WO2018200337A1

WO2018200337A1 - System and method for simulating light transport between virtual and real objects in mixed reality

Info

Publication number: WO2018200337A1
Application number: PCT/US2018/028638
Authority: WO
Inventors: Tatu V. J. HARVIAINEN
Original assignee: Pcms Holdings, Inc.
Priority date: 2017-04-28
Filing date: 2018-04-20
Publication date: 2018-11-01

Abstract

Systems and methods are disclosed for creating a global lighting solution for augmented reality (AR), virtual reality (VR) and mixed reality (MR) environments. An exemplary method includes determining an environmental lighting model in response to a first content server receiving a content request, an environmental model, and a viewing client pose of a real-world scene. The content server may continuously update lighting impact on the virtual content and virtual lighting effects to objects in the real-world scene that represent the full light transport between real and virtual objects based on (i) dynamic lighting conditions of the real-world scene and/or virtual scene, (ii) the viewing client pose within the real-world scene, and (iii) dynamic elements/objects within the real-world scene and/or virtual scene. The content server may then communicate the updated virtual content to the viewing client device.

Description

SYSTEM AND METHOD FOR SIMULATING LIGHT TRANSPORT BETWEEN VIRTUAL AND REAL

OBJECTS IN MIXED REALITY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a non-provisional filing of, and claims benefit under 35 U.S.C. §119(e) from, U.S. Provisional Patent Application Serial No. 62/491 ,578, filed April 28, 2017, entitled "System and Method for Simulating Light Transport Between Virtual and Real Objects in Mixed Reality," which is incorporated by reference in its entirety.

BACKGROUND

[0002] In mixed reality (MR) use cases where three-dimensional (3D) data, either fully synthetic or captured at a remote location, is be mixed with a view of the real world, one goal for the visual quality is to mix the content elements sufficiently seamlessly that viewers cannot distinguish between elements that are real and those that are virtual.

SUMMARY

[0003] Systems and methods in accordance with some embodiments are disclosed for creating a global lighting solution for augmented reality (AR), virtual reality (VR) and mixed reality (MR) environments. An exemplary method includes determining an environmental lighting model in response to a first content server receiving a content request, an environmental model, and a viewing client pose of a real-world scene. The content server may continuously update lighting impact on the virtual content and virtual lighting effects to objects in the real-world scene that represent the full light transport between real and virtual objects based on (i) dynamic lighting conditions of the real-world scene and/or virtual scene, (ii) the viewing client pose within the real-world scene, and (iii) dynamic elements/objects within the real-world scene and/or virtual scene. The content server may then communicate the updated virtual content to the viewing client device.

[0004] In some embodiments, a method of rendering an MR display may include: receiving, at a content server, environmental model data for a real-world environment of a viewing client; responsive to receiving the environmental model data, determining an environmental lighting model of the viewing client environment using the environmental model data; receiving, at the content server, a content request and a pose of the viewing client in the real-world environment; determining an appearance of a virtual element using the environmental lighting model and the pose; determining a change to a viewing client environment lighting using the virtual element, the environmental lighting model, and the pose; and sending, to the viewing client, the appearance of the virtual element and the change to viewing client environment lighting.

[0005] In some embodiments, the method may further include generating a 3D environmental model from the environmental model data, whereas in alternative embodiments, the environmental model data may already include a 3D environmental model. In some embodiments, the 3D environment model comprises a point cloud, and material definitions of objects in the point cloud may be represented as vertex colors. In some embodiments, the environmental model data comprises RGB-D data. In some

embodiments, a material definition for the virtual element describes at least one selected from the list consisting of: transparency, specular highlights, mirror reflections, and refraction. The appearance of the virtual element and the change to viewing client environment may be sent as compressed data, possibly differential data.

[0006] In some embodiments, the method may further include continuously receiving, at the content server, an updated pose of the viewing client; updating the appearance of the virtual element using the environmental lighting model and the updated pose; updating the change to the viewing client environment using the virtual element, the environmental lighting model, and the updated pose; and sending, to the viewing client, the updated appearance of the virtual element and the updated change to viewing client environment. In some embodiments, the method may further include continuously receiving, at the content server, updated environmental model data for the viewing client environment; and updating the environmental lighting model of the viewing client environment using the updated environmental model data, wherein using the environmental lighting model comprises using the updated environmental lighting model.

[0007] In some embodiments, a method of rendering an MR display may include capturing information about a real-world scene via a set of sensors; responsive to capturing information, creating a 3D reconstruction of the real-world scene; initiating 3D tracking of a current client device pose with respect to the real-world scene; transmitting, to a server: the 3D reconstruction of the real-world scene, and the client device pose; and receiving, from the server: virtual content, updated environment lighting, and lighting textures for existing virtual content. In some embodiments, the method may further include updating the current client device pose; rendering an environment model using the updated current client device pose and a list of geometry indices and vertex color values received from the content server; comparing depth values of each pixel in the environment model to values in the depth map data; and discarding pixels in the environment model having a larger value than the value in the depth map data. [0008] In some embodiments, a system may include a processor; and a non-transitory computer- readable medium storing instructions that are operative, when executed by the processor, to perform the methods disclosed herein. A system my further include a display and a sensor, wherein the sensor may include an RGB-D sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A more detailed understanding may be had from the following description, presented by way of example in conjunction with the accompanying drawings. Furthermore, like reference numerals in the figures indicate like elements.

[0010] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0011] FIG. 1 B is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to some embodiments.

[0012] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1 A according to some embodiments.

[0013] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1A according to some embodiments.

[0014] FIG. 1 E illustrates a network entity that can perform methods disclosed herein, according to some embodiments.

[0015] FIG. 2 illustrates a message flow diagram, according to some embodiments.

[0016] FIG. 3 illustrates a flow chart of an exemplary method that may be used in some embodiments.

[0017] FIG. 4 illustrates a flow chart of another exemplary method that may be used in some embodiments.

[0018] FIG. 5 illustrates a process flow between a client and a server, according to some embodiments.

[0019] FIGs. 6A-6C illustrate a mixed reality (MR) environment display with various modes of rendering, according to some embodiments.

[0020] The entities, connections, arrangements, and the like that are depicted in, and 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 out of 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 some embodiments, ..." For brevity and clarity of presentation, this implied leading clause is not repeated ad nauseum in the detailed description of the drawings.

DETAILED DESCRIPTION

[0021] A detailed description of illustrative embodiments will now be described with reference to the various Figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.

Example networks for implementation of the embodiments.

[0022] FIG. 1A is a diagram illustrating an example system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0023] As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104/113, a CN 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a "station" and/or a "STA", may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things

(loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. By way of example, the client device 102a is depicted as a cellular telephone; the client device

102b is depicted as an HMD for 3D augmented reality (AR), virtual reality (VR) and/or mixed reality (MR) display; client device 102c is depicted as a desktop compute; and the client device 102d is depicted as a tablet computer. Any of WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0024] The communications systems 100 may also include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

[0025] The base station 114a may be part of the RAN 104/113, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

[0026] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0027] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104/113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115/116/117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access (HSUPA).

[0028] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

[0029] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using New Radio (NR).

[0030] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., a eNB and a gNB).

[0031] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0032] The base station 114b in FIG. 1 A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106/115. [0033] The RAN 104/113 may be in communication with the CN 106/115, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or the CN 106/115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113, which may be utilizing a NR radio technology, the CN 106/115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0034] The CN 106/115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or the other networks 112. The PSTN 108 may include circuit- switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common

communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and/or the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104/113 or a different RAT.

[0035] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1 A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0036] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a

speaker/microphone 124, a keypad 126, a display/touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and/or other peripherals 138, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment. [0037] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0038] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0039] Although the transmit/receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more

transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0040] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0041] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0042] The processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0043] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location- determination method while remaining consistent with an embodiment.

[0044] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, an Augmented Reality, Virtual Reality, and/or Mixed Reality (AR/VR/MR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and/or a humidity sensor.

[0045] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and/or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0046] FIG. 1 C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0047] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a.

[0048] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0049] The CN 106 shown in FIG. 1 C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0050] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and/or WCDMA.

[0051] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter- eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0052] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0053] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0054] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network. In representative embodiments, the other network 112 may be a WLAN.

[0055] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and/or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad- hoc" mode of communication.

[0056] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0057] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0058] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0059] Sub 1 GHz modes of operation are supported by 802.11af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11 ah relative to those used in 802.11 n, and 802.11 ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non- TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type

Control/Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0060] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 η, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes. Carrier sensing and/or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0061] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0062] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0063] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and/or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180c).

[0064] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and/or OFDM subcarrier spacing may vary for different transmissions, different cells, and/or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and/or lasting varying lengths of absolute time).

[0065] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and/or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with/connect to gNBs 180a, 180b, 180c while also communicating with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and/or throughput for servicing WTRUs 102a, 102b, 102c.

[0066] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0067] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0068] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and/or the like. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP access technologies such as WiFi.

[0069] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet- based, and the like.

[0070] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet- switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0071] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0072] FIG. 1 E depicts an exemplary network entity 190 that may be used in embodiments of the present disclosure, for example as a content server or as a WTRU. As depicted in FIG. 1 E, network entity 190 includes a communication interface 192, a processor 194, and non-transitory data storage 196, all of which are communicatively linked by a bus, network, or other communication path 198.

[0073] Communication interface 192 may include one or more wired communication interfaces and/or one or more wireless-communication interfaces. With respect to wired communication, communication interface 192 may include one or more interfaces such as Ethernet interfaces, as an example. With respect to wireless communication, communication interface 192 may include components such as one or more antennae, one or more transceivers/chipsets designed and configured for one or more types of wireless (e.g., LTE) communication, and/or any other components deemed suitable by those of skill in the relevant art. And further with respect to wireless communication, communication interface 192 may be equipped at a scale and with a configuration appropriate for acting on the network side— as opposed to the client side— of wireless communications (e.g., LTE communications, Wi-Fi communications, and the like). Thus, communication interface 192 may include the appropriate equipment and circuitry (perhaps including multiple transceivers) for serving multiple mobile stations, UEs, or other access terminals in a coverage area.

[0074] Processor 194 may include one or more processors of any type deemed suitable by those of skill in the relevant art, some examples including a general-purpose microprocessor, a graphics processing unit (GPU) and a dedicated digital signal processor (DSP). Data storage 196 may take the form of any non- transitory computer-readable medium or combination of such media, some examples including flash memory, read-only memory (ROM), and random-access memory (RAM) to name but a few, as any one or more types of non-transitory data storage deemed suitable by those of skill in the relevant art could be used. As depicted in FIG. 1 E, data storage 196 is a non-transitory computer-readable media that contains program instructions 197 executable by processor 194 for carrying out various combinations of the various network-entity functions described herein. Processor 194 is configured to execute instructions 197 stored in memory 196.

[0075] In view of Figures 1 A-1 E, and the corresponding description of Figures 1 A-1 E, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions. By way of example, the client device 102a is depicted as a cellular telephone; the client device 102b is depicted as an HMD for 3D AR, VR and/or MR display; client device 102c is depicted as a desktop compute; and the client device 102d is depicted as a tablet computer. It should be understood that any of these devices, or other devices having similar functionality may be suitable for either the client side device or the server side device.

Lighting model determination.

[0076] Systems and methods in accordance with some embodiments are disclosed for creating a global lighting solution for AR, VR and MR environments. An exemplary method includes determining an environmental lighting model in response to a first content server receiving a content request, an environmental model, and a viewing client pose of a real-world scene. The content server may continuously update lighting impact on the virtual content and virtual lighting effects to objects in the real-world scene that represent the full light transport between real and virtual objects based on (i) dynamic lighting conditions of the real-world scene and/or virtual scene, (ii) the viewing client pose within the real-world scene, and (iii) dynamic elements/objects within the real-world scene and/or virtual scene. The content server may then communicate the updated virtual content to the viewing client device.

[0077] In mixed reality (MR) use cases where three-dimensional (3D) data, either fully synthetic or captured at a remote location, is be mixed with a view of the real world, one goal for the visual quality is to mix the content elements sufficiently seamlessly that viewers cannot distinguish between elements that are real and those that are virtual. For such seamless mixing of virtual and real elements, light transport may have a noticeable impact on the result. To seamlessly embed virtual elements with real elements, the lighting that makes the elements visible is ideally identical for both virtual and real elements. Further, a system may also take into an account how the light would bounce among virtual and real objects, as if they really were physically present in the same space, by simulating the behavior of the light in a physically plausible manner.

[0078] Simulation of lighting for virtual content has been one of the areas of research in the field of computer graphics for many decades, resulting in a wide array of different methods for simulating different aspects of light and geometry interaction. Traditional approaches in real-time computer graphics complying with the limited graphics processing resources includes handling different aspects of the lighting separately, for example by simulating shading of the surfaces and shadows cast by the objects separately. However, approaches that simulate the full light transport in the 3D scene may produce a global illumination of 3D scenes that is more physically plausible by simulating shading, shadows and color bleeding caused by the light bouncing between all elements in the 3D scene. Such global illumination methods are currently suitable also for real-time use, but only on most up to date state of the art graphics hardware.

[0079] Some early MR systems addressed light transport between virtual and real elements by simulating light transport taking place from the virtual elements to the real environment or vice versa, but not both simultaneously. Alternatively, cumbersome external camera set-ups were often required.

Furthermore, common rendering methods for producing global illumination effects tended to have high performance cost, and were thus not suitable for execution on MR HMDs that had limited graphics processing performance. Some earlier solutions further failed to support dynamic scenes that included both real and virtual objects. [0080] Some embodiments described herein address simulation of light transport between virtual and real elements in AR, VR, and MR use cases, focusing on enabling even devices with limited graphics processing power to display advanced lighting effects through use of distributed rendering between, e.g., a content server and a viewing client. For simplicity, this disclosure will make reference to MR and example MR use cases; however, it should be understood that the techniques described herein may be applied or extended, with or without modification as appropriate, to AR and/or VR use cases. Described herein are example methods and systems according to some embodiments for creating a global lighting solution for an MR scene including determining an environmental lighting model in response to a first content server receiving a content request, an environmental model, and a viewing client pose of a real-world scene; continuously updating the lighting impact on the virtual content and virtual lighting effects to objects in the real-world scene that represent the full light transport between real and virtual objects, and communicating the updated virtual content to the viewing client. The updates may be based on dynamic lighting conditions of the real-world scene and/or virtual scene, the viewing client pose within the real-world scene, and, e.g., dynamic elements or dynamic objects within the real-world scene and/or virtual scene.

[0081] Some embodiments described herein may also describe simulation of light transport by a distributed rendering approach where a client device provides a content server with information about the physical environment and the server simulates the actual light transport and transmits the results back to the client along with the 3D assets of the virtual elements. Such embodiments may use 3D reconstruction of the environment as a way of transporting information about the physical environment from the client to the server. Such embodiments may also or alternatively use the structure of the 3D reconstruction to efficiently transmit the results of the light transport simulation back to the client from the server. A rendering process at the client device occurs, as described below, or similarly. As the 3D reconstruction is known by both the client and the server when the light transport simulation has been executed, the amount of data used to transmit back to the client may be reduced in order to minimize bandwidth burdens.

[0082] In some embodiments, an initialization phase includes launching a viewer client for execution on an MR HMD. The client begins 3D reconstruction of the physical environment and 3D tracking of the device pose relative to the environment. The client sends 3D reconstruction and pose information to the content server along with a content request, and the content server detects or extracts an environment lighting model based on the received 3D reconstruction. The content server retrieves requested content and aligns it relative to the 3D reconstruction. Subsequently, a run-time process may begin as, e.g., described below.

[0083] In some embodiments, the run-time process includes the client sending current 3D tracking pose information (relative to the environment 3D reconstruction) to the content server. The content server updates content elements, combines them with the 3D reconstruction received from the client, and executes light simulation that results in a list of vertex indexes and changes in the per-vertex colors resulting from the light simulation. Based on the current pose of the client device, the content server sends the list of vertex indexes and values that have a changed value (due to the lighting simulation that are visible to the viewer) as a result of the current client pose. The content server modifies assets of the virtual content, so that they contain the simulated lighting, and sends the assets/updates to the client. The client receives the list of vertex indexes together with change values and virtual content elements. The client may render virtual content elements and 3D reconstruction geometry in areas where per-vertex values changed (using change values received from the content server) from the point of view determined by the 3D tracking pose.

[0084] FIG. 2 illustrates a message flow diagram 200, according to some embodiments. As illustrated, FIG. 2 includes a user 205, an AR/VR/MR viewer client device 210 (e.g., MR viewer client device 210 which may be a WTRU, such as TRU 102b, as described in FIGs. 1 A-1 E), an AR/VR/MR content server 215 (e.g., MR content server 215), and an AR/VR/MR content storage database 220 (e.g., MR content storage database 220). Initially, a use session is initiated 225 by user 205, who requests the client 210 to display MR content. At the beginning of the use session, during a "Reconstruct Environment" phase (in some embodiments), user 205 starts up client device (MR viewer client) 210. MR viewer client 210 scans and reconstructs 230 a 3D model of the environment, and notifies 235 user 205 that client device 210 is ready.

[0085] In some embodiments, MR device 210, used for viewing the content, is embedded with sensors for capturing depth information in the user's 205 environment. A sensor, or a combination of sensors, may include one or more of RGB-D cameras, stereo cameras combined with depth from stereo processing, Lidar (light detection and ranging), or any other technique for capture of depth information. When the viewing session is initialized by the user 205, viewing client 210 reconstructs the environment model by collecting depth data from the environment. During reconstruction 230, the process executed on viewer client device 210 collects point cloud data from the environment as user 205 moves the device and sensors in the environment. Sensor observations with varying points of view may be combined to form a coherent 3D reconstruction of the environment (e.g., the complete environment) that user 205 is in. 3D

reconstruction of the environment may be carried out with any reconstruction method as applicable, such as methods used in conjunction with KinectFusion or Point Cloud Library (PCL).

[0086] In some embodiments, the requested MR content to be displayed includes a link 240 to MR content server 215 and a reference to the specific MR content to be displayed. The link may be embedded with an application that is configured to receive content links, such as a web browser or a social media client. In some embodiments, when link 240 is activated by user 205, MR client 210 begins an initialize session phase. As an example alternative, in some embodiments, the user activating link 240 is the action that triggers scanning and 3D reconstruction 230 of the environment.

[0087] In some embodiments, MR client 210 is further configured to perform a pose-tracking process 245. In some embodiments, at least one result of pose tracking 245 is an estimate of the location of MR viewing client device 210, and its orientation relative to the reconstructed environment. Pose tracking may be performed using any tracking technique as applicable and may be assisted by using the reconstructed environment model. In message process 250, client 210 sends the reconstructed environment model to server 215 along with the pose and a request for specific MR content. In some embodiments, the 3D reconstruction should reach a sufficient level of completeness before the client device 210 proceeds to send the reconstructed model to the content server 215. The level of completeness may be measured, for example, as the percentage of the surrounding area coverage, amount of observations, or any other similar quality value that can be used as a threshold.

[0088] Collected environment data may also be used by client device 210 during the session to assist device pose tracking. Pose, e.g., location and orientation, of client device 210 may be used for registering the augmented elements to the physical environment, e.g., in synch with user 205 head movements. The 3D model is sent to content server 215, via message process 250, so that content server 215 can be utilized to attempt to optimize content delivery. Further, pose information is sent to the content server 215 to allow the content server 215 to estimate visibility of virtual elements from the user's viewpoint, in relation with the physical elements in the environment, e.g., as described below.

[0089] Once content server 215 receives an MR content request from client 210, content server 215 may determine (e.g., solve for (or calculate) or otherwise retrieve or receive) an environment lighting model 255 based on the received 3D reconstruction of the client environment. In some embodiments, a method used for capturing, solving, or calculating the environment lighting model may be any available method that produces a description of the directions and intensities of the light sources based on the 3D reconstruction of the environment provided by client 210. Examples of lighting model capture methods and rendering methods that may be used in exemplary embodiments include those that may be known in the art, for example a method described in KRONANDER, Joel, et al. "Photorealistic rendering of mixed reality scenes," Computer Graphics Forum, 2015. p. 643-665.

[0090] Content server 215 fetches 260 the requested content from content storage 220, and the runtime processing phase begins. The run-time processing phase may be a continuous (ongoing) phase, in which at least one result is continuous output of visual images of the physical environment augmented with virtual elements at a sufficient frame rate for motion of the visual elements to appear to be continuous (without flickering). In practice, this may require, for example, that the content rendering rate at the client device 210 exceed 15 frames per second (fps), but other rates may be used. In addition to the frame rate, latency of the rendering may also have an impact on the quality of the experience on the MR use cases.

[0091] As used herein, in accordance with some embodiments, latency is the time required to update visual output on the display of client 210, based on head motion of user 205. Latency caused by the network communication may sometimes prevent content server 215 from performing a full rendering when, e.g., content server 215 is updated on user 205 motion at a slow latency. For at least this reason, in some embodiments, content server 215 may only assist with real-time rendering performed on the client device 210. This may be accomplished by performing the lighting simulation in a manner that enables fast viewpoint updates on the client side.

[0092] As illustrated in FIG. 2, the run-time processing phase may include client device 210 sending a current pose 265 of client device 210 to content server 215. Content server 215 updates and places the content into the environment model and simulates lighting 270. The content, simulated lighting, and changes in appearance of the environment caused by light interaction with embedded elements is sent 275 to client device 210, which displays 280 the content and changes in the environment to user 205. This process produces a global illumination model based on a 3D reconstruction and is suitable for distributed execution (distributed rendering) by server 215 and client 210.

[0093] Flowcharts in FIGs. 3 and 4 illustrate a more detailed flow of the example run-time process, for some embodiments, at both the client side (FIG. 3) and the content server side (FIG. 4) and may be viewed with reference to FIG. 2. FIG. 3 illustrates a flow chart of an exemplary method 300 for a process executed by a client device, such as MR viewer client device 210, that may be used in some embodiments.

[0094] As illustrated, method 300 includes initiating 302 the run-time process. The current pose is sent 304 to a content server, such as MR content server 215. In response to a change in pose, new 3D assets may be received 306. A check 308 is made to determine whether new assets have been received. If so, the new assets are uploaded 310 to a processing unit, such as a GPU. Otherwise, if there are no new assets received, method 300 proceeds directly to receiving 312 updated environment lighting (if any). If updated environment lighting is determined 314 to have been received, the received data is stored 316 for use in rendering. Otherwise, if no updated environment lighting is received, method 300 proceeds to receiving 318 updated lighting textures for the 3D assets (if any). If it is determined 320 that updated lighting textures are received, then the textures are uploaded 322 to the GPU.

[0095] Then, according to the example, a depth map is captured 324, using an RGB-D sensor, for example. The current pose is updated 326, and the environment model is rendered 328 using the current pose and list of geometry indices and vertex values received from content server 215. In some

embodiments, for each pixel, the depth value may be compared with the depth map captured by the RGB- D sensor. If the depth map has a smaller value than the associated pixel, the pixel may be discarded. Subsequently, virtual elements may be rendered 330 using the current pose, object geometry, object textures, and lighting textures. In some embodiments, for each pixel, the depth value is compared with the corresponding depth map value, as captured by the RGB-D (or other) sensor, and discarded if the depth map has a smaller value. If a signal to terminate the run-time process has been received 332, then the runtime process is terminated 334. Alternatively, the process repeats by sending 304 a current pose (in this part of the example process, an updated pose) to the content server 215. Method 300 may iterate, for some embodiments, from sending 304 updates through rendering 330 based on received updates, while waiting for a termination request to be received 332.

[0096] FIG. 4 illustrates a flow chart of an exemplary method 400 for a process executed by a content server, such as MR content server 215, that may be used in some embodiments. As illustrated, method 400 begins upon initiation 402 of the run-time process. The current pose is received 404 from a client, such as MR viewer client device 210. The server then updates 406 the virtual content. If no new assets are added 408 to the scene, method 400 continues to detect 410 whether there are any changes in the generated virtual content. If there are no changes, method 400 moves back to receiving 404 the current pose from client device 210. If new assets were added 408 to the scene, content server 215 creates 414 texture coordinates for use by the lighting texture for the additional assets (e.g., objects). The new assets are sent 416 to the client device 210, and the assets are combined 418 with the 3D reconstruction of the physical environment.

[0097] The example method proceeds to executing 412 a lighting simulation for estimating global illumination using the environment lighting model and the combined scene. In some embodiments, content server 215 performs the light transport simulation by combining virtual elements together with the 3D reconstruction of the environment received from client device 210, using the lighting models constructed from the 3D reconstruction of the environment prior to initiation of the run-time process. In some embodiments, the light transport simulation performed by content server 215 may produce a global illumination that matches from a physically plausible simulation of photons being emitted by light sources in the scene bouncing off from different surfaces. In some embodiments, surfaces in the simulation include both virtual elements and real-world elements captured by the 3D reconstruction process.

[0098] For some embodiments, in the light transport simulation, only the viewpoint independent diffuse term of the indirect lighting may be calculated for the 3D reconstruction representing the real-world. For the 3D reconstruction, the materials of the individual elements captured in the 3D reconstruction may be unknown, and the only variation to the lighting of the real-world environment that may be simulated is caused by light bouncing off from, or being blocked by, the virtual elements. Materials may be known for the virtual elements, and thus, viewpoint-dependent aspects of the lighting, such as specular terms of the surface shading, may be simulated. For light transport simulation, suitable methods, many examples of which are known in the art, may be used.

[0099] For example, light transport simulation for part of 3D reconstruction may be executed, in some embodiments, with a differential rendering approach so that only the differences caused by the embedding of virtual elements are considered. For the 3D reconstruction of the environment, only changes (detected in 410) in indirect lighting and shadows cast by the virtual elements are considered per vertex basis on the 3D reconstruction geometry, for some embodiments. For the virtual elements, content server 215 may form the materials and lighting into a single texture or may create a separate lighting texture that is then streamed to client device 210.

[0100] As method 400 proceeds, content server 215 renders 420 the asset lighting to a lighting texture using the current pose, the global illumination estimate, the environment lighting model, and the material definitions of the asset. Content server 215 may then optimize and compress 424 environment lighting data using environment lighting data stored 422 in the cache and the current pose. Subsequently, content server 215 may optimize and compress 428 lighting textures using the current pose and previous asset lighting textures stored 426 in the cache.

[0101] To perform data transmission efficiently, content server 215 optimizes and compresses 424/428 the data prior to transmission 432. In some embodiments, one step in the optimization processes may be visibility detection. Since content server 215 has information on the viewpoint location of the viewer (user 205) within the 3D reconstruction of the geometry, content server 215 can discard per vertex variation values that are not visible to user 205 due to occlusions caused by the environment elements or virtual elements closer to the viewer. Discarding of occluded values may be performed with a margin that includes vertex change values so that slight viewpoint changes may be performed while still having most or all change values available for most or all visible vertices.

[0102] In some embodiments, the discard margin may be used to allow client device 210 to change viewpoints according to the most up-to-date 3D tracking pose while rendering, so that the latency between the 3D tracking and visual registration is minimized. After verifying the visibility of the vertices, in some embodiments, the next step of data optimization may be thresholding of the change values. In the thresholding, vertices with change values below a threshold level deemed observable to the viewer may be discarded.

[0103] Changes in the environment lighting caused by the virtual elements may be, in some or most cases, temporally highly redundant, and changes in consecutive time steps may be relatively small. Due to this temporal redundancy, content server 215 may efficiently compress the optimized simulation results. The current environment, lighting data, and lighting textures are stored 430 in the cache for use in a subsequent iteration of processes 424 and 428. That is, to compress the data, content server 215 caches 430 previously optimized simulation results and uses a combination of spatial compression and temporal motion compensation, similar to compression methods used with video encoding. By doing so, content server 215 only transmits visually observable changes in vertex values from the previously sent data. After compression, the compressed data is sent 432 to the client.

[0104] In some embodiments described herein, virtual content is considered to include synthetic 3D assets, e.g. 3D geometry produced by 3D artist, and/or real-time or offline created full 3D scans of a real physical objects. In the case of fully synthetic 3D assets and offline scanned 3D objects, content server 215 may send assets only once to client device 210, in some embodiments. It should be understood, however, that some embodiments may employ refresh stages where data is resent to ensure that both remote modules are operating on equivalent models. Thus in some embodiments, during run-time, only updates to the lighting are streamed to client device 210 in most transmissions. When the 3D assets are sent to client device 210, content server 215 may also produce per-object unwrap texture coordinates that may be used to map lighting textures created by content server 215 to the object. During run-time, content server 215 may simulate the effect of the lighting on the surface of the object and store the result as a lighting texture. Lighting textures may be optimized and compressed 428 similar to the environment light simulation results. For example, parts of the lighting texture unobservable to the viewer may be discarded, and for the remaining data, only observable changes with respect to the previously sent and cached result are compressed with spatial-temporal compression. Optimized and compressed lighting textures are then streamed 432 to the client.

[0105] For real-time 3D captured content in some embodiments, several lighting textures may be created. Real-time captured 3D content may not have a static geometry, but rather, the geometry of the object changes for each captured time step, and textures may be re-mapped to each time step of the capture. However, the re-mapped texture coordinates may be used to replace the original texture with versions of textures that integrate both texturing/material and the lighting.

[0106] In some embodiments, lighting simulation for the virtual elements includes, e.g., most or all lighting effects that are possible to simulate with the material definitions provided for the virtual elements. For virtual elements with material definitions describing transparency, viewpoint dependent aspects such as specular highlights, mirror reflections, and refraction may also be included. Viewpoint dependent lighting may be simulated using the known client viewpoint provided by client 210, and based on the 3D tracking. There may be latency between the visual output of the viewpoint dependent lighting from the head motion of user 205, due to the time needed to process the content at the content server 215 side and any network communication latency. However, since this latency primarily impacts the viewpoint dependent lighting, while virtual element registration is based during rendering on the most up-to-date pose, visual artifacts caused by the latency are smaller than the benefit of rendering high quality lighting on virtual elements.

[0107] After the light transport simulation has been executed, a list of 3D reconstruction vertex indexes and change in the vertex color values are known for vertices that have changed color value due to the light transport caused by the virtual elements. In order for client device 210 to reproduce the change in lighting, the data including vertex indices and per vertex color values is transmitted 432 to the client 210. If a signal has been received 434 to terminate the run-time process, the run-time process terminates 436.

Alternatively, method 400 iterates by continuously receiving 404 an updated (current) pose from the client device 210 and then updating the data items sent to the client.

[0108] In some embodiments, during the run-time process, client 210 receives changed vertex values for the 3D reconstruction and virtual elements/lighting of the virtual elements. In some embodiments, when rendering, client 210 uses the most up-to-date pose provided by the 3D tracking to minimize the visual latency between user 205 head motions and visual feedback. Client 210 also captures depth values from the RGB-D (or Lidar, or other) sensor to correctly handle occlusions between dynamic objects and rendering of the content received from content server 215.

[0109] In some embodiments, the 3D reconstruction format of the environment includes a dense triangulated point cloud, with material definitions in a format of vertex colors. With point cloud data, the shape of the geometry is defined with a large number of 3D points, defined as x, y, z coordinate values. A point in the point cloud often corresponds with a depth sensor sampling result when the data originates from a real world 3D capture. In addition to the 3D location of each point in a point cloud, additional information can be included per point basis, such as color value, unit vector normal etc. In such an embodiment, an RGB value may be used for each vertex. In some other embodiments, the environment 3D reconstruction includes vertices having texture coordinates and a 2D image texture containing the diffuse colors. In such embodiments, the light simulation results may be mapped to the 3D reconstruction textures, rather than on vertices of the actual geometry. In such embodiments, the optimization and compression are then executed on the textures that are produced with a differential rendering approach.

[0110] In some embodiments, the overall structure may be organized so that during the initialization phase of the run-time process, client 210 performs a 3D reconstruction and transmits the reconstruction to the content server 215. The 3D reconstruction is then used throughout the session. In some other embodiments, client 210 continuously updates the 3D reconstruction and re-transmits updated 3D reconstructions to the content server 215 in response to detecting sufficiently large changes to warrant a refresh or retransmission. In such embodiments, client 210 may maintain a cached copy of the 3D reconstruction for rendering use, while simultaneously maintaining the actively updated version of the 3D reconstruction when applicable.

[0111] In some embodiments, client 210 does not create the 3D reconstruction, but rather streams RGB- D data to the content server 215, which may then create the 3D reconstruction and transmit the 3D reconstruction to client 210 for use as a geometric model when rendering the changes in the environment lighting appearance. In some embodiments, client 210 renders changes in the environment lighting and the virtual elements, using the advanced lighting model data provided by content server 215. In some other embodiments, the rendering is distributed such that content server 215 only provides changes in the diffuse lighting, such as providing only the effect of the global illumination as if materials were matte (Lambertian reflectance) and only providing changes for the virtual elements. In such embodiments, client 210 may receive material definitions from content server 215 for the virtual elements and may render the viewpoint- dependent aspects of the lighting locally. Such embodiments reduce latency that may be introduced from the viewpoint-dependent aspects of the lighting, but may demand more graphics processing at client device 210.

[0112] In some embodiments, graphics are output on an MR HMD. In some embodiments, the MR HMD may be a near-the-eye light-field display. In such embodiments, content server 215 may produce the full Hogel-rendering according to the viewpoint provided to content server 215 by the 3D tracking of client 210. The Hogel-rendering may produce an image array complying with the micro-lens array used by the light- field display. A light-field display allows user 205 to dynamically adjust the viewpoint. In some

embodiments, the Hogel-rendering executed by content server 215 is expanded, so that the anticipated range of head motions between content processing frames is covered. This may allow the rendering at the client side to update the viewpoint according to the most up-to-date tracking pose, thereby reducing the latency otherwise caused by the server-side network communication and processing.

[0113] In some embodiments, client device 210 is an optical see-through MR HMD with a light blocking layer and may reproduce reduction of light values from the environment, in addition to adding light. In such an example, the MR HMD may reproduce shadows cast by virtual objects in the environment. In some embodiments, the MR HMD is an optical see-through display, having a light-emitting display without a selectively blocking layer, and thus not usable for removing light from the environment. In such

embodiments, content server 215 or client device 210 may perform post processing on the produced differential rendering to detect high frequency lighting value changes to darker values, such as sharp shadow edges. The human visual system is typically more prone to detecting clear contrast changes than detecting gradual changes in tone, and embodiments herein may introduce changes in contrast by increasing the light of areas around sharp shadows. This results in having a sharp light value change at the location of a shadow edge, while gradually fading the light increase, that is used to enable a sharp edge, away from the edge area.

[0114] Some embodiments compose virtual elements together with a view of the real-world. The dynamic range of the display may not match the range of human perception. In some embodiments, characteristics of the human visual system may be used during the run-time process for calibration of the display system and tone mapping on the rendering/output process. Such embodiments may consider the impact of light addition and light removal from the real-world view, as well as the dynamic range comparison between virtual and real-world elements, in order to ensure that the final view composition of real-world view and content output with the MR HMD produces desired end results: an acceptable use experience. If such tone mapping is included with the rendering process, the run-time process executed by client 210 may be modified so that, in addition to the RGB-D sensor depth map, an RGB camera image showing the view of user 205 is also captured. The RGB camera image may be captured using a high dynamic range approach capturing several images with different shutter values. The captured RGB images of the view may be used for detecting the current illumination levels seen by user 205 from the physical environment. They may also be used to map the RGB values received from server 215 to tone and opacity values that produce desired output for an optical see-through display, or when composited with another type of display.

[0115] FIG. 5 illustrates an example process flow 500a between a client 500b and a server 500c during an MR session, according to some embodiments. Client 500b may be similar to MR viewer client device 210 (of FIG. 2), and may be a WTRU, such as TRU 102b. Server 500c may be similar to MR content server 215 (of FIG. 2) or network entity 190 (of FIG. 1 E). In describing FIG. 5, an example scenario will be used that describes a particular example embodiment. In the example scenario, a user is in a room, viewing a virtual object augmented in the center of the room. The client device simulates light transfer between virtual and physical elements and displays the results on an optical see-through MR HMD worn by the user. Processes and steps performed by the solution, from initialization to the output, and observation by the viewer of the final rendering, are illustrated and described.

[0116] For better understanding, the example process flow 500a of FIG. 5 should be viewed with the following example annotations in place for the abbreviated text tags adjacent to each numbered element:

501 At the start of a session, user scans the physical environment by inspecting it from several different viewpoints.

502 Client reconstructs 3D model of the physical environment from the collected data. Here 2D map is used for representing the reconstructed 3D model of the physical environment. 503 Content server receives 3D reconstruction of the environment from the client together with the current viewer location in relation with the 3D reconstruction and content request content.

504 Content server executes environment lighting model reconstruction to estimate main light sources in the scene.

505 Content server merges virtual content elements with the 3D reconstruction of the environment.

506 Content server creates unwrapping texture coordinates to be used by the lighting textures for the content elements and sends 3D assets, textures and lighting texture unwrapping coordinates to the client.

507 Client receives 3D assets (e.g., Geometry, textures and lighting map texture coordinates) of the virtual content.

508 Content server updates virtual elements and executes light transport simulation on the merged 3D reconstruction and virtual elements using reconstructed environment lighting model.

509 Differential rendering isolates vertices that have their color value changed due to the light transport simulation.

510 Parts of the light transport simulation result not observable from the proximity of the current viewpoint are removed.

511 Server compresses light transport simulation result by comparing it with the previous result stored in the cache and using spatial compression. Compressed data is sent to the client. New result is stored to the cache.

512 Client receives changed per vertex lighting values for the 3D reconstruction of the environment.

513 Virtual elements are rendered with the full lighting simulation according to the element materials thus producing also viewpoint dependent lighting effects.

514 Results of the differential rendering are rendered as a texture using lighting texture coordinates created in the initialization phase.

515 Parts of the result not observable from the proximity of the current viewpoint are removed.

516 Optimized texture is compressed with spatio-temporal approach based on the cached previous result and sent to the client. Current texture is stored to the cache.

517 Client receives changed per vertex lighting values for the 3D reconstruction of the environment.

518 Client requests depth data from the RGB-D sensor and up-to-date pose from the 3D tracking.

519 Client renders environment lighting according to the received environment lighting values using the geometry created in the environment 3D reconstruction. Parts occluded by the dynamic objects detected from the RGB-D depth data are not rendered.

520 Client renders virtual elements, adding effect of lighting simulation from the received lighting texture. Parts occluded by dynamic objects detected from the RGB-D depth data are not rendered.

521 Final view for the viewer looking at the environment through optical see-through AR/MR HMD. 561 Light sources as detected by the environment lighting model reconstruction executed by the server.

562 Current viewpoint sent by the client.

563 Color bleed caused by the light bouncing from virtual element to the chair.

564 Color bleed caused by the elements in environment and light reflectance on the virtual element.

565 Shadow cast by the virtual element to the environment model.

[0117] As illustrated, FIG. 5 includes the user scanning 501 , at the start of a session, a physical environment by inspecting the environment from different viewpoints. As illustrated, the room contains a chair. The client device reconstructs 502 a 3D model of the physical environment from the collected data. For ease of description and presentation, in some places 2D maps and perspectives are shown in FIG. 5. Along with the content request, the content server receives 503 the 3D reconstruction of the environment from the client, which is illustrated as model 560a. The content server executes 504 environment lighting model reconstruction to estimate light sources in the scene. That is, light sources are detected 561 from the received environmental data, and the current viewer location (pose) 562 is also received from the client. The content server merges 505 virtual content elements (a star-shaped cylinder is used in this example) with the 3D reconstruction of the environment. As illustrated, a star-shaped cylinder (the virtual object) is placed (virtually) nearby a chair. The merged 3D reconstruction 560b now contains the real-world objects, plus the virtual element (virtual object). The content server then creates 506 unwrapping texture coordinates for use by the lighting textures for the content elements and sends 3D assets, textures, and lighting texture unwrapping coordinates to the client.

[0118] The client receives 507 the 3D assets, which may include geometry, textures, and lighting map texture coordinates of virtual content elements/objects. On the content server side, the content server updates 508 virtual elements and executes light transport simulation on the merged 3D reconstruction and virtual elements using a reconstructed environment lighting model. This may include color bleed 563 from the virtual element onto real-world objects in the room, such as a chair, color bleed 564 from real-world elements onto virtual elements, and shadows 565 cast by virtual element onto real-world objects. The 3D reconstruction 560c now shows interactions among real-world objects and virtual elements, which include virtual objects and lighting and shadowing effects.

[0119] In some embodiments, a differential rendering 509 isolates vertices that have a color value that has changed, due to light transport simulation. Parts of the light transport simulation that are not observable from the proximity of the current pose may be removed 510. The content server compresses 511 the light transportation simulation results by comparing the simulation to the previous simulation stored in the cache. Further, the content server may perform spatial compression on the simulation results. The compressed data is sent to the client, and the new result is stored in the cache for later use. The client receives 512 the changes per vertex lighting values formed by the comparison of the lighting simulation results for the 3D reconstruction of the environment. Back at the content server, at 513, virtual elements are rendered by the server with full lighting simulation, according to the element materials, producing viewpoint-dependent lighting effects. The results of the differential rendering are rendered 514 as a texture using lighting texture coordinates created in the initialization phase. Parts of the differential rendering that are not observable from the proximity of the current viewpoint are removed 515. The optimized texture is compressed 516 using a spatial-temporal approach based on the stored texture and sent to the client. The current texture is then stored in the cache for future use.

[0120] The client then receives 517 the changed per-vertex lighting values for the 3D reconstruction of the environment and requests 518 depth data from an RGB-D sensor and an updated pose from the 3D tracking system. The client renders 519 the environment lighting according to the received environment lighting values using the geometry created in the environment 3D reconstruction. According to the example processing, any detected occluded portions are not rendered. The client renders 520 the virtual elements, adding lighting effects from the received lighting texture. Again, occluded parts are not rendered. At 521 , FIG. 5 shows both the objects rendered on the display (Output on Display 550) of the MR HMD as well as the final view 551 seen by the viewer through the optical see-through MR HMD.

[0121] FIGs. 6A-6C illustrate a mixed reality (MR) environment display with various modes of rendering, according to some embodiments. FIG. 6A illustrates a first rendering 600a. Rendering 600a includes real- world objects, such as a flat-sided glass jar 601, a statue 602, and a hand 603 grabbing a ball 604.

Rendering 600a also includes virtual elements, such as a framed picture 611 held by a hand 613, and a simulated bright spot 612 from a virtual light source. Note that bright spot 612 has a triangular concavity 612a, which is a shadow caused by virtual framed picture 611.

[0122] FIG. 6B illustrates another rendering 600b. Rendering 600b includes lighting interactions between real-world objects 601-604, and virtual elements 611 and 613. As illustrated, a flat side of glass jar 601 shows a simulated reflection 621 of virtual elements framed picture 611 and hand 613. Because virtual framed picture 611 is identified as having a glossy, reflective covering (such as a glass pane over the picture, it shows a simulated reflection of real-world objects statue 602, hand 603, and ball 604. However, this is only a first-order interaction between real-world and virtual elements (such that, e.g., the simulated reflection of the real-world objects 602, 603, 604 are not themselves rendered in the simulated reflection 621 of virtual elements framed picture 611 and hand 613).

[0123] FIG. 6C illustrates yet another rendering 600c. Rendering 600c includes a further order of interactions between real-world objects and virtual elements. A simulated reflection 622 of virtual framed picture 611 , on the nearby flat side of glass jar 601 , now includes the simulated reflection of real-world objects statue 602, hand 603, and ball 604 from virtual framed picture 611. That is, the simulation of reflections illustrated in FIG. 6C includes multi-bounce reflections. In general, the methods taught herein can handle multiple reflection interactions among real-world and virtual elements (as well as among multiple virtual elements). The number of reflection steps processed for a rendering may be limited by the time budgeted for rendering each frame for a user. Alternatively, or in conjunction with resource- constrained limitations on multi-bounce calculations, a threshold for the size, intensity, or other factor affecting human perception may be compared with a threshold, and a particular multi-bounce rendering will reach only as far as the threshold.

Exemplary applications.

[0124] Some embodiments described herein allow advanced lighting to be simulated on the content server when delivering MR scenes in a manner that takes into account light transport both ways from the virtual elements to the real elements and vice versa. Some embodiments disclosed herein leverage the possibility to harness high processing power of the server with a data transfer approach that reduces an amount of data transferred, so that even MR HMDs with limited graphics processing power and data transfer rates may display MR scenes with photorealistic lighting effects accommodating local lighting of the physical environment.

[0125] Some embodiments described herein include simulation and display of lighting effects that virtual elements would cause if they were physically present in the environment in which they are augmented. Some embodiments are based on client-server architecture, where a client can be an MR HMD device with limited graphics processing performance. A content server simulates lighting interaction between virtual and physical elements with advanced lighting simulation algorithms. Furthermore, in accordance with some embodiments, communication between the content server and the client device may be based on indexing environment geometry of the 3D reconstruction of the environment, which is shared information for both the client device and the content server, thus leading to an efficient communication structure as only changes in the environment shading may need to be transmitted with indexed geometry pointing to areas to be updated.

[0126] In some embodiments, a method of rendering an MR display may include: receiving, at a content server, environmental model data for a real-world environment of a viewing client; responsive to receiving the environmental model data, determining an environmental lighting model of the viewing client environment using the environmental model data; receiving, at the content server, a content request and a pose of the viewing client in the real-world environment; determining an appearance of a virtual element using the environmental lighting model and the pose; determining a change to a viewing client environment lighting using the virtual element, the environmental lighting model, and the pose; and sending, to the viewing client, the appearance of the virtual element and the change to viewing client environment lighting.

[0127] In some embodiments, the method may further include generating a 3D environmental model from the environmental model data, whereas in alternative embodiments, the environmental model data may already include a 3D environmental model. In some embodiments, the 3D environment model comprises a point cloud, and material definitions of objects in the point cloud may be represented as vertex colors. In some embodiments, the environmental model data comprises RGB-D data. In some

[0128] In some embodiments, the method may further include continuously receiving, at the content server, an updated pose of the viewing client; updating the appearance of the virtual element using the environmental lighting model and the updated pose; updating the change to the viewing client environment using the virtual element, the environmental lighting model, and the updated pose; and sending, to the viewing client, the updated appearance of the virtual element and the updated change to viewing client environment. In some embodiments, the method may further include continuously receiving, at the content server, updated environmental model data for the viewing client environment; and updating the environmental lighting model of the viewing client environment using the updated environmental model data, wherein using the environmental lighting model comprises using the updated environmental lighting model.

[0129] In some embodiments, a method of rendering an MR display may include capturing information about a real-world scene via a set of sensors; responsive to capturing information, creating a 3D reconstruction of the real-world scene; initiating 3D tracking of a current client device pose with respect to the real-world scene; transmitting, to a server: the 3D reconstruction of the real-world scene, and the client device pose; and receiving, from the server: virtual content, updated environment lighting, and lighting textures for existing virtual content. In some embodiments, the method may further include updating the current client device pose; rendering an environment model using the updated current client device pose and a list of geometry indices and vertex color values received from the content server; comparing depth values of each pixel in the environment model to values in the depth map data; and discarding pixels in the environment model having a larger value than the value in the depth map data.

[0130] In some embodiments, a system may include a processor; and a non-transitory computer- readable medium storing instructions that are operative, when executed by the processor, to perform the methods disclosed herein. A system my further include a display and a sensor, wherein the sensor may include an RGB-D sensor.

[0131] According to some embodiments, a system includes a processor; and a non-transitory computer- readable medium storing instructions that are operative, when executed by the processor, to perform the methods described herein.

[0132] In some embodiments, a system and method for creating a global lighting solution for a mixed reality scene includes determining an environmental lighting model in response to a first content server receiving a content request, an environmental model, and a viewing client pose of a real-world scene. The content server may continuously update lighting impact on the virtual content and virtual lighting effects to objects in the real-world scene that represent the full light transport between real and virtual objects based on (i) dynamic lighting conditions of the real-world scene and/or virtual scene, (ii) the viewing client pose within the real-world scene, and (iii) dynamic elements/object within the real-world scene and/or virtual scene. The content server then communicates the updated virtual content to the viewing client device.

[0133] In some embodiments, a system and method for creating a global lighting solution includes capturing, at a first client device, real-world scene information via sensors and initiates creation of a 3D reconstruction of a real-world scene. The client further initiates 3D tracking of a pose of the first client device relative to the real-world scene. The first client device transmits the 3D reconstruction of the real- world scene and the pose of the first client device to the content server along with a content request.

[0134] In response to receipt of the 3D reconstruction of a real-world scene and the content request, the content server detects the environment lighting model from the 3D reconstruction of a real-world scene and retrieves requested content and aligns it relative to the 3D reconstruction and the pose of the first client device. In a continuous manner, the client device sends the current pose of the first client device with respect to the real-world scene (3D reconstruction of the real-world scene) to the content server. The content server updates the content elements including virtual objects and combines the updated content elements with the 3D reconstruction received from the client. The content server executes a light simulation to generate a list of vertex indexes and change in the per vertex colors resulting from the light simulation. Based on the current pose of the client device, the content server sends the list of vertex indexes and values that have a changed value that are visible to the viewer from the current pose of the client device.

[0135] The content server modifies the lighting of the content elements so that they contain the simulated lighting and either sends the results/updates to the client device. The client device receives the list of vertex indexes together with change values and content elements and renders the received virtual content elements and lighting effects in areas where per vertex values changed using the values received from the content server from the point of view determined by the pose of the client device. [0136] In some embodiments, a system for creating a global lighting solution may include a first client device for capturing real-world scene information via sensors disposed on the client device, the client device initiating a creation of a 3D reconstruction of a real-world scene and initiating 3D tracking of the first client device pose relative to the real-world scene. The first client device sends the 3D reconstruction of a real-world scene and first client device pose to the first content server along with a first content request. In response to receipt of the 3D reconstruction of a real-world scene and the first content request, the content server may detect the environment lighting model from the 3D reconstruction of a real-world scene, retrieve the requested content and align the requested content relative to the 3D reconstruction and the first client device pose. In a continuous manner, the client device sends a current pose of the client device relative to the real-world scene (or the 3D reconstruction of the real-world scene to the content server. The content server may update content elements (e.g., virtual objects) and combine them with the 3D reconstruction received from the client device. The content server may execute light simulations resulting in a list of vertex indexes and change in the per-vertex colors resulting from the light simulation. Based on the current pose of the first client device, the content server sends list of vertex indexes and values that have a changed value due to the lighting simulation that are visible to the viewer from the pose of the client device. The content server may modify the lighting of the content elements so that they contain the simulated lighting and the content server sends the result and/or updates to the client device. The client device receives the list of vertex indexes, the change values, and content elements and responsively renders the received virtual content elements and lighting effects in areas where per-vertex values changed using the values received from the server from the point of view determined by the pose of the client device.

[0137] 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.

[0138] 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 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

CLAIMS What is Claimed:

1. A method of rendering a mixed reality (MR) display, the method comprising:

receiving, at a content server, environmental model data for a real-world environment of a viewing client;

responsive to receiving the environmental model data, determining an environmental lighting model of the viewing client environment using the environmental model data;

receiving, at the content server, a content request and a pose of the viewing client in the real-world environment;

determining an appearance of a virtual element using the environmental lighting model and the pose;

determining a change to a viewing client environment lighting using the virtual element, the environmental lighting model, and the pose; and

sending, to the viewing client, the appearance of the virtual element and the change to the viewing client environment lighting.

2. The method of claim 1 wherein the environmental model data comprises a 3D environmental model.

3. The method of claim 1 further comprising:

generating a 3D environmental model from the environmental model data.

4. The method of claim 2 or 3 wherein the 3D environment model comprises a point cloud.

5. The method of claim 4 wherein material definitions of objects in the point cloud are represented as vertex colors.

6. The method of claim 1 wherein the environmental model data comprises RGB-D data.

7. The method of claim 1 wherein a material definition for the virtual element describes at least one selected from the list consisting of:

transparency, specular highlights, mirror reflections, and refraction.

8. The method of claim 1 wherein sending, to the viewing client, the appearance of the virtual element and the change to the viewing client environment lighting comprises sending compressed data.

9. The method of claim 8 wherein the compressed data comprises differential data.

10. The method of claim 1 further comprising:

continuously receiving, at the content server, an updated pose of the viewing client;

updating the appearance of the virtual element using the environmental lighting model and the updated pose;

updating the change to the viewing client environment lighting using the virtual element, the environmental lighting model, and the updated pose; and

sending, to the viewing client, the updated appearance of the virtual element and the updated change to viewing client environment lighting.

11. The method of claim 10 further comprising:

continuously receiving, at the content server, updated environmental model data for the viewing client environment; and

updating the environmental lighting model of the viewing client environment using the updated environmental model data, wherein using the environmental lighting model comprises using the updated environmental lighting model.

12. A system comprising:

a processor; and

a non-transitory computer-readable medium storing instructions that are operative, when executed by the processor, to perform the method of any of clams 1 through 11.

13. A method of rendering a mixed reality (MR) display, the method comprising:

capturing information about a real-world scene via a set of sensors;

responsive to capturing information, creating a 3D reconstruction of the real-world scene;

initiating 3D tracking of a current client device pose with respect to the real-world scene;

transmitting, to a content server:

the 3D reconstruction of the real-world scene, and

the current client device pose; and

receiving, from the content server:

virtual content,

updated environment lighting, and

lighting textures for the virtual content.

14. The method of claim 13, further comprising:

updating the current client device pose;

rendering an environment model using the updated current client device pose and a list of geometry indices and vertex color values received from the content server;

comparing depth values of each pixel in the environment model to corresponding values in a depth map; and

discarding pixels in the environment model having a larger depth value than the corresponding value in the depth map.

15. A system comprising:

a display;

a sensor;

a processor; and

a non-transitory computer-readable medium storing instructions that are operative, when executed by the processor, to perform the method of any of clams 13 or 14.

16. The system of claim 15 wherein the sensor comprises an RGB-D sensor.