Physics simulation in scene description

Abstract

In a method according to some embodiments, a scene description file is obtained. At least one value of a physics parameter is read from the scene description file. A physics engine used by a runtime application is determined. A parameter mapping is identified based on the determined physics engine, wherein the mapping associates physics parameters with physics engine variables. The value of the physics parameter is assigned to a physics engine variable according to the identified mapping. In some embodiments, the physics parameter is at least one of the following: a gravity parameter, a maximum frame time, a bounce threshold, a collision detection mode, a linear drag coefficient, and / or an angular drag coefficient.

Description

PHYSICS SIMULATION IN SCENE DESCRIPTIONCROSS-REFERENCE

[0001] This application claims the priority of European Patent Application No. 23306634.9, filed 29 September 2023, entitled “Physics Simulation In Scene Description,” which is incorporated herein by reference in its entirety.BACKGROUND

[0002] The present disclosure generally relates to the encoding, decoding and rendering of 3D scenes. The present document is also understood in the context of the formatting and the playing of augmented reality and extended reality applications when rendered on end-user devices such as mobile devices or Head-Mounted Displays (HMD). 3D scenes may by represented by a runtime asset delivery file such as a gITF file. A runtime asset delivery file can provide information on a 3D scene, including the geometry and organization of objects in the scene and information used to animate those objects. Scene graphs (such as the one proposed by Khronos I gITF and its extensions defined in MPEG Scene Description format or Apple I 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.

[0003] Some attempts have been made to allow real-time game engines to perform physics simulations in 3D scenes in an interoperable way. Scene description files may include parameters such as “usePhysics”, “useGravity”, “mass”, “restitution”, staticFriction”, and “dynamicFriction” that can in theory be used by different game engines. However, some experiments have performed with different game engines (such as Unreal Engine and Unity), and it has been found that, even using the same parameters as specified above, the different game engines do not reliably provide the same simulation of a 3D scene.SUMMARY

[0004] A method according to some embodiments comprises: obtaining a scene description file; reading at least one value of a physics parameter from the scene description file; determining a physics engine used by a runtime application; identifying a parameter mapping based on the determined physics engine, wherein the mapping associates physics parameterswith physics engine variables; and assigning the value of the physics parameter to a physics engine variable according to the identified mapping.

[0005] In some embodiments, the physics parameter is at least one of the following: a gravity parameter, a maximum frame time, a bounce threshold, a collision detection mode, a linear drag coefficient, and / or an angular drag coefficient.

[0006] In some embodiments, at least one of the physics parameters is obtained from a scene-level extension in the scene description file.

[0007] In some embodiments, at least one of the physics parameters is obtained from a nodelevel extension in the scene description file.

[0008] Some embodiments further comprise reading a flag in the scene description file and determining that the flag is true, wherein at least one of the physics parameters is obtained from the scene description file only in response to the determination that the flag is true.

[0009] In some embodiments, the parameter mapping is selected from among a plurality of parameter mappings, including a first parameter mapping that maps a first physics parameter to a first physics engine variable and a second mapping that maps the first physics parameter to a second physics engine variable, wherein the first and second physics engine variables have different semantics. In some such embodiments, the first physics engine variable is a maximum interval and the second physics engine variable is a fixed interval.

[0010] A method according to some embodiments comprises: authoring a scene using a physics engine configured with at least one variable; encoding the scene in a scene description file; identifying a parameter mapping based on the physics engine; assigning the variable to a physics parameter based on the mapping; and encoding the physics parameter in the scene description file.

[0011] In some embodiments, the physics parameter is at least one of the following: a gravity parameter, a maximum frame time, a bounce threshold, a collision detection mode, a linear drag coefficient, and / or an angular drag coefficient.

[0012] In some embodiments, the physics parameter is at least one of the following: a gravity parameter, a maximum frame time, a bounce threshold, a collision detection mode, a linear drag coefficient, and / or an angular drag coefficient.

[0013] In some embodiments, at least one of the physics parameters is encoded in a scenelevel extension in the scene description file.

[0014] In some embodiments, at least one of the physics parameters is encoded in a nodelevel extension in the scene description file.

[0015] Some embodiments further comprise encoding a flag in the scene description file, wherein a value of the flag is based on whether a first one of the physics parameters is encoded in the scene description file.

[0016] In some embodiments, the parameter mapping is selected from among a plurality of parameter mappings, including a first parameter mapping that maps a first physics parameter to a first physics engine variable and a second mapping that maps the first physics parameter to a second physics engine variable, wherein the first and second physics engine variables have different semantics. In some such embodiments, the first physics engine variable is a maximum interval and the second physics engine variable is a fixed interval.

[0017] Additional embodiments include an apparatus comprising one or more processors configured to perform any of the methods described herein.

[0018] Additional embodiments include an apparatus comprising at least one processor and a computer-readable medium (which may be non-transitory) storing instructions for performing any of the methods described herein.

[0019] Additional embodiments include a computer-readable medium storing instructions for performing any of the methods described herein.

[0020] Additional embodiments include a computer-readable medium storing a scene encoded according to any of the methods described herein.

[0021] Additional embodiments include a signal conveying a scene encoded according to any of the methods disclosed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a flow chart illustrating the processing of a scene description file including physics parameters according to some embodiments.

[0023] FIG. 2 is a flow chart illustrating the setting of variables in a physics engine according to some embodiments.

[0024] FIG. 3 is a flow chart illustrating the encoding of a scene description file using physics parameters based on variables from a physics engine.

[0025] FIG. 4 is a functional block diagram of a system that may be used to implement some embodiments.DETAILED DESCRIPTION

[0026] Example embodiments provide for the encoding, decoding, and processing of scene description files that include parameters that allow for improved interoperability between game engines. In some embodiments, these parameters are included in a scene description file, for example they may be provided at the scene level e.g. in the MPEG_scene_interactivity extension.

[0027] In some embodiments, a parameter is provided to indicate a collision detection mode. This parameter may identify the mode to be used by the game engine for collision detection. For example, the parameter may indicate whether the collision detection calculation mode is discrete (e.g. calculated once for each frame) or continuous dynamic (e.g. calculated more than once for each frame).

[0028] In some embodiments, a parameter is provided to indicate a physics maximum time frame. This parameter may be used to indicate a maximum time allowed forthe physics engine to run in an update loop. For example if the parameter is set to 0.02, the engine will run 50 times / second.

[0029] In some embodiments, a parameter is provided to indicate a bounce threshold. This parameter may be used to indicate a relative velocity threshold such that bodies that contact each other with a relative velocity below this threshold will not bounce.

[0030] In some embodiments, a parameter is provided to indicate a level of linear damping. This parameter may be used to indicate the linear drag coefficient (the rate of decrease of the linear velocity over time).

[0031] In some embodiments, a parameter is provided to indicate a level of angular damping. This parameter may be used to indicate an angular drag coefficient (the rate of decrease of the angular velocity over time).

[0032] In some embodiments, a parameter is provided to indicate a level of gravity. This parameter may be used to indicate the strength of gravity for the physics simulations.

[0033] In some embodiments a flag may be provided to indicate whether or not one or more of the other parameters are provided. For example, a flag such as “enableHighPrecision” may be provided. In some embodiments, when this flag is set to TRUE, the parameters “physicMaxFrameTime” and “bounceThreshold” may be provided, and they may otherwise be excluded.

[0034] In some embodiments, one or more parameters are provided at the node level (e.g. in the MPEG_node_interactivity extension) to have more control over the physics simulation ofeach individual objects. For example, parameters such as “collisionDetectionMode”, “linearDamping”, and / or “angularDamping” may be provided as node-level parameters.

[0035] Table 1 illustrates parameters that may be included in a scene-level extension such as “MPEG_scene_interactivity”. The parameters indicated with a dagger (t) are parameters and associated syntax that are introduced in the present disclosure. While some embodiments may include all of the presented parameters, other embodiments may include only some of the parameters, e.g. only one of the parameters.Table 1.

[0036] In Table 1 and other tables herein, the “usage” column indicates whether a particular parameter is mandatory (M) or optional (O) according to the specific embodiment shown in the table. However, the fact that a parameter is marked as “mandatory” for the embodiment shown by the particular table should not be taken to imply that the parameter is mandatory (or even used at all) in a different embodiment.

[0037] Table 2 illustrates parameters that may be included in a node-level extension such as “MPEG_node_interactivity”. The parameters indicated with a dagger (t) are parameters and associated syntax that are introduced in the present disclosure. While some embodiments may include all of the presented parameters, other embodiments may include only some of the parameters, e.g. only one of the parameters.Table 2.

[0038] In some embodiments, the “enableHighPrecision” flag and the “gravity” value may be provided at the scene level but in an extension other than the MPEG_scene_interactivity extension. For example, some embodiments use an extension that may be called, for example, “MPEG_scene_physics.” An example of the syntax and semantics of such an extension is provided in Table 3.Table 3.Processing model

[0039] In some embodiments, processing of a scene description file is performed as illustrated in the flow chart of FIG. 1 . When the scene description file becomes available, e.g. when the application receives and starts parsing a scene description file (102), the file may be processed as follows. One or more of the physics parameters are obtained (104) from a scenelevel extension, which may be a dedicated extension (e.g., MPEG_scene_physics) or an extension that includes interactivity parameters (e.g. the MPEGJnteractivity extension). The scene level physics parameters are mapped to appropriate game engine parameters depending on the game engine being used to provide real time processing of the scene. An example mapping for the parameters is provided in Table 4. In some embodiments, a determination is made of whether an enableHighPrecision parameter in the scene description file is true. If it is true, then the physicMaxFrameTime and bounceThreshold parameters are also mapped to the parameters of the appropriate game engine.

[0040] Processing continues with an identification of the collidable nodes (106), which may be based on information provided in the MPEGJnteractivity extension at the scene level. In some embodiments, these nodes are referenced through a nodes array parameter in the collision trigger. In example embodiments, these nodes have the MPEGJnteractivity extension with the usePhysics Boolean to TRUE in the collision trigger.

[0041] The physics parameters are read from the scene description file and mapped to corresponding physics engine parameters (108) for the appropriate node. For each of theexample physics parameters disclosed herein (referred to in Table 4 as “MPEG-I SD” parameters), example parameter mappings are listed for Unity, Unreal, and USD (universal scene description) game engines. It should be understood that the principles described herein are not limited to these specific examples of game engines. The appropriate game engine is launched (110) using the assigned parameter mappings and other information in the scene description file.Table 4.

[0042] In an example method illustrated in FIG. 2, a runtime application obtains a scene description file (202) and reads the value of at least one physics parameter from the file (204). The physics parameter may be, for example, one or more of the parameters provided in Tables 1-3. The runtime application determines the physics engine (206) that will be used to perform the simulation of the scene. A mapping of physics parameters to variables is identified (208) based on the determination of which physics engine will be used. For example, if a PhysX physics engine (the default physics engine of the Unity game engine) is to be used, the mapping may be a mapping of parameters from the first column of Table 4 to variables in the second column of Table 4. If a USD-compatible physics engine is to be used, the mappingmay be a mapping of parameters from the first column of Table 4 to variables in the fourth column of Table 4. Based on the mapping, the value of the at least one physics parameter is assigned (210) to the mapped variable of the physics engine.

[0043] In some embodiments, one or more of the physics parameters in the scene description file may be mapped to variables with different semantics in different physics engines. For example, as noted above, a parameter such as “physicMaxFrameTime” may be used to indicate a maximum time allowed for the physics engine to run in an update loop. In some embodiments, this parameter maps to different variables with different semantics for different physics engines. Some physics engines may allow the setting of a maximum time (or minimum rate) for each iteration of the physics simulation but may allow the use of a lower time (or higher rate), for example if a higher frame rate is used. Other physics engines may only allow for the setting of a fixed iteration time (or fixed rate), which may be equal to or different from the frame rate. In some embodiments, the same physics parameter (e.g. “physicMaxFrameTime”) may be mapped to a maximum iteration time variable in physics engines that use such a variable and to a fixed iteration time variable in other physics engines.

[0044] Some example methods are used in the authoring of scene description files. For example, in the method of FIG. 3, a scene is animated and rendered by a content creator with the use of a physics engine (302) configured with at least one variable. If the scene is satisfactory to the content creator, it may be encoded (304) in a scene description file. A parameter mapping is determined (306) based on the physics engine that was used. For example, if the Unity physics engine was used, the mapping may be a mapping from the variables in the second column of Table 4 to the parameters in the first column of Table 4. If the Unreal physics engine was used, the mapping may be a mapping from the variables in the third column of Table 4 to the parameters in the first column of Table 4. The one or more variables used by the physics engine are assigned (308) to the appropriate parameter indicated by the mapping and encoded (310) in the scene description file.Example Systems

[0045] The encoding, decoding, processing, and rendering of scene descriptions as described herein may be implemented using a system such as the system of FIG. 4. FIG. 4 is a block diagram of an example of a system in which various aspects and embodiments are implemented. System 1000 can be embodied as a device including 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 1000, 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 1000 are distributed across multiple ICs and / or discrete components. In various embodiments, the system 1000 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.

[0046] The system 1000 includes at least one processor 1010 configured to execute instructions loaded therein for implementing, for example, the various aspects described in this document. Processor 1010 can include embedded memory, input output interface, and various other circuitries as known in the art. The system 1000 includes at least one memory 1020 (e.g., a volatile memory device, and / or a non-volatile memory device). System 1000 includes a storage device 1040, 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 1040 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.

[0047] System 1000 includes an encoder / decoder module 1030 configured, for example, to process data to provide an encoded scene or decoded scene, and the encoder / decoder module 1030 can include its own processor and memory. The encoder / decoder module 1030 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 1030 can be implemented as a separate element of system 1000 or can be incorporated within processor 1010 as a combination of hardware and software as known to those skilled in the art.

[0048] Program code to be loaded onto processor 1010 or encoder / decoder 1030 to perform the various aspects described in this document can be stored in storage device 1040 and subsequently loaded onto memory 1020 for execution by processor 1010. In accordance with various embodiments, one or more of processor 1010, memory 1020, storage device 1040, and encoder / decoder module 1030 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 scene, the decoded scene or portions of the decoded scene, thebitstream, matrices, variables, and intermediate or final results from the processing of equations, formulas, operations, and operational logic.

[0049] In some embodiments, memory inside of the processor 1010 and / or the encoder / decoder module 1030 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 1010 or the encoder / decoder module 1030) is used for one or more of these functions. The external memory can be the memory 1020 and / or the storage device 1040, 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 WC (Versatile Video Coding, a new standard being developed by JVET, the Joint Video Experts Team).

[0050] The input to the elements of system 1000 can be provided through various input devices as indicated in block 1130. 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.

[0051] In various embodiments, the input devices of block 1130 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 near-basebandfrequency) 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.

[0052] Additionally, the USB and / or HDMI terminals can include respective interface processors for connecting system 1000 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 1010 as necessary. Similarly, aspects of USB or HDMI interface processing can be implemented within separate interface ICs or within processor 1010 as necessary. The demodulated, error corrected, and demultiplexed stream is provided to various processing elements, including, for example, processor 1010, and encoder / decoder 1030 operating in combination with the memory and storage elements to process the datastream as necessary for presentation on an output device.

[0053] Various elements of system 1000 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 1140, for example, an internal bus as known in the art, including the I nter-IC (I2C) bus, wiring, and printed circuit boards.

[0054] The system 1000 includes communication interface 1050 that enables communication with other devices via communication channel 1060. The communication interface 1050 can include, but is not limited to, a transceiver configured to transmit and to receive data over communication channel 1060. The communication interface 1050 can include, but is not limited to, a modem or network card and the communication channel 1060 can be implemented, for example, within a wired and / or a wireless medium.

[0055] Data is streamed, or otherwise provided, to the system 1000, 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 1060 and the communications interface 1050 which are adapted for Wi-Fi communications. The communications channel 1060 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 1000 using a set-top box that delivers the data over the HDMI connection of the input block 1130. Still other embodiments provide streamed data to the system 1000 using the RF connection of the input block 1130. 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.

[0056] The system 1000 can provide an output signal to various output devices, including a display 1100, speakers 1110, and other peripheral devices 1120. The display 1100 of various embodiments includes one or more of, for example, a touchscreen display, an organic lightemitting diode (OLED) display, a curved display, and / or a foldable display. The display 1100 can be for a television, a tablet, a laptop, a cell phone (mobile phone), or other device. The display 1100 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 1120 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 1120 that provide a function based on the output of the system 1000. For example, a disk player performs the function of playing the output of the system 1000.

[0057] In various embodiments, control signals are communicated between the system 1000 and the display 1100, speakers 1110, or other peripheral devices 1120 using signaling such as AVLink, 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 1070, 1080, and 1090. Alternatively, the output devices can be connected to system 1000 using the communications channel 1060 via the communications interface 1050. The display 1100 and speakers 1110 can be integrated in a single unit with the other components of system 1000 in an electronic device such as, for example, a television. In various embodiments, the display interface 1070 includes a display driver, such as, for example, a timing controller (T Con) chip.

[0058] The display 1100 and speaker 1110 can alternatively be separate from one or more of the other components, for example, if the RF portion of input 1130 is part of a separate set- top box. In various embodiments in which the display 1100 and speakers 1110 are external components, the output signal can be provided via dedicated output connections, including, for example, HDMI ports, USB ports, or COMP outputs.

[0059] The system 1000 may include one or more sensor devices 1095. 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 1000 is used as the control module for an augmented reality display (such as control modules 124, 1254), 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 headmounted 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.

[0060] The embodiments can be carried out by computer software implemented by the processor 1010 or by hardware, or by a combination of hardware and software. As a nonlimiting example, the embodiments can be implemented by one or more integrated circuits. The memory 1020 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 1010 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.Further Embodiments.

[0061] 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.

[0062] 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 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 or decoding scene 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.

[0063] 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.

[0064] 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.

[0065] 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 nonlimiting 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 non-limiting examples.

[0066] 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.

[0067] The implementations and aspects described herein can be implemented in, for example, a method ora 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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, for example, 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.

[0072] It is to be appreciated that the use of any of the following 7”, “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 secondlisted 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.

[0073] 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.

[0074] 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 encoded data 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.

[0075] 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.

[0076] Note that various hardware elements of one or more of the described embodiments may be 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 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.

[0077] Although features and elements are described above in particular combinations, 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 or processor. 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 a scene description file; reading at least one value of a physics parameter from the scene description file; determining a physics engine used by a runtime application; identifying a parameter mapping based on the determined physics engine, wherein the mapping associates physics parameters with physics engine variables; and assigning the value of the physics parameter to a physics engine variable according to the identified mapping.

2. An apparatus comprising one or more processors configured to perform at least: obtaining a scene description file; reading at least one value of a physics parameter from the scene description file; determining a physics engine used by a runtime application; identifying a parameter mapping based on the determined physics engine, wherein the mapping associates physics parameters with physics engine variables; and assigning the value of the physics parameter to a physics engine variable according to the identified mapping.

3. The method of claim 1 or the apparatus of claim 2, wherein the physics parameter is at least one of the following: a gravity parameter, a maximum frame time, a bounce threshold, a collision detection mode, a linear drag coefficient, and / or an angular drag coefficient.

4. The method of claim 1 or claim 3 as it depends from claim 1 , or the apparatus of claim 2 or claim 3 as it depends from claim 2, wherein at least one of the physics parameters is obtained from a scene-level extension in the scene description file.

5. The method of claim 1 or claims 3-4 as they depend from claim 1 , or the apparatus of claim 2 or claims 3-4 as they depend from claim 2, wherein at least one of the physics parameters is obtained from a node-level extension in the scene description file.

6. The method of claim 1 or claims 3-5 as they depend from claim 1 , or the apparatus of claim 2 or claims 3-5 as they depend from claim 2, further comprising reading a flag in the scene description file and determining that the flag is true, wherein at least one of the physicsparameters is obtained from the scene description file only in response to the determination that the flag is true.

7. The method of claim 1 or claims 3-6 as they depend from claim 1 , or the apparatus of claim 2 or claims 3-6 as they depend from claim 2, wherein the parameter mapping is selected from among a plurality of parameter mappings, including a first parameter mapping that maps a first physics parameter to a first physics engine variable and a second mapping that maps the first physics parameter to a second physics engine variable, wherein the first and second physics engine variables have different semantics.

8. The method of claim 7 as it depends from claim 1 , or the apparatus of claim 7 as it depends from claim 2, wherein the first physics engine variable is a maximum interval and the second physics engine variable is a fixed interval.

9. A method comprising: authoring a scene using a physics engine configured with at least one variable; encoding the scene in a scene description file; identifying a parameter mapping based on the physics engine; assigning the variable to a physics parameter based on the mapping; and encoding the physics parameter in the scene description file.

10. An apparatus comprising one or more processors configured to perform at least: authoring a scene using a physics engine configured with at least one variable; encoding the scene in a scene description file; identifying a parameter mapping based on the physics engine; assigning the variable to a physics parameter based on the mapping; and encoding the physics parameter in the scene description file.

11. The method of claim 9, or the apparatus of claim 10, wherein the physics parameter is at least one of the following: a gravity parameter, a maximum frame time, a bounce threshold, a collision detection mode, a linear drag coefficient, and / or an angular drag coefficient.

12. The method of claim 9 or claim 11 as it depends from claim 9, or the apparatus of claim 10 or claim 11 as it depends from claim 10, wherein at least one of the physics parameters is encoded in a scene-level extension in the scene description file.

13. The method of claim 9 or claims 11-12 as they depend from claim 9, or the apparatus of claim 10 or claims 11-12 as they depend from claim 10, wherein at least one of the physics parameters is encoded in a node-level extension in the scene description file.

14. The method of claim 9 or claims 11-13 as they depend from claim 9, or the apparatus of claim 10 or claims 11-13 as they depend from claim 10, further comprising encoding a flag in the scene description file, wherein a value of the flag is based on whether a first one of the physics parameters is encoded in the scene description file.

15. The method of claim 9 or claims 11-14 as they depend from claim 9, or the apparatus of claim 10 or claims 11-14 as they depend from claim 10, wherein the parameter mapping is selected from among a plurality of parameter mappings, including a first parameter mapping that maps a first physics parameter to a first physics engine variable and a second mapping that maps the first physics parameter to a second physics engine variable, wherein the first and second physics engine variables have different semantics.

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