation of it) as seen by the HMD wearer. In other examples, the social screen could display other material such as information relating to the HMD wearer's current progress through the ongoing computer game. For example, the HMD wearer could see the game environment from a first person viewpoint whereas the social screen could provide a third person view of activities and movement of the HMD wearer's avatar, or an overview of a larger portion of the virtual environment. In these examples, an image generator (for example, a part of the functionality of the games console) is configured to generate some of the virtual environment images for display by a display separate to the head mountable display.

Figure 7 schematically illustrates a similar arrangement (another example of a virtual reality system) 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. This provides an example of a virtual display screen (VDS). 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. It can be seen from the drawing that the VDS subsists in three dimensional space (in a virtual sense) around the position in space of the HMD wearer, such that the HMD wearer sees a current portion of VDS according to the HMD orientation.

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 HMDs 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 HMDs with a motion detector for detecting motion of the observer's head.

In Figure 9a, 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 9a.

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 transmitters 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 1 1 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 1 1 , 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.

Example embodiments relate to so-called mixed reality, in which real images and virtually generated images are combined.

Figures 12 and 13 schematically illustrate examples of such combined images.

In Figure 12, a captured image 1200 of a user wearing an HMD has been superposed over a virtual environment image 1210 representing an example virtual environment. In Figure 13, an image 1300 (of a user not wearing an HMD, or of a user wearing an HMD in which the HMD has been replaced, for example by image processing to be discussed below, with image material representing the user's face) captured by a camera has been superposed over a virtual environment image 1310. Techniques by which the images are combined will be discussed below.

Figure 14 schematically illustrates an apparatus comprising a game engine 1400, for example implemented by the games console discussed above. The game engine provides images to a social screen 1410 and to an HMD 1420 which may be worn by a user. User operable controls 1430 are provided, an example being one or more Sony Move controllers as discussed above. The user operable controls provide examples of one or more user controls, the image generator being responsive to operation of the user controls by the user to vary a viewpoint used to generate at least some of the virtual environment images.

A camera 1440, represented in Figures 6 and 7 as the camera 315, is provided and, in use, may be directed towards the user wearing the HMD 1420.

Two other aspects of the logic implemented by the games console are also illustrated, these being a background removal module 1450 and an image combiner 1460.

Figure 14 therefore provides an example of a virtual reality apparatus comprising: an image generator (1400) to generate virtual environment images representing a virtual environment, at least some being for display to a user by a head mountable display (1420) to be worn by that user; a camera (1440) to capture one or more images; and an image combiner (1460) to combine one or more of the captured images with one or more of the virtual environment images.

Techniques by which combined images may be generated will be discussed below. First, however, Figure 15 is a schematic flowchart illustrating the operation of the background removal module 1450.

At a high level, the background removal module 1450 carries out the following steps. At a step 1500, the background removal module detects images received from the camera 1440. At a step 1510, the background removal module detects and stores image data relating to a background region, for example in an image data store 1455 (Figure 14). At a step 1520 the background removal module subtracts the stored background from the detected images.

Techniques by which the background removal module can operate to remove

background image material from the captured images can vary according to the type of camera used, for example. In some examples, the camera 1440 is a so-called depth camera. An example is a stereoscopic camera, but other types of cameras using structured infrared light (for example, a projected grid of infrared light from which depth information can be acquired using an infrared sensor) are also capable of detecting the depth parameter of image material in a captured image. The step 1510 can be carried out by the background removal module detecting background image material as image material having a greater image depth than other (foreground) image material in the captured images. So, in such examples, the

foreground is taken to be image material or item (for example, of at least a threshold size, in pixels) which is closest to the camera. In other examples, the user could indicate an image region in which the foreground material is the closest of any material within that image region to the camera. In other examples, the step 1510 can be implemented by the background removal module detecting background image material as that image material which is static with respect to a plurality of captured images.

Figures 16 and 17are schematic flowcharts illustrating methods. In the present examples, Figure 16 schematically represents an example process which will lead towards the type of combined image shown in schematically in Figure 12. Figure 17 represents an example process which might lead to the type of image shown in Figure 13.

Figure 16 schematically illustrates a method relating to the generation of an image of the type shown in Figure 12 as described above.

At a step 1600, the user, wearing an HMD, views a scene using the HMD relating to a virtual environment.

At a step 1610, the user, while wearing the HMD, positions himself in front of the camera 1440 (Figure 14) such that the camera 1440 can capture an image of the user wearing the HMD.

At a step 1620, the user moves (for example translates) and/or rotates the position and/or orientation of the camera 1440, and/or moves, translates, rotates or otherwise adjusts the position of the current view of the virtual environment (discussed below with reference to Figure 18). Other adjustments which may be included within this operation include zooming the physical camera 1440 and/or the in-game virtual camera defining a viewpoint within the virtual environment. Adjustments relating to the virtual view can be made using the controls 1430, for example. Adjustments to the view of the physical camera 1440 can be made by physical movements (directly, or using motor drives, for example) of the camera 1440, and/or by physical movement of the user relative to the camera 1440.

The scene as viewed by the user at the step 1600 may be, for example, a third person view of the user or, for the purposes of these techniques, may be any desired view of the virtual environment.

At a step 1630, the user, by operating one or more controls 1430, causes the camera 1440 to capture either one or more still photographs or a portion of video material including images of the user wearing the HMD.

Example embodiments can superpose video content captured by the camera 1440 onto video content relating to the virtual environment; or still content captured by the camera 1440 onto video content relating to the virtual environment; or video content captured by the camera 1440 onto still content relating to the virtual environment; or still content captured by the camera 1440 onto still content relating to the virtual environment. Audio content can be muted; or audio content relating to the physical environment (for example, captured by a separate microphone, by a microphone associated with the HMD, by a microphone associated with the camera 1440, or more than one of these) can be associated with the resulting image content; or audio content from the virtual environment can be associated with the resulting image content; or a mix (for example, under user control) of audio content from the virtual environment and audio content from the physical environment. Audio content can be provided even if the resulting image content is a still image.

At a step 1640, the virtual environment images and the captured images are combined by the image combiner 1460. This can involve first removing background image content (that is to say image content other than captured images of the user wearing the HMD) by the background removal module 1450. So, the images of the user wearing the HMD are

superposed on the virtual environment images.

At this stage, the user can may further adjustments to the position of the images of the user with relation to the virtual environment (similar to the step 1620). In other examples, the step 1620 can include the display of a preview version of an image which would be captured by the camera at the step 1630 so that the user can make appropriate position and/or orientation adjustments.

The images and/or video material produced by the step 1640 may then be shared by the user, for example by storing the images and/or video material to system memory or a nonvolatile store forming part of the games console, and/or by transmitting the images and/or video material to other users over a network connection, by a social media interaction or the like.

Figure 17 schematically illustrates a similar method, but in this example the user (who might normally play the game in the virtual environment by wearing the HMD) uses the camera 1440 to capture images of the user not wearing the HMD. These images can then be combined with virtual environment images as discussed above.

Referring to Figure 17, at a step 1700 the user removes the HMD from the user's head and, at a step 1710, the user positions himself in front of the camera 1440.

While the user is not wearing the HMD, the user can in fact view the captured images or a preview version of those images on the social screen 1410 so as to carry out a step 1730 which involves adjusting the physical camera and/or virtual camera in a similar manner to the adjustments described above with reference to the step 1620. Once the user is satisfied with the current position and orientations, the user operates one or more of the controls 1430 to cause the camera to capture one or more still photographs or a portion of video content at a step 1740. As discussed above, the captured photographs and/or video content are combined with the virtual environment images at a step 1750 and the resulting photographs and/or video material can be shared as discussed above at a step 1760.

Note that the flow chart of Figure 17 can be carried out in multiple stages, which is to say, by way of example, the user could capture images of the user not wearing the HMD (the steps 1700 to 1740) separate to the user's interaction with the virtual environment, so that the step 1750 can be implemented later when the user is at an appropriate location within the virtual environment.

Figure 18 schematically illustrates a virtual camera or viewpoint within a virtual environment.

In Figure 18 the virtual environment is schematically represented by a portion of a map 1800 of the virtual environment, such that the virtual camera occupies a position 1810 which may be translated in any direction 1820 either under game control or user control. Similarly, the user occupies a position within the virtual environment during game play. If a first person view is being provided to the user, then the virtual camera position 1810 can be identical to the position of the user within the virtual environment during game play. In such examples, the virtual environment includes an avatar representation of the user positioned within the virtual environment so that the user's viewpoint of the virtual environment substantially corresponds to the viewpoint of the avatar corresponding to that user.

The camera viewpoint is also adjustable (while remaining at the location 1810 within the virtual environment) up and down 1830 and rotationally in a panning motion 1840. Again, this can be under user control either by the user changing his own viewpoint during game play or according to the steps 1620, 1730 discussed above to provide a virtual environment image for combination with a captured image.

Figures 19-21 schematically illustrate further operations which may be carried out

(individually or in combination) in association with the steps 1640, 1750 discussed above. In these examples, an image processor is configured to detect one or more portions of a captured image and to replace the detected one or more portions with other image material. The one or more portions may comprise an image of the head mountable display; or an image of the user's head.

Figure 19 schematically illustrates a technique for processing images captured of a user wearing an HMD so as to reintroduce the user's eyes and facial features which would otherwise be obscured by the HMD.

At a step 1900, the image combiner 1460, operating as an image processor, detects that part of the captured image or images relating to the HMD itself. This can be carried out, for example, by detecting fiduciary or other distinguishing markers on the front face of the HMD. For example, markers or lights may be provided in any event to allow for positional tracking of the HMD by a camera associated with the games console, and these can be used to identify the location within the image of the HMD. Shape mapping techniques can then be used to detect the outline of the HMD around those fiduciary markers.

At a step 1910, the image combiner 1460 generates a portion of an image containing at least substitute eyes, and in other examples a substitute facial region covering the region which would be obscured by the HMD when worn.

At a step 1920, the image combiner 1460 combines the substitute image generated at the step 1910 with the captured image. This can be carried out, for example, so as to remove the image portion relating to the HMD and completely substitute it with facial features, or in other examples the combination can be such so that the HMD appears to be partially transparent so that the eyes and facial features may be seen through it.

The substitute image produced at the step 1910 can be obtained, for example, from images of the user captured while the user was not wearing the HMD, for example as part of a user profile or a set up stage before game play starts.

Figure 20 schematically illustrates another example of processing which can be carried out by the image combiner 1460.

At a step 2000, the image combiner 1460 detects that part of the captured image relating to the user's head. This can be achieved by using known head or face detection algorithms, and/or by detecting one or more markers (for example associated with the HMD - if the user is wearing it at the time - and/or an item of headwear the user is wearing).

Noting that in a typical application of these techniques, it may be the case that the captured images of the user do not include the whole of the user's body. This simply relates to practical restrictions on the positioning of the camera 1440 relative to the user in a normal room environment. However, the user may wish to appear as a full body in the combined images. To achieve this, at a step 2010 the image combiner 1460 generates an avatar body for the user (for example, selectable in terms of attributes, pose and the like by the user operating the user controls 1430), and at a step 2020 combines the captured image of the user's head with the avatar body to produce a user with a complete body for combination with the virtual

environment images.

Another alternative is shown schematically in Figure 21 in which the image processor is configured to detect the user's head and to append it to an image of an avatar body. At a step 2100, the image combiner 1460 detects that part of the captured image relating to the user's head and, at a step 21 10 generates a substitute (for example, avatar) head which, at a step 2120, is inserted in place of the captured image of the user's head.

In any of these examples, the image processor may be configured to select or generate the other image material in response to a user profile associated with the user.

Figure 22 is a schematic flowchart illustrating a method comprising: generating (at a step 2200) virtual environment images representing a virtual environment, at least some being for display to a user by a head mountable display to be worn by that user;

capturing (at a step 2210) one or more images; and

combining (at a step 2220) one or more of the captured images with one or more of the virtual environment images.

It will be apparent that numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practised otherwise than as specifically described herein.

Claims

1 . A virtual reality apparatus comprising:

an image generator to generate virtual environment images representing a virtual environment, at least some being for display to a user by a head mountable display to be worn by that user;

a camera to capture one or more images; and

an image combiner to combine one or more of the captured images with one or more of the virtual environment images.

2. Apparatus according to claim 1 , the virtual environment including an avatar

representation of the user positioned within the virtual environment so that the user's viewpoint of the virtual environment substantially corresponds to the viewpoint of the avatar corresponding to that user.

3. Apparatus according to claim 2, in which the image generator is configured to generate some of the virtual environment images for display by a display separate to the head mountable display.

4. Apparatus according to any one of the preceding claims, comprising one or more user controls, the image generator being responsive to operation of the user controls by the user to vary a viewpoint used to generate at least some of the virtual environment images.

5. Apparatus according to any one of the preceding claims, comprising a background removal module to remove background image material from the captured images.

6. Apparatus according to claim 5, in which:

the camera is a depth camera; and

the background removal module is configured to detect background image material as image material having a greater image depth than other foreground image material in the captured images.

7. Apparatus according to claim 5, in which the background removal module is configured to detect background image material as image material which is static with respect to a plurality of captured images.

8. Apparatus according to any one of the preceding claims, comprising an image processor to detect one or more portions of a captured image and to replace the detected one or more portions with other image material.

9. Apparatus according to claim 8, in which the one or more portions comprise:

an image of the head mountable display; or

an image of the user's head.

10. Apparatus according to claim 8 or claim 9, in which the image processor is configured to detect the user's head and to append it to an image of an avatar body.

1 1 . Apparatus according to any one of claims 8 to 10, in which the image processor is configured to select or generate the other image material in response to a user profile associated with the user.

12. Apparatus according to any one of the preceding claims, comprising a head mountable display.

13. A method comprising:

generating virtual environment images representing a virtual environment, at least some being for display to a user by a head mountable display to be worn by that user;

capturing one or more images; and

combining one or more of the captured images with one or more of the virtual environment images.

14. Computer software which, when executed by a computer, causes the computer to execute the method of claim 13.

15. A non-transitory, machine-readable storage medium which stores computer software according to claim 14.