Generic conditional trigger in virtual environments

Abstract

Some embodiments of an example method may include: obtaining scene description data for a three- dimensional (3D) scene, wherein the scene description data includes behavior information including: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition includes a conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

Description

GENERIC CONDITIONAL TRIGGER IN VIRTUAL ENVIRONMENTSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims benefit of European Patent Application No. EP23306182, entitled “GENERIC CONDITIONAL TRIGGER IN VIRTUAL ENVIRONMENTS” and filed July 11 , 2023, which is hereby incorporated by reference in its entirety.BACKGROUND

[0002] Extended reality (XR) is a technology enabling interactive experiences where the real-world environment and / or a video content is enhanced by virtual content, which can be defined across multiple sensory modalities, including visual, auditory, haptic, etc. During runtime of the application, the virtual content (3D content or audio / video file for example) is rendered in real-time in a way which is consistent with the user context (environment, point of view, device, etc.). Scene graphs (such as the one proposed by Khronos / gITF and its extensions defined in MPEG Scene Description format or Apple / USDZ for instance) are a possible way to represent the content to be rendered. They combine a declarative description of the scene structure linking real-environment objects and virtual objects on one hand, and binary representations of the virtual content on the other hand.SUMMARY

[0003] Embodiments described herein include methods that are used in video encoding and decoding (collectively “coding”).

[0004] An example method in accordance with some embodiments may include: obtaining scene description data for a three-dimensional (3D) scene, wherein the scene description data includes behavior information including: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition includes a conditional trigger; and wherein the trigger information includes a path to an attribute, wherein the attribute is used with the conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

[0005] For some embodiments of the example method, the at least one trigger condition includes a test on the attribute.

[0006] An example apparatus in accordance with some embodiments may include: a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform the method of any one of the claims listed above.

[0007] An example method in accordance with some embodiments may include: obtaining scene description data for a three-dimensional (3D) scene, wherein the scene description data includes behavior information, which may include: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition may include a conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

[0008] For some embodiments of the example method, the at least one conditional trigger may include a path to a storage location, and the trigger information describing the at least one trigger condition is stored at the storage location.

[0009] Some embodiments of the example method may further include updating the trigger information at runtime.

[0010] Some embodiments of the example method may further include updating the trigger information prior to runtime.

[0011] Some embodiments of the example method may further include updating the conditional trigger at runtime.

[0012] Some embodiments of the example method may further include updating the conditional trigger prior to runtime.

[0013] For some embodiments of the example method, the trigger information may include one or more parameters, and the at least one trigger condition may be based on at least one of the one or more parameters.

[0014] For some embodiments of the example method, at least one of the one or more parameters may include a value field and a comparator field.

[0015] For some embodiments of the example method, the trigger information further includes node information indicating one or more nodes, and the method further includes: searching a memory structurecorresponding to the one or more nodes for a field matching the value field; and updating the conditional trigger based on the matching field.

[0016] For some embodiments of the example method, the trigger information further includes a descriptor field, and the method further includes using the descriptor field with the one or more parameters to determine the at least one trigger condition.

[0017] Some embodiments of the example method may further include: detecting a second condition; and responsive to detecting the second condition, updating the trigger information.

[0018] For some embodiments of the example method, the trigger information may further include at least one metadata field.

[0019] For some embodiments of the example method, the at least one trigger condition is based on the at least one metadata field.

[0020] For some embodiments of the example method, the conditional trigger may include two or more conditions.

[0021] For some embodiments of the example method, the at least one conditional trigger includes a path to a parameter to be compared, and the at least one trigger condition includes the parameter to be compared.

[0022] For some embodiments of the example method, the at least one trigger condition includes a test on the attribute.

[0023] An example apparatus in accordance with some embodiments may include: a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform any one of the methods listed above.

[0024] Another example method in accordance with some embodiments may include handling a conditional trigger related to a three-dimensional (3D) scene, wherein the conditional trigger may include a mechanism for updating one or more trigger conditions related to the conditional trigger.

[0025] An example apparatus in accordance with some embodiments may include: a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform the method listed above.

[0026] A further example method in accordance with some embodiments may include: obtaining scene description data for a three-dimensional (3D) scene, wherein the scene description data includes behavior information including: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger conditionincludes a conditional trigger; and wherein the trigger information includes a path to an attribute, wherein the attribute is used with the conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

[0027] For some embodiments of the further example method, the at least one trigger condition includes a test on the attribute.

[0028] A further example apparatus in accordance with some embodiments may include a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform any one of the methods listed above.

[0029] In additional embodiments, encoder and decoder apparatus are provided to perform the methods described herein. An encoder or decoder apparatus may include a processor configured to perform the methods described herein. The apparatus may include a computer-readable medium (e.g. a non-transitory medium) storing instructions for performing the methods described herein. In some embodiments, a computer-readable medium (e.g. a non-transitory medium) stores a video encoded using any of the methods described herein.

[0030] One or more of the present embodiments also provide a computer readable storage medium having stored thereon instructions for performing bi-directional optical flow, encoding or decoding video data according to any of the methods described above. The present embodiments also provide a computer readable storage medium having stored thereon a bitstream generated according to the methods described above. The present embodiments also provide a method and apparatus for transmitting the bitstream generated according to the methods described above. The present embodiments also provide a computer program product including instructions for performing any of the methods described.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 A is a schematic side view illustrating an example waveguide display that may be used with extended reality (XR) applications according to some embodiments.

[0032] FIG. 1 B is a schematic side view illustrating an example alternative display type that may be used with extended reality applications according to some embodiments.

[0033] FIG. 1 C is a schematic side view illustrating an example alternative display type that may be used with extended reality applications according to some embodiments.

[0034] FIG. 1 D is a system diagram illustrating an example set of interfaces for a system according to some embodiments.

[0035] FIG. 1 E is a system diagram illustrating an example set of interfaces for a scene description (stored as an item in gITF.json), three video tracks, an audio track, and a JSON patch update track in an ISOBMFF file according to some embodiments.

[0036] FIG. 2 is a system diagram illustrating an example set of interfaces for an MPEG-I node hierarchy supporting elements of scene interactivity according to some embodiments.

[0037] FIG. 3 is a block diagram showing an example of logical relationships between trigger information (describing triggers 1 through n), action information (describing actions 1 through m), and behavior information (describing relationships between the triggers and actions) in which triggers and actions may refer to one or more nodes in a scene description, such as a hierarchical scene graph, according to some embodiments.

[0038] FIG. 4 is a schematic plan view illustrating example relationships of extended reality scene description objects according to some embodiments.

[0039] FIG. 5 is a flowchart illustrating example pre-processing of a conditional trigger according to some embodiments.

[0040] FIG. 6 is a flowchart illustrating example pre-processing of a conditional trigger according to some embodiments.

[0041] FIG. 7 is a flowchart illustrating example pre-processing of a conditional trigger according to some embodiments.

[0042] FIGs. 8A-8B form a code listing illustrating an example code structure for base scene elements according to some embodiments.

[0043] FIG. 9 is a code listing illustrating an example code structure for a conditional trigger metadata according to some embodiments.

[0044] FIGs. 10A-10B form a code listing illustrating an example code structure for a conditional trigger according to some embodiments.

[0045] FIG. 1 1 is a flowchart illustrating an example process for processing a conditional trigger according to some embodiments.

[0046] The entities, connections, arrangements, and the like that are depicted in— and described in connection with— the various figures are presented by way of example and not by way of limitation. As such, any and all statements or other indications as to what a particular figure “depicts,” what a particular element or entity in a particular figure “is” or “has,” and any and all similar statements— that may in isolation and outof context be read as absolute and therefore limiting— may only properly be read as being constructively preceded by a clause such as “In at least one embodiment, ....” For brevity and clarity of presentation, this implied leading clause is not repeated ad nauseum in the detailed description.DETAILED DESCRIPTION

[0047] FIG. 1 A is a schematic side view illustrating an example waveguide display that may be used with extended reality (XR) applications according to some embodiments. An image is projected by an image generator 102. The image generator 102 may use one or more of various techniques for projecting an image. For example, the image generator 102 may be a laser beam scanning (LBS) projector, a liquid crystal display (LCD), a light-emitting diode (LED) display (including an organic LED (OLED) or micro LED ( LED) display), a digital light processor (DLP), a liquid crystal on silicon (LCoS) display, or other type of image generator or light engine.

[0048] Light representing an image 112 generated by the image generator 102 is coupled into a waveguide 104 by a diffractive in-coupler 106. The in-coupler 106 diffracts the light representing the image 112 into one or more diffractive orders. For example, light ray 108, which is one of the light rays representing a portion of the bottom of the image, is diffracted by the in-coupler 106, and one of the diffracted orders 110 (e.g. the second order) is at an angle that is capable of being propagated through the waveguide 104 by total internal reflection. The image generator 102 displays images as directed by a control module 124, which operates to render image data, video data, point cloud data, or other displayable data.

[0049] At least a portion of the light 110 that has been coupled into the waveguide 104 by the diffractive in-coupler 106 is coupled out of the waveguide by a diffractive out-coupler 114. At least some of the light coupled out of the waveguide 104 replicates the incident angle of light coupled into the waveguide. For example, in the illustration, out-coupled light rays 116a, 116b, and 116c replicate the angle of the in-coupled light ray 108. Because light exiting the out-coupler replicates the directions of light that entered the in-coupler, the waveguide substantially replicates the original image 112. A user’s eye 118 can focus on the replicated image.

[0050] In the example of FIG. 1 A, the out-coupler 114 out-couples only a portion of the light with each reflection allowing a single input beam (such as beam 108) to generate multiple parallel output beams (such as beams 116a, 116b, and 116c). In this way, at least some of the light originating from each portion of the image is likely to reach the user’s eye even if the eye is not perfectly aligned with the center of the out- coupler. For example, if the eye 118 were to move downward, beam 116c may enter the eye even if beams 116a and 116b do not, so the user can still perceive the bottom of the image 112 despite the shift in position.The out-coupler 114 thus operates in part as an exit pupil expander in the vertical direction. The waveguide may also include one or more additional exit pupil expanders (not shown in FIG. 1 A) to expand the exit pupil in the horizontal direction.

[0051] In some embodiments, the waveguide 104 is at least partly transparent with respect to light originating outside the waveguide display. For example, at least some of the light 120 from real-world objects (such as object 122) traverses the waveguide 104, allowing the user to see the real-world objects while using the waveguide display. As light 120 from real-world objects also goes through the diffraction grating 114, there will be multiple diffraction orders and hence multiple images. To minimize the visibility of multiple images, it is desirable for the diffraction order zero (no deviation by 114) to have a great diffraction efficiency for light 120 and order zero, while higher diffraction orders are lower in energy. Thus, in addition to expanding and out-coupling the virtual image, the out-coupler 114 is preferably configured to let through the zero order of the real image. In such embodiments, images displayed by the waveguide display may appear to be superimposed on the real world.

[0052] FIG. 1 B is a schematic side view illustrating an example alternative display type that may be used with extended reality applications according to some embodiments. In an XR head-mounted display device 130, a control module 132 controls a display 134, which may be an LCD, to display an image. The headmounted display includes a partly-reflective surface 136 that reflects (and in some embodiments, both reflects and focuses) the image displayed on the LCD to make the image visible to the user. The partly-reflective surface 136 also allows the passage of at least some exterior light, permitting the user to see their surroundings.

[0053] FIG. 1 C is a schematic side view illustrating an example alternative display type that may be used with extended reality applications according to some embodiments. In an XR head-mounted display device 140, a control module 142 controls a display 144, which may be an LCD, to display an image. The image is focused by one or more lenses of display optics 146 to make the image visible to the user. In the example of FIG. 1 C, exterior light does not reach the user’s eyes directly. However, in some such embodiments, an exterior camera 148 may be used to capture images of the exterior environment and display such images on the display 144 together with any virtual content that may also be displayed.

[0054] The embodiments described herein are not limited to any particular type or structure of XR display device.

[0055] FIG. 1 D is a system diagram illustrating an example set of interfaces for a system according to some embodiments. An extended reality display device, together with its control electronics, may be implemented using a system such as the system of FIG. 1 D. System 150 can be embodied as a deviceincluding the various components described below and is configured to perform one or more of the aspects described in this document. Examples of such devices, include, but are not limited to, various electronic devices such as personal computers, laptop computers, smartphones, tablet computers, digital multimedia set top boxes, digital television receivers, personal video recording systems, connected home appliances, and servers. Elements of system 150, singly or in combination, can be embodied in a single integrated circuit (IC), multiple ICs, and / or discrete components. For example, in at least one embodiment, the processing and encoder / decoder elements of system 150 are distributed across multiple ICs and / or discrete components. In various embodiments, the system 150 is communicatively coupled to one or more other systems, or other electronic devices, via, for example, a communications bus or through dedicated input and / or output ports. In various embodiments, the system 1000 is configured to implement one or more of the aspects described in this document.

[0056] The system 150 includes at least one processor 152 configured to execute instructions loaded therein for implementing, for example, the various aspects described in this document. Processor 152 may include embedded memory, input output interface, and various other circuitries as known in the art. The system 150 includes at least one memory 154 (e.g., a volatile memory device, and / or a non-volatile memory device). System 150 may include a storage device 158, which can include non-volatile memory and / or volatile memory, including, but not limited to, Electrically Erasable Programmable Read-Only Memory (EEPROM), Read-Only Memory (ROM), Programmable Read-Only Memory (PROM), Random Access Memory (RAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), flash, magnetic disk drive, and / or optical disk drive. The storage device 158 can include an internal storage device, an attached storage device (including detachable and non-detachable storage devices), and / or a network accessible storage device, as non-limiting examples.

[0057] System 150 includes an encoder / decoder module 156 configured, for example, to process data to provide an encoded video or decoded video, and the encoder / decoder module 156 can include its own processor and memory. The encoder / decoder module 156 represents module(s) that can be included in a device to perform the encoding and / or decoding functions. As is known, a device can include one or both of the encoding and decoding modules. Additionally, encoder / decoder module 156 can be implemented as a separate element of system 150 or can be incorporated within processor 152 as a combination of hardware and software as known to those skilled in the art.

[0058] Program code to be loaded onto processor 152 or encoder / decoder 156 to perform the various aspects described in this document can be stored in storage device 158 and subsequently loaded onto memory 154 for execution by processor 152. In accordance with various embodiments, one or more ofprocessor 152, memory 154, storage device 158, and encoder / decoder module 156 can store one or more of various items during the performance of the processes described in this document. Such stored items can include, but are not limited to, the input video, the decoded video or portions of the decoded video, the bitstream, matrices, variables, and intermediate or final results from the processing of equations, formulas, operations, and operational logic.

[0059] In some embodiments, memory inside of the processor 152 and / or the encoder / decoder module 156 is used to store instructions and to provide working memory for processing that is needed during encoding or decoding. In other embodiments, however, a memory external to the processing device (for example, the processing device can be either the processor 152 or the encoder / decoder module 152) is used for one or more of these functions. The external memory can be the memory 154 and / or the storage device 158, for example, a dynamic volatile memory and / or a non-volatile flash memory. In several embodiments, an external non-volatile flash memory is used to store the operating system of, for example, a television. In at least one embodiment, a fast external dynamic volatile memory such as a RAM is used as working memory for video coding and decoding operations, such as for MPEG-2 (MPEG refers to the Moving Picture Experts Group, MPEG-2 is also referred to as ISO / IEC 13818, and 13818-1 is also known as H.222, and 13818-2 is also known as H.262), HEVC (HEVC refers to High Efficiency Video Coding, also known as H.265 and MPEG-H Part 2), or VVC (Versatile Video Coding, a new standard being developed by JVET, the Joint Video Experts Team).

[0060] The inputto the elements of system 150 can be provided through various input devices as indicated in block 172. Such input devices include, but are not limited to, (i) a radio frequency (RF) portion that receives an RF signal transmitted, for example, over the air by a broadcaster, (ii) a Component (COMP) input terminal (or a set of COMP input terminals), (iii) a Universal Serial Bus (USB) input terminal, and / or (iv) a High Definition Multimedia Interface (HDMI) input terminal. Other examples, not shown in FIG. 1 C, include composite video.

[0061] In various embodiments, the input devices of block 172 have associated respective input processing elements as known in the art. For example, the RF portion can be associated with elements suitable for (i) selecting a desired frequency (also referred to as selecting a signal, or band-limiting a signal to a band of frequencies), (ii) downconverting the selected signal, (iii) band-limiting again to a narrower band of frequencies to select (for example) a signal frequency band which can be referred to as a channel in certain embodiments, (iv) demodulating the downconverted and band-limited signal, (v) performing error correction, and (vi) demultiplexing to select the desired stream of data packets. The RF portion of various embodiments includes one or more elements to perform these functions, for example, frequency selectors, signal selectors,band-limiters, channel selectors, filters, downconverters, demodulators, error correctors, and demultiplexers. The RF portion can include a tuner that performs various of these functions, including, for example, downconverting the received signal to a lower frequency (for example, an intermediate frequency or a nearbaseband frequency) or to baseband. In one set-top box embodiment, the RF portion and its associated input processing element receives an RF signal transmitted over a wired (for example, cable) medium, and performs frequency selection by filtering, downconverting, and filtering again to a desired frequency band. Various embodiments rearrange the order of the above-described (and other) elements, remove some of these elements, and / or add other elements performing similar or different functions. Adding elements can include inserting elements in between existing elements, such as, for example, inserting amplifiers and an analog-to-digital converter. In various embodiments, the RF portion includes an antenna.

[0062] Additionally, the USB and / or HDMI terminals can include respective interface processors for connecting system 150 to other electronic devices across USB and / or HDMI connections. It is to be understood that various aspects of input processing, for example, Reed-Solomon error correction, can be implemented, for example, within a separate input processing IC or within processor 152 as necessary. Similarly, aspects of USB or HDMI interface processing can be implemented within separate interface ICs or within processor 152 as necessary. The demodulated, error corrected, and demultiplexed stream is provided to various processing elements, including, for example, processor 152, and encoder / decoder 156 operating in combination with the memory and storage elements to process the datastream as necessary for presentation on an output device.

[0063] Various elements of system 150 can be provided within an integrated housing, Within the integrated housing, the various elements can be interconnected and transmit data therebetween using suitable connection arrangement 174, for example, an internal bus as known in the art, including the Inter-IC (I2C) bus, wiring, and printed circuit boards.

[0064] The system 150 includes communication interface 160 that enables communication with other devices via communication channel 162. The communication interface 160 can include, but is not limited to, a transceiver configured to transmit and to receive data over communication channel 162. The communication interface 160 can include, but is not limited to, a modem or network card and the communication channel 162 can be implemented, for example, within a wired and / or a wireless medium.

[0065] Data is streamed, or otherwise provided, to the system 150, in various embodiments, using a wireless network such as a Wi-Fi network, for example IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signal of these embodiments is received over the communications channel 162 and the communications interface 160 which are adapted for Wi-Fi communications. Thecommunications channel 162 of these embodiments is typically connected to an access point or router that provides access to external networks including the Internet for allowing streaming applications and other over-the-top communications. Other embodiments provide streamed data to the system 150 using a set-top box that delivers the data over the HDMI connection of the input block 172. Still other embodiments provide streamed data to the system 150 using the RF connection of the input block 172. As indicated above, various embodiments provide data in a non-streaming manner. Additionally, various embodiments use wireless networks other than Wi-Fi, for example a cellular network or a Bluetooth network.

[0066] The system 150 can provide an output signal to various output devices, including a display 176, speakers 178, and other peripheral devices 180. The display 176 of various embodiments includes one or more of, for example, a touchscreen display, an organic light-emitting diode (OLED) display, a curved display, and / or a foldable display. The display 176 can be for a television, a tablet, a laptop, a cell phone (mobile phone), or other device. The display 176 can also be integrated with other components (for example, as in a smart phone), or separate (for example, an external monitor for a laptop). The other peripheral devices 180 include, in various examples of embodiments, one or more of a stand-alone digital video disc (or digital versatile disc) (DVR, for both terms), a disk player, a stereo system, and / or a lighting system. Various embodiments use one or more peripheral devices 180 that provide a function based on the output of the system 150. For example, a disk player performs the function of playing the output of the system 150.

[0067] In various embodiments, control signals are communicated between the system 150 and the display 176, speakers 178, or other peripheral devices 180 using signaling such as AV.Link, Consumer Electronics Control (CEC), or other communications protocols that enable device-to-device control with or without user intervention. The output devices can be communicatively coupled to system 1000 via dedicated connections through respective interfaces 164, 166, and 168. Alternatively, the output devices can be connected to system 150 using the communications channel 162 via the communications interface 160. The display 176 and speakers 178 can be integrated in a single unit with the other components of system 150 in an electronic device such as, for example, a television. In various embodiments, the display interface 164 includes a display driver, such as, for example, a timing controller (T Con) chip.

[0068] The display 176 and speaker 178 can alternatively be separate from one or more of the other components, for example, if the RF portion of input 172 is part of a separate set-top box. In various embodiments in which the display 176 and speakers 178 are external components, the output signal can be provided via dedicated output connections, including, for example, HDMI ports, USB ports, or COMP outputs.

[0069] The system 150 may include one or more sensor devices 168. Examples of sensor devices that may be used include one or more GPS sensors, gyroscopic sensors, accelerometers, light sensors, cameras,depth cameras, microphones, and / or magnetometers. Such sensors may be used to determine information such as user’s position and orientation. Where the system 150 is used as the control module for an extended reality display (such as control modules 124, 132), the user’s position and orientation may be used in determining how to render image data such that the user perceives the correct portion of a virtual object or virtual scene from the correct point of view. In the case of head-mounted display devices, the position and orientation of the device itself may be used to determine the position and orientation of the user for the purpose of rendering virtual content. In the case of other display devices, such as a phone, a tablet, a computer monitor, or a television, other inputs may be used to determine the position and orientation of the user for the purpose of rendering content. For example, a user may select and / or adjust a desired viewpoint and / or viewing direction with the use of a touch screen, keypad or keyboard, trackball, joystick, or other input. Where the display device has sensors such as accelerometers and / or gyroscopes, the viewpoint and orientation used for the purpose of rendering content may be selected and / or adjusted based on motion of the display device.

[0070] The embodiments can be carried out by computer software implemented by the processor 152 or by hardware, or by a combination of hardware and software. As a non-limiting example, the embodiments can be implemented by one or more integrated circuits. The memory 154 can be of any type appropriate to the technical environment and can be implemented using any appropriate data storage technology, such as optical memory devices, magnetic memory devices, semiconductor-based memory devices, fixed memory, and removable memory, as non-limiting examples. The processor 152 can be of any type appropriate to the technical environment, and can encompass one or more of microprocessors, general purpose computers, special purpose computers, and processors based on a multi-core architecture, as non-limiting examples.Scene Description Framework for XR

[0071] The present principles generally relate to the domain of rendering of extended reality scene description and extended reality rendering. The present document is also understood in the context of the formatting and the playing of extended reality applications when rendered on end-user devices such as mobile devices or Head-Mounted Displays (HMD).

[0072] In XR applications, a scene description is used to combine explicit and easy-to-parse description of a scene structure and some binary representations of media content.

[0073] In time-based media streaming, the scene description itself can be time-evolving to provide the relevant virtual content for each sequence of a media stream. For instance, for advertising purpose, a virtual bottle can be displayed during a video sequence where people are drinking.

[0074] This kind of behavior can be achieved by relying on the framework defined in the Scene Description for MPEG media document, Information technology - Coded representation of immersive media - Parti 4: Scene Description for MPEG media, ISO / IEC DIS 23090-14 :2021 (E). A scene update mechanism based on the JSON Patch protocol as defined in IETF RFC 6902 may be used to synchronize virtual content to MPEG media streams.

[0075] FIG. 1 E is a system diagram illustrating an example set of interfaces for a scene description (stored as an item in gITF.json), three video tracks, an audio track, and a JSON patch update track in an ISOBMFF file according to some embodiments. FIG. 1 E is an example ISOBMFF file 190 and other elements may be in such a file.

[0076] Although the MPEG-I Scene Description framework ensures that the timed media and the corresponding relevant virtual content are available at any time, it does not provide a description of how a user can interact with the scene objects at runtime for immersive XR experiences. Hence, there is no support of user specific XR experiences for consuming the immersive media.

[0077] Example embodiments as described herein may be used to provide a scene description that includes a virtual object or light source but that does not necessarily display or render the virtual object or light source even if available. In some embodiments, one or more of the following aspects may be considered in determining whether to display a virtual object or light source.

[0078] A spatial aspect may be considered in determining whether to display a virtual object or light source. For example, if the user environment is not suited (e.g. the user is too far from the rendered timed media’s location) or if the user is not looking toward the right direction, or if the virtual object should be displayed on a user-specific area (e.g. above his left hand which is not yet detected), then the virtual object or light source may not be displayed.

[0079] A temporal aspect may be considered in determining whether to display a virtual object or light source. For example, if the user is not yet ready or wants to trigger himself the display of the object (e.g. using a specific gesture), the virtual object or light source may not be displayed until the appropriate trigger is detected.

[0080] In some embodiments, it is specified in the scene description which objects or light sources the user is allowed to manipulate or to interact with through potential haptic feedbacks.Runtime Interactivity

[0081] FIG. 2 is a system diagram illustrating an example set of interfaces for an MPEG-I node hierarchy supporting elements of scene interactivity according to some embodiments. According to the presentprinciples, in addition to the MPEG-I node hierarchy 200 of FIG. 2 and a node tree as described in relation to FIG. 4, behavior metadata items (herein called ‘behaviors’) are added to the scene description. In example embodiments, the time-evolving scene description is augmented by adding information identifying behaviors. These behaviors may be related to pre-defined virtual objects on which runtime interactivity is allowed for user specific XR experiences.

[0082] In some embodiments, these behaviors are time-evolving. In such embodiments, the behaviors may be updated through the already-existing scene description update mechanism.

[0083] In example embodiments, a behavior is characterized by one or more of the following properties:• One or more triggers defining the conditions to be met for activation.• A trigger control parameter defining the logical operations between the defined triggers.• Actions to be implemented in response to the activation of the triggers.• An action control parameter defining the order of execution of the defined actions.• A priority number enabling the selection of the behavior of highest priority in the case of concurrence of several behaviors on the same virtual object at the same time.• An optional interrupt action to specify how to terminate this behavior when the behavior is no longer defined in a newly received scene update. For instance, a behavior is no longer defined if the related object has been removed or if the behavior is no longer relevant for this current media (e.g. audio or video) sequence.

[0084] With the addition of these behaviors, time-dependent user interactivity in immersive content for XR experiences may be defined.

[0085] When a second scene description is received, some of the behaviors of the first scene description may be “on-going”, that is they are triggered, and their actions are running. The second scene description may be provided as update metadata, that is metadata describing the differences between the first scene description and the second description. The second scene description includes a node tree describing objects that may be common or different than objects of the first scene descriptions. Objects of the node tree of the first scene description may be no longer present in the second description. If the objects related to the running actions of the on-going behaviors are missing in the second scene description, then, these on-going behaviors are no longer appliable. The same way, if an on-going behavior is not defined in the second description, the on-going behavior is no longer appliable. The interrupt action field describes how to correctly interrupt the running actions on the on-going behavior.

[0086] FIG. 3 is a block diagram showing an example of logical relationships between trigger information (describing triggers 1 through n), action information (describing actions 1 through m), and behavior information (describing relationships between the triggers and actions) in which triggers and actions may refer to one or more nodes in a scene description, such as a hierarchical scene graph, according to some embodiments.

[0087] In XR applications, a scene description is used to combine explicit and easy-to-parse description of a scene structure and some binary representations of media content. The above sections describe action mechanisms for scene descriptions. These behaviors are related to pre-defined virtual objects on which runtime interactivity is allowed for user specific XR experiences. FIG. 3 illustrates the structure 300 of an example behavior mechanism. The example structure 300 shows example trigger information 302 and action information 304. Within the trigger information 302 are example triggers 1 (306), 2 (308), ... , n (310). Within the action information 304 are example triggers 1 (312), 2 (314), ... , n (316). The triggers 306, 308, 310 and actions 312, 314, 316 are shown with example relationships to various nodes 318.

[0088] FIG. 4 is a schematic plan view illustrating example relationships of extended reality scene description objects according to some embodiments. In this example, the scene graph 400 includes a description of a real object 412, for example ‘plane horizontal surface’ (that can be a table or the floor or a plate) and a description of a virtual object 414, for example an animation of a walking character. Scene graph node 414 is associated with a media content item 416 that is the encoding of data used to render and display the walking character (for example as a textured animated 3D mesh). Scene graph 400 also includes a node 410 that is a description of the spatial relation between the real object described in node 412 and the virtual object described in node 414. In this example, node 410 describes a spatial relation to make the character walk on the plane surface. When the XR application is started, media content item 416 is loaded, rendered and buffered to be displayed when triggered. When a plane surface is detected in the real environment by sensors (or a camera for some embodiments), the application displays the buffered media content item as described in node 410. The timing is managed by the application according to features detected in the real environment and to the timing of the animation. A node of a scene graph may also include no description and only play a role of a parent for child nodes.

[0089] XR applications are various and may apply to different context and real or virtual environments. For example, in an industrial XR application, a virtual 3D content item (e.g. a piece A of an engine) is displayed when a reference object (piece B of an engine) is detected in the real environment by a camera rigged on a head mounted display device. The 3D content item is positioned in the real-world with a position and a scale defined relatively to the detected reference object.

[0090] For example, in an XR application for interior design, a 3D model of a furniture is displayed when a given image from the catalog is detected in the input camera view. The 3D content is positioned in the real- world with a position and scale which is defined relatively to the detected reference image. In another application, some audio file might start playing when the user enters an area which is close to a church (being real or virtually rendered in the extended real environment). In another example, an ad jingle file may be played when the user sees a can of a given soda in the real environment. In an outdoor gaming application, various virtual characters may appear, depending on the semantics of the scenery which is observed by the user. For example, birds characters are suitable for trees, so if the sensors of the XR device detect real objects described by a semantic label ‘tree’, birds can be added flying around the trees. In a companion application implemented by smart glasses, a car noise may be launched in the user’s headset when a car is detected within the field of view of the user camera, in order to warn him of the potential danger; Furthermore, the sound may be spatialized in order to make it arrive from the direction where the car was detected.

[0091] An XR application may also augment a video content rather than a real environment. The video is displayed on a rendering device and virtual objects described in the node tree are overlaid when timed events are detected in the video. In such a context, the node tree includes only virtual objects descriptions.

[0092] Example embodiments are described with reference to the scope of the MPEG-I Scene Description framework using the Khronos gITF extension mechanism, which supports additional scene description features, such as a node tree. However, the principles described herein are not limited to a particular scene description framework.

[0093] In an example embodiment, the gITF scene description is extended to support interactivity. The interactivity extension applies at the gITF scene level and is called MPEG_scene_interactivity. The corresponding semantics are provided in Table 1.Table 1 : Semantics of an Example MPEG_scene_interactivity Extension

[0094] In Table 1 and other semantic tables described herein, the “usage” column indicates “M” for “mandatory” features and “0” for “optional” features. However, such features may be “mandatory” or “optional” only according to a particular proposed syntax. A feature marked “mandatory” is not necessarily a required feature to implement the application. For example, in some embodiments, a feature marked “mandatory” is present to satisfy the expectations of a particular type of parsing and rendering software; however, in other embodiments, that feature may be optional, or the feature may be omitted entirely, with the corresponding functionality being implemented using default values or not being implemented at all without departing from the scope of the present disclosure.

[0095] Extended reality (XR) is a technology enabling interactive experiences where the real-world environment and / or a video content is enhanced by virtual content, which can be defined across multiple sensory modalities, including visual, auditory, haptic, etc. During runtime of the application, the virtual content (3D content or audio / video file for example) is rendered in real-time in a way which is consistent with the user context (environment, point of view, device, etc.). Scene graphs (such as the one proposed by Khronos / gITF and its extensions defined in MPEG Scene Description format or Apple / USDZ for instance) are a possible way to represent the content to be rendered. They combine a declarative description of the scene structure linking real-environment objects and virtual objects on one hand, and binary representations of the virtual content on the other hand. Although such scene description frameworks ensure that the timed media and the corresponding relevant virtual content are available at any time during the rendering of the application, there is no description of how to handle conditional, event-based interactive events within an MPEG-I Scene Description (SD) environment.

[0096] This application discusses 3D scenes and object interactions within immersive environments. Described herein is a generic conditional trigger that allow use of additional information to activate the trigger. This set of triggers may be used with the MPEG-I Scene Description (SD) to support interactivity in 3Denvironments from generic metadata information present in nodes with corresponding time-based events. The current interactivity support at the scene level only supports generic triggers for any node in the scene, as illustrated in Table 2. Hence a problem arises if a node contains information that may be used to trigger an interactive event because the current interactivity framework of the MPEG-I SD does not allow such conditional event-based signaling. See MPEG Extension.Table 2: List of Triggers Currently Available for MPEG_scene_interactivity

[0097] In the interactivity framework, “Behaviors” are a set of conditions that pair triggered events with specific actions and delineate temporal constraints of such conditions, allowing time-based events to occur in 3D virtual environments. The “Actions” are modifiers to 3D nodes that may impact their spatial position, their material, the media controls, or haptic feedback. The “Triggers” are events that happen between nodes or users. Table 2 shows a list of triggers currently available for MPEG_scene_interactivity, which may be found at Table 8.2-3 of MPEG Extension.

[0098] The sections below present new extensions that allow gITF models to use and interact with other 3D objects through metadata information present in nodes. These sections introduce a new conditional trigger. These additions may be applied at the scene level in the “MPEG_scene_interactivity” section and may be extended to the node level if required, e.g., in certain implementations.Conditional Triggers

[0099] The following sections detail the elements, with the associated meaning, JSON coding schemes, and how they may be used within the MPEG-I SD.

[0100] The format follows the gITF format and is compatible with the current MPEG effort to extend the gITF format with MPEG extensions. However, the meaning and use are “generic” and may be coded with other formats, such as Extensible Markup Language (XML) and Universal Scene Description (USD).

[0101] Table 3 introduces generic conditional triggers (e.g.,“TRIGGER_CONDITIONAL”), which is added at the same hierarchical level as the list of original triggers shown above in Table 2. The new generic conditional trigger may be added to the list shown in Table 2 (see Table 4). A generic conditional trigger mayinclude a “generic” path to one or more parameters for some embodiments. The trigger condition may be configured via such parameters stored at the location of the generic path. As such, the specific parameters used for the trigger may not necessarily be specified in a table, but rather may be configured and / or updated at runtime for some embodiments. For some embodiments, a default set of parameters may be specified or stored at start-up (or prior to start-up) and may be updated later. For example, a separate condition may occur, and the parameters stored at the generic path may be updated. Many trigger parameters are possible in accordance with the embodiments disclosed and contemplated herein. For example, for some embodiments, the specific trigger parameters may be updated to follow the evolution of a standard or specification.Table 3: Conditional Trigger Semantics

[0102] For some embodiments, the attribute “descriptor” may be a string or an array of strings. The attribute “descriptor” compares multiple schemes to the given values in the “parameters” attribute.Table 4: Trigger List for MPEG_scene_interactivity Plus a Generic Conditional TriggerConditional Triggers Pre-Processing

[0103] FIG. 5 is a flowchart illustrating example pre-processing of a conditional trigger according to some embodiments. FIG. 6 is a flowchart illustrating example pre-processing of a conditional trigger according to some embodiments. FIG. 7 is a flowchart illustrating example pre-processing of a conditional trigger according to some embodiments. FIGs. 5, 6, and 7 demonstrate pre-processing of the conditional triggers used in immersive and interactive systems and discussed above. This pre-processing is done to validate the constructors of the behaviors and triggers.

[0104] FIGs. 5, 6, and 7 each show an example process 500, 600, 700 for an application that may parse 502, 602, 702 each trigger present in a behavior and evaluate its condition. For FIGs. 5, 6, and 7, a trigger check 504, 604, 704 is performed.

[0105] For FIGs. 5, 6, and 7, if a conditional trigger is encountered, a check 506, 608, 716 is done to see if the nodes listed in the trigger contain the descriptor, which is a path to the node value to be compared. If the current trigger is not a conditional trigger, processing proceeds to handle other triggers. If the descriptor is not found in any of the nodes, an error may be indicated 508, 610, 718. Such an indication may be handled by the model signalling the application (or any other engine that processes such interactive models) that this trigger and the current behavior will not be validated if the list of nodes is not changed. This allows the engine to optimize its computation and ignore or correct behaviors at the parsing stage that may never complete. If all nodes include the descriptor and are thus conditional trigger extension nodes, processing, e.g., parsing of triggers, continues 510, 612, 720. For some embodiments, these restrictions shown in FIGs. 5-7 may be applied to Table 3 shown above.

[0106] For FIGs. 6 and 7, if the current trigger is not a conditional trigger, processing moves on to handle 606, 706 other triggers. For FIG. 7, if the current trigger is not conditional trigger, an “enum” (enumeration) may be executed to jump to the appropriate non-conditional trigger block 708, 710, 712, 714 for some embodiments (with some example triggers listed in FIG. 7).

[0107] At runtime, a processing model may remain unchanged to the original interactive model. For example, if a condition is not met, the application continues. If all trigger conditions are met for the behavior being evaluated, its actions will be launched for some embodiments. If one or more of the conditions are not met for one of the triggers, the application continues to evaluate scene updates until all the trigger conditions are satisfied for some embodiments. In some embodiments, if one or more of the conditions are not met for one of the triggers, the application continues to evaluate every scene update until all the trigger conditions are satisfied.gITF Schema Example

[0108] The following gITF schema is an example (not exhaustive) instantiation of triggers used by clients that supports “MPEG_scene_interactivity”. A huge number of instantiations are possible, depending on the application, and the following sections give several examples for illustration purposes.

[0109] FIGs. 8A-8B form a code listing illustrating an example code structure for base scene elements according to some embodiments. FIGs. 8A and 8B work together to show an example code listing 800, 850 for some base scene elements. There are two nodes. The first node is a camera (lines 3 to 35 of FIG. 8A) with an avatar node extension (lines 17 to 34 of FIG. 8A), and the second node is a sphere node (lines 36 to 44 of FIG. 8A). These elements are used with the example code listings shown in FIGs. 9A to 10B.

[0110] FIG. 9 is a code listing illustrating an example code structure for a conditional trigger metadata according to some embodiments. This example code listing 900 shows how conditional triggers may be used to trigger interactions with an object in the scene based on conditions of metadata information associated with an avatar (lines 20 to 32 of FIG. 8A). In this example, the defined behavior uses both a proximity trigger (lines 7 to 12 of FIG. 9) and a conditional trigger (lines 13 to 23 of FIG. 9) to start an action. The combined trigger is true when the avatar comes within a distance between 0.0 and 1 .0 unit of the red sphere and the age of the avatar (or person using the avatar) is 18 years or higher.

[0111] In this example, there are two nodes from the base scene shown in FIGs. 8A and 8B. The first node is a camera with an avatar node extension, and the second node is a sphere node for illustration of interactions. These objects are examples of the types of objects that may be in a scene.

[0112] This example instantiates the trigger trigger_conditional. The behavior class instantiates a behavior for the trigger paired with the trigger trigger_proximity, e.g., trigger_proximity and trigger_ conditional, so the two objects, e.g., avatar and sphere, may have a two-step interaction. This operation means that the proximity trigger (lines 7 to 12 of FIG. 9) is fired before the second trigger is fired for some embodiments.

[0113] In this example, the value being compared (“18”) (line 18 of FIG. 9) and the comparator used (“greaterThanOrEqualTo”) (line 19 of FIG. 9) are both specified through the conditional trigger. The attribute to look for in the node is specified through a naming convention (“node.MPEG_node_avatar.metadata.age”) (line 15 of FIG. 9) of the conditional trigger. In this example, since node 0 (the avatar) has a value greater than or equal to the value being compared (“18”), the activate action (“ACTION_ACTIVATE”) launches, and the application interacts accordingly.

[0114] FIGs. 10A-10B form a code listing illustrating an example code structure for a conditional trigger according to some embodiments. This second example code listing 1000, 1050 illustrates how conditionaltriggers may be used with multiple parameters for different types of comparisons to limit interactions. In this example, the action associated with the behavior is triggered based on a proximity trigger and multiple conditions in metadata information of an avatar, although these conditions are of course merely examples.

[0115] In this example, there are two nodes from the base scene shown in FIGs. 8A and 8B. The first node is a camera with an avatar node extension, and the second node is a sphere node for illustration of interactions. These objects are examples of the types of objects that may be in a scene.

[0116] This example instantiates the trigger trigger_conditional. The behavior class instantiates a behavior for the trigger paired with trigger_proximity, e.g., trigger_proximity and trigger_ conditional, so the two objects, e.g., avatar and sphere, may have a two-step interaction. This operation means that the proximity trigger (lines 7 to 12 of FIG. 10A) is fired before the second trigger is fired for some embodiments.

[0117] This example is similar to the example shown in FIG. 9. The difference is that multiple attributes (lines 15 to 24 of FIG. 10A and lines 1 to 33 of FIG. 10B) may be compared using a single conditional trigger. For this example, the “descriptor” attribute is an array that has an index aligned with the “parameters” attribute array.

[0118] In this example, the conditional trigger is based on multiple parameter comparisons, but each of those parameters is defined generically using a PATH designation relative to the schema. See, e.g., the line “node.MPEG_node_avatar.metadata.capability” in FIG. 10A for an example of such a designation. The example of FIGs. 10A and 10B shows the complexity and flexibility of the new conditional trigger. For some embodiments, the conditional trigger may be entirely defined in the schema and not in a syntax table that defines the trigger.

[0119] FIG. 11 is a flowchart illustrating an example process for processing a conditional trigger according to some embodiments. For some embodiments, an example process 1100 may include obtaining 1102 scene description data for a three-dimensional (3D) scene. For some embodiments of the example process 1000, the scene description data may include 1104 behavior information including: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition includes a conditional trigger. For some embodiments, the example process 1100 may further include responsive to determining that the at least one trigger condition has occurred, performing 1106 the action on the scene element.

[0120] While the methods and systems in accordance with some embodiments are generally discussed in context of extended reality (XR), some embodiments may be applied to any XR contexts such as, e.g., virtual reality (VR) / mixed reality (MR) / augmented reality (AR) contexts. Also, although the term “headmounted display (HMD)” is used herein in accordance with some embodiments, some embodiments may be applied to a wearable device (which may or may not be attached to the head) capable of, e.g., XR, VR, AR, and / or MR for some embodiments.

[0121] An example method in accordance with some embodiments may include: obtaining scene description data for a three-dimensional (3D) scene, wherein the scene description data includes behavior information including: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition includes a conditional trigger; and wherein the trigger information includes a path to an attribute, wherein the attribute is used with the conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

[0122] For some embodiments of the example method, the at least one trigger condition includes a test on the attribute.

[0123] An example apparatus in accordance with some embodiments may include: a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform the method of any one of the claims listed above.

[0124] An example method in accordance with some embodiments may include: obtaining scene description data for a three-dimensional (3D) scene, wherein the scene description data includes behavior information, which may include: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition may include a conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

[0125] For some embodiments of the example method, the at least one conditional trigger may include a path to a storage location, and the trigger information describing the at least one trigger condition is stored at the storage location.

[0126] Some embodiments of the example method may further include updating the trigger information at runtime.

[0127] Some embodiments of the example method may further include updating the trigger information prior to runtime.

[0128] Some embodiments of the example method may further include updating the conditional trigger at runtime.

[0129] Some embodiments of the example method may further include updating the conditional trigger prior to runtime.

[0130] For some embodiments of the example method, the trigger information may include one or more parameters, and the at least one trigger condition may be based on at least one of the one or more parameters.

[0131] For some embodiments of the example method, at least one of the one or more parameters may include a value field and a comparator field.

[0132] For some embodiments of the example method, the trigger information further includes node information indicating one or more nodes, and the method further includes: searching a memory structure corresponding to the one or more nodes for a field matching the value field; and updating the conditional trigger based on the matching field.

[0133] For some embodiments of the example method, the trigger information further includes a descriptor field, and the method further includes using the descriptor field with the one or more parameters to determine the at least one trigger condition.

[0134] Some embodiments of the example method may further include: detecting a second condition; and responsive to detecting the second condition, updating the trigger information.

[0135] For some embodiments of the example method, the trigger information may further include at least one metadata field.

[0136] For some embodiments of the example method, the at least one trigger condition is based on the at least one metadata field.

[0137] For some embodiments of the example method, the conditional trigger may include two or more conditions.

[0138] For some embodiments of the example method, the at least one conditional trigger includes a path to a parameter to be compared, and the at least one trigger condition includes the parameter to be compared.

[0139] For some embodiments of the example method, the at least one trigger condition includes a test on the attribute.

[0140] An example apparatus in accordance with some embodiments may include: a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform any one of the methods listed above.

[0141] Another example method in accordance with some embodiments may include handling a conditional trigger related to a three-dimensional (3D) scene, wherein the conditional trigger may include a mechanism for updating one or more trigger conditions related to the conditional trigger.

[0142] An example apparatus in accordance with some embodiments may include: a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform the method listed above.

[0143] A further example method in accordance with some embodiments may include: obtaining scene description data for a three-dimensional (3D) scene, wherein the scene description data includes behavior information including: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition includes a conditional trigger; and wherein the trigger information includes a path to an attribute, wherein the attribute is used with the conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

[0144] For some embodiments of the further example method, the at least one trigger condition includes a test on the attribute.

[0145] A further example apparatus in accordance with some embodiments may include a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform any one of the methods listed above.

[0146] This disclosure describes a variety of aspects, including tools, features, embodiments, models, approaches, etc. Many of these aspects are described with specificity and, at least to show the individual characteristics, are often described in a manner that may sound limiting. However, this is for purposes of clarity in description, and does not limit the disclosure or scope of those aspects. Indeed, all of the different aspects can be combined and interchanged to provide further aspects. Moreover, the aspects can be combined and interchanged with aspects described in earlier filings as well.

[0147] The aspects described and contemplated in this disclosure can be implemented in many different forms. While some embodiments are illustrated specifically, other embodiments are contemplated, and the discussion of particular embodiments does not limit the breadth of the implementations. At least one of the aspects generally relates to video encoding and decoding, and at least one other aspect generally relates to transmitting a bitstream generated or encoded. These and other aspects can be implemented as a method, an apparatus, a computer readable storage medium having stored thereon instructions for encoding ordecoding video data according to any of the methods described, and / or a computer readable storage medium having stored thereon a bitstream generated according to any of the methods described.

[0148] In the present disclosure, the terms “reconstructed” and “decoded” may be used interchangeably, the terms “pixel” and “sample” may be used interchangeably, the terms “image,” “picture” and “frame” may be used interchangeably. Usually, but not necessarily, the term “reconstructed” is used at the encoder side while “decoded” is used at the decoder side.

[0149] The terms HDR (high dynamic range) and SDR (standard dynamic range) often convey specific values of dynamic range to those of ordinary skill in the art. However, additional embodiments are also intended in which a reference to HDR is understood to mean “higher dynamic range” and a reference to SDR is understood to mean “lower dynamic range.” Such additional embodiments are not constrained by any specific values of dynamic range that might often be associated with the terms “high dynamic range” and “standard dynamic range.”

[0150] Various methods are described herein, and each of the methods comprises one or more steps or actions for achieving the described method. Unless a specific order of steps or actions is required for proper operation of the method, the order and / or use of specific steps and / or actions may be modified or combined. Additionally, terms such as “first”, “second”, etc. may be used in various embodiments to modify an element, component, step, operation, etc., such as, for example, a “first decoding” and a “second decoding”. Use of such terms does not imply an ordering to the modified operations unless specifically required. So, in this example, the first decoding need not be performed before the second decoding, and may occur, for example, before, during, or in an overlapping time period with the second decoding.

[0151] Various numeric values may be used in the present disclosure, for example. The specific values are for example purposes and the aspects described are not limited to these specific values.

[0152] Embodiments described herein may be carried out by computer software implemented by a processor or other hardware, or by a combination of hardware and software. As a non-limiting example, the embodiments can be implemented by one or more integrated circuits. The processor can be of any type appropriate to the technical environment and can encompass one or more of microprocessors, general purpose computers, special purpose computers, and processors based on a multi-core architecture, as nonlimiting examples.

[0153] Various implementations involve decoding. “Decoding”, as used in this disclosure, can encompass all or part of the processes performed, for example, on a received encoded sequence in order to produce a final output suitable for display. In various embodiments, such processes include one or more of theprocesses typically performed by a decoder, for example, entropy decoding, inverse quantization, inverse transformation, and differential decoding. In various embodiments, such processes also, or alternatively, include processes performed by a decoder of various implementations described in this disclosure, for example, extracting a picture from a tiled (packed) picture, determining an upsampling filter to use and then upsampling a picture, and flipping a picture back to its intended orientation.

[0154] As further examples, in one embodiment “decoding” refers only to entropy decoding, in another embodiment “decoding” refers only to differential decoding, and in another embodiment “decoding” refers to a combination of entropy decoding and differential decoding. Whether the phrase “decoding process” is intended to refer specifically to a subset of operations or generally to the broader decoding process will be clear based on the context of the specific descriptions.

[0155] Various implementations involve encoding. In an analogous way to the above discussion about “decoding”, “encoding” as used in this disclosure can encompass all or part of the processes performed, for example, on an input video sequence in order to produce an encoded bitstream. In various embodiments, such processes include one or more of the processes typically performed by an encoder, for example, partitioning, differential encoding, transformation, quantization, and entropy encoding. In various embodiments, such processes also, or alternatively, include processes performed by an encoder of various implementations described in this disclosure.

[0156] As further examples, in one embodiment “encoding” refers only to entropy encoding, in another embodiment “encoding” refers only to differential encoding, and in another embodiment “encoding” refers to a combination of differential encoding and entropy encoding. Whether the phrase “encoding process” is intended to refer specifically to a subset of operations or generally to the broader encoding process will be clear based on the context of the specific descriptions.

[0157] Various embodiments refer to rate distortion optimization. In particular, during the encoding process, the balance or trade-off between the rate and distortion is usually considered, often given the constraints of computational complexity. The rate distortion optimization is usually formulated as minimizing a rate distortion function, which is a weighted sum of the rate and of the distortion. There are different approaches to solve the rate distortion optimization problem. For example, the approaches may be based on an extensive testing of all encoding options, including all considered modes or coding parameters values, with a complete evaluation of their coding cost and related distortion of the reconstructed signal after coding and decoding. Faster approaches may also be used, to save encoding complexity, in particular with computation of an approximated distortion based on the prediction or the prediction residual signal, not the reconstructed one. A mix of these two approaches can also be used, such as by using an approximateddistortion for only some of the possible encoding options, and a complete distortion for other encoding options. Other approaches only evaluate a subset of the possible encoding options. More generally, many approaches employ any of a variety of techniques to perform the optimization, but the optimization is not necessarily a complete evaluation of both the coding cost and related distortion.

[0158] When a figure is presented as a flow diagram, it should be understood that it also provides a block diagram of a corresponding apparatus. Similarly, when a figure is presented as a block diagram, it should be understood that it also provides a flow diagram of a corresponding method / process.

[0159] The implementations and aspects described herein can be implemented in, for example, a method or a process, an apparatus, a software program, a data stream, or a signal. Even if only discussed in the context of a single form of implementation (for example, discussed only as a method), the implementation of features discussed can also be implemented in other forms (for example, an apparatus or program). An apparatus can be implemented in, for example, appropriate hardware, software, and firmware. The methods can be implemented in, for example, a processor, which refers to processing devices in general, including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. Processors also include communication devices, such as, for example, computers, cell phones, portable / personal digital assistants (“PDAs”), and other devices that facilitate communication of information between end-users.

[0160] Reference to “one embodiment” or “an embodiment” or “one implementation” or “an implementation”, as well as other variations thereof, means that a particular feature, structure, characteristic, and so forth described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase “in one embodiment” or “in an embodiment” or “in one implementation” or “in an implementation”, as well any other variations, appearing in various places throughout this disclosure are not necessarily all referring to the same embodiment.

[0161] Additionally, this disclosure may refer to “determining” various pieces of information. Determining the information can include one or more of, for example, estimating the information, calculating the information, predicting the information, or retrieving the information from memory.

[0162] Further, this disclosure may refer to “accessing” various pieces of information. Accessing the information can include one or more of, for example, receiving the information, retrieving the information (for example, from memory), storing the information, moving the information, copying the information, calculating the information, determining the information, predicting the information, or estimating the information.

[0163] Additionally, this disclosure may refer to “receiving” various pieces of information. Receiving is, as with “accessing”, intended to be a broad term. Receiving the information can include one or more of, forexample, accessing the information, or retrieving the information (for example, from memory). Further, “receiving” is typically involved, in one way or another, during operations such as, for example, storing the information, processing the information, transmitting the information, moving the information, copying the information, erasing the information, calculating the information, determining the information, predicting the information, or estimating the information.

[0164] It is to be appreciated that the use of any of the following ”, “and / or”, and “at least one of’, for example, in the cases of “A / B”, “A and / or B” and “at least one of A and B”, is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of both options (A and B). As a further example, in the cases of “A, B, and / or C” and “at least one of A, B, and C”, such phrasing is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of the third listed option (C) only, or the selection of the first and the second listed options (A and B) only, or the selection of the first and third listed options (A and C) only, or the selection of the second and third listed options (B and C) only, or the selection of all three options (A and B and C). This may be extended for as many items as are listed.

[0165] Also, as used herein, the word “signal” refers to, among other things, indicating something to a corresponding decoder. For example, in certain embodiments the encoder signals a particular one of a plurality of parameters for region-based filter parameter selection for de-artifact filtering. In this way, in an embodiment the same parameter is used at both the encoder side and the decoder side. Thus, for example, an encoder can transmit (explicit signaling) a particular parameter to the decoder so that the decoder can use the same particular parameter. Conversely, if the decoder already has the particular parameter as well as others, then signaling can be used without transmitting (implicit signaling) to simply allow the decoder to know and select the particular parameter. By avoiding transmission of any actual functions, a bit savings is realized in various embodiments. It is to be appreciated that signaling can be accomplished in a variety of ways. For example, one or more syntax elements, flags, and so forth are used to signal information to a corresponding decoder in various embodiments. While the preceding relates to the verb form of the word “signal”, the word “signal” can also be used herein as a noun.

[0166] Implementations can produce a variety of signals formatted to carry information that can be, for example, stored or transmitted. The information can include, for example, instructions for performing a method, or data produced by one of the described implementations. For example, a signal can be formatted to carry the bitstream of a described embodiment. Such a signal can be formatted, for example, as an electromagnetic wave (for example, using a radio frequency portion of spectrum) or as a baseband signal. The formatting can include, for example, encoding a data stream and modulating a carrier with the encodeddata stream. The information that the signal carries can be, for example, analog or digital information. The signal can be transmitted over a variety of different wired or wireless links, as is known. The signal can be stored on a processor-readable medium.

[0167] We describe a number of embodiments. Features of these embodiments can be provided alone or in any combination, across various claim categories and types. Further, embodiments can include one or more of the following features, devices, or aspects, alone or in any combination, across various claim categories and types:• A bitstream or signal that includes one or more of the described syntax elements, or variations thereof.• A bitstream or signal that includes syntax conveying information generated according to any of the embodiments described.• Creating and / or transmitting and / or receiving and / or decoding a bitstream or signal that includes one or more of the described syntax elements, or variations thereof.• Creating and / or transmitting and / or receiving and / or decoding according to any of the embodiments described.• A method, process, apparatus, medium storing instructions, medium storing data, or signal according to any of the embodiments described.

[0168] Note that various hardware elements of one or more of the described embodiments are referred to as “modules” that carry out (i.e., perform, execute, and the like) various functions that are described herein in connection with the respective modules. As used herein, a module includes hardware (e.g., one or more processors, one or more microprocessors, one or more microcontrollers, one or more microchips, one or more application-specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more memory devices) deemed suitable by those of skill in the relevant art for a given implementation. Each described module may also include instructions executable for carrying out the one or more functions described as being carried out by the respective module, and it is noted that those instructions could take the form of or include hardware (i.e., hardwired) instructions, firmware instructions, software instructions, and / or the like, and may be stored in any suitable non-transitory computer-readable medium or media, such as commonly referred to as RAM, ROM, etc.

[0169] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer orprocessor. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

CLAIMS1. A method comprising: obtaining scene description data for a three-dimensional (3D) scene, wherein the scene description data comprises behavior information comprising: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition comprises a conditional trigger; and wherein the trigger information comprises a path to an attribute, wherein the attribute is used with the conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

2. The method of claim 1 , wherein the at least one trigger condition comprises a test on the attribute.

3. An apparatus comprising: a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform the method of any one of claims 1 through 2.

4. A method comprising: obtaining scene description data for a three-dimensional (3D) scene, wherein the scene description data comprises behavior information comprising: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition comprises a conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

5. The method of claim 4, wherein the at least one conditional trigger comprises a path to a storage location, and wherein the trigger information describing the at least one trigger condition is stored at the storage location.

6. The method of any one of claims 4-5, further comprising updating the trigger information at runtime.

7. The method of any one of claims 4-5, further comprising updating the trigger information prior to runtime.

8. The method of any one of claims 4-7, further comprising updating the conditional trigger at runtime.

9. The method of any one of claims 4-7, further comprising updating the conditional trigger prior to runtime.

10. The method of any one of claims 4-9, wherein the trigger information comprises one or more parameters, and wherein the at least one trigger condition is based on at least one of the one or more parameters.11 . The method of claim 10, wherein at least one of the one or more parameters comprises a value field and a comparator field.

12. The method of any one of claims 10-11 , wherein the trigger information further comprises node information indicating one or more nodes, and wherein the method further comprises: searching a memory structure corresponding to the one or more nodes for a field matching the value field; and updating the conditional trigger based on the matching field.

13. The method of any one of claims 4-12, wherein the trigger information further comprises a descriptor field, and wherein the method further comprises using the descriptor field with the one or more parameters to determine the at least one trigger condition.

14. The method of any one of claims 4-13, further comprising: detecting a second condition; and responsive to detecting the second condition, updating the trigger information.

15. The method of any one of claims 4-14, wherein the trigger information comprises at least one metadata field.

16. The method of any one of claims 4-15, wherein the at least one trigger condition is based on the at least one metadata field.

17. The method of any one of claims 4-16, wherein the conditional trigger comprises two or more conditions.

18. The method of any one of claims 4-17, wherein the at least one conditional trigger comprises a path to a parameter to be compared, and wherein the at least one trigger condition comprises the parameter to be compared.

19. The method of any one of claims 4-18, wherein the at least one trigger condition comprises a test on the attribute.

20. An apparatus comprising: a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform the method of any one of claims 4 through 19.

21. A method comprising handling a conditional trigger related to a three-dimensional (3D) scene, wherein the conditional trigger comprises a mechanism for updating one or more trigger conditions related to the conditional trigger.

22. An apparatus comprising: a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatus to perform the method of claim 21 .

23. A method comprising: obtaining scene description data for a three-dimensional (3D) scene, wherein the scene description data comprises behavior information comprising: trigger information describing at least one trigger condition, and action information describing an action to perform on a scene element in the 3D scene, wherein the at least one trigger condition comprises a conditional trigger; and wherein the trigger information comprises a path to an attribute, wherein the attribute is used with the conditional trigger; and responsive to determining that the at least one trigger condition has occurred, performing the action on the scene element.

24. The method of claim 23, wherein the at least one trigger condition comprises a test on the attribute.

25. An apparatus comprising:a processor; and a memory storing instructions operative, when executed by the processor, to cause the apparatusrform the method of any one of claims 23 through 24.

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