Patent Publication Number: US-10769849-B2

Title: Use of temporal motion vectors for 3D reconstruction

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/250,827, filed on Nov. 4, 2015, the entire content of which is herein incorporated by reference. 
    
    
     BACKGROUND 
     With the advent of virtual or augmented reality technologies (e.g., real-time immersive virtual reality or teleportation), there is a large demand for three-dimensional (3D) content creation and streaming to users to enable immersive experiences. Providing immersive experiences for live sporting events or performances may entail capturing large dynamic scenes and constructing 3D representations of the captured spaces for broadcast or streaming. 3D representation or rendering of such large dynamic scenes may be quite expensive in terms of computing, network, and display resources. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example computing system (including cloud computing component) configured to use temporal motion vectors for 3D reconstruction of sparse voxels for displaying of dynamic scenes, according to an embodiment of the present disclosure. 
         FIG. 2  is a block diagram of an example 3D reconstruction system, according to another embodiment of the present disclosure. 
         FIG. 3  is a flowchart illustrating an example method for 3D reconstruction, according to an embodiment of the present disclosure. 
         FIG. 4  illustrates an example system platform to perform 3D reconstruction, according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Further to the issues discussed above, in some possible techniques for addressing these concerns, some of the computing tasks can be offloaded to cloud computing resources. Such resources may provide for free viewpoint or interactive experiences, but require full geometry of the scene to be streamed and rendered on a client device (display client) using a voxel representation. This significantly increases computing at the display client. In other possible techniques, sparse voxel octree (SVO) representations can be used to limit the computational cost during rendering. For example, only pixels to be displayed are computed. This limits the amount of 3D voxel data (and thus, storage space) required for realistic, high-resolution digital models or environments. However, this type of optimization is primarily geared towards static scenes, and does not optimize well for real-time large dynamic scenes such as sports broadcasts. 
     Thus, techniques for efficiently 3D rendering dynamic scenes are disclosed. According to some embodiments of the present disclosure, the techniques include reconstructing and streaming sparse voxels for dynamic scenes. These embodiments reduce data bandwidth requirements and reduce display resource utilization for displaying dynamic scenes compared to other possible techniques, such as those discussed above. According to some such embodiments, the temporal motion of objects in dynamic scenes is learned such that only the part of the sparse voxel representation that undergoes changes in time is reconstructed or streamed. This reduces the data bandwidth requirement. Further, only having to render part of the scene reduces display resource utilization. This provides for improved user experiences in applications such as real-time immersive virtual reality or teleportation, including 3D broadcasts of live events like sportscasts. 
     According to some embodiments, the disclosed techniques are implemented on a computing system or a graphics processing system, or a software product executable or otherwise controllable by such systems. The system or product is configured to receive image/depth data from multiple cameras, fuse the multi-sensor data into 3D voxel data, identify the sparse subset of voxel data observable from the viewer&#39;s perspective, and broadcast or otherwise stream this sparse subset of voxel data to a display device of the user. In some such embodiments, some or all of the image processing takes place using cloud computing resources. 
       FIG. 1  illustrates an example computing system  100  (including cloud computing component  110 ) configured to use temporal motion vectors for 3D reconstruction of sparse voxels for displaying of dynamic scenes, according to an embodiment of the present disclosure. The 3D reconstruction system  100  includes a data capture circuit  102  configured to capture image or depth data from multiple cameras  104  or other image sensors. The cloud computing component  110  includes a 3D processing pipeline circuit  120 . The 3D processing pipeline circuit  120  includes an image processing circuit  122 , a voxel selection circuit  124 , a temporal adjustment circuit  126 , and a voxel output circuit  128 . 
     The 3D reconstruction system  100  further includes a temporal motion vector circuit  130  to determine those objects in the scene undergoing change (e.g., movement) and those objects that are not changing (e.g., static). In addition, the 3D reconstruction system  100  includes a display device (or display client)  140  for presentation of the processed image data to a user. For example, the display device may be a 3D display device or a 2D display device configured to display the 3D scene from a desired or particular perspective. While the 3D reconstruction system  100  of  FIG. 1  is described as a collection of distinct circuits and devices, the present disclosure is not limited thereto, and in other embodiments, some of the circuits or their functions may be combined or split among still further circuits. 
     The image processing circuit  122  processes the image or depth data from the multiple cameras  104  as assembled and output by the data capture circuit  102 . For example, in some embodiments, the image processing circuit  122  orders the image data samples by time (e.g., in frames) and fuses (e.g., by volumetric fusion) the image data from the different sensors into corresponding voxel (3D) data. The voxel selection circuit  124  reduces the voxel data into a sparse data set, such as those voxels viewable to the user from the user&#39;s perspective, including such fields as color, normal, and texture. This data set may be, for example, a sparse voxel octree (SVO) data set. The temporal adjustment circuit  126  further processes the sparse voxel data set, removing those entries associated with stationary (e.g., nonchanging) objects. To this end, the temporal adjustment circuit  126  uses output data from the temporal motion vector circuit  130  (e.g., identification of static voxels) to produce a sparse set of changed voxels (or temporal delta from the previous set of voxel data output). The voxel output circuit  128  broadcasts or otherwise streams this processed sparse subset (or dynamic sparse subset) of voxel data to a display device  140  of the user, such as an SVO ray cast display device or display client, for presentation to the user. In some embodiments, the display client  140  interprets the dynamic sparse subset to be the only voxels capable of changing from the previous frame; all other voxels being either not currently viewable or associated with static objects (and thus rendered the same as in the previous frame). 
     According to an embodiment, the sparse voxels are generated in pipeline fashion after volumetric fusion of the scenes from multiple sensor imagery. By way of example, the image processing circuit  122 , the voxel selection circuit  124 , the temporal adjustment circuit  126 , and the voxel output circuit  128  may each process in parallel on a different subset of the image data received from the cameras  104 . According to some embodiments, the voxel selection circuit  124  reduces the potentially huge amount of storage space needed to store all of the voxel data by using an SVO implementation to store the 3D data, but only storing voxel data that contributes to the final observable image to the user (for example, not storing voxel data for inner voxels or occluded voxels). In addition, unlike other possible techniques, according to some embodiments, this voxel selection undergoes further reduction (e.g., in the temporal adjustment circuit  126 ) for dynamic scenes by not including voxel data for static elements of the scene. Other possible techniques, by contrast, process dynamic scenes by processing and generating voxel data for all scene geometry (dynamic and static) each frame. 
     According to some embodiments of the present disclosure, temporal motion of objects in dynamic scenes is accounted for, and only those voxels undergoing change are reconstructed or streamed as part of the output sparse voxel representation. This reduces the data bandwidth needed to process the 3D data and reduces display resources needed to display the data. In an embodiment, the SVO tree is reconstructed by learning which objects (and their corresponding voxels) change temporally in the scene and filtering out those voxels that are part of static objects. This reduces the scene geometry size to be streamed between frames, thus reducing or optimizing the bandwidth needed for real-time broadcast 3D data formats of dynamic scenes such as sportscasts. According to some such embodiments, the display client renders the voxels corresponding to the static objects the same as it did in the previous frame. 
     With further reference to  FIG. 1 , according to some embodiments, Sparse Voxel Octree (SVO) representations of the display of 3D dynamic scenes are made temporally efficient by using a temporal motion vector circuit  130  to learn objects in the dynamic scene that are changing temporally and to reconstruct only the voxels that change with each frame. This is as opposed to reconstructing the entire scene or portions of the dynamic scene that are static from frame to frame, as performed by other possible techniques. 
     To identify objects&#39; motion over time, in some embodiments, object segmentation is used on captured images. For example, in one embodiment, an object segmentation circuit  132  learns the objects and their segmentation or separation using existing machine learning algorithms. Further, in some embodiments, a motion detection circuit  134  identifies those objects that change between frames. A voxel mapping circuit  136  maps objects to voxels of the volumetric scene representation of the 3D image data. A static voxel filtering circuit  138  identifies and, possibly in conjunction with the temporal adjustment circuit  126 , filters out the static voxels from the 3D pipeline. This results in an SVO that is further tuned with temporal voxel information, which dramatically reduces the size of the output voxel data for network streaming. 
     The embodiments described herein provide for improved 3D reconstruction of dynamic scenes by using temporal motion vectors. The disclosed embodiments may be implemented on a broad range of computing and communication platforms, including mobile devices, since the disclosed techniques are computationally efficient. These embodiments may further be implemented in hardware or software or a combination thereof. 
     With further reference to  FIG. 1 , in embodiments of the present disclosure, the cameras  104  may be any sensor (e.g., 2D, 3D, infrared, radar) capable of providing image data. The cameras  104  are spatially separated. For example, in one embodiment, the cameras  104  are positioned about a scene at regular (or roughly regular) intervals (or vantage points) to provide 3D coverage of the scene through their overlapping coverage areas. This coverage is sufficient to permit 3D reconstruction of the scene from any viewing point. 
     The cameras  104  provide time-based samples of their field of view to the data capture circuit  102 . The data capture circuit  102  collects these image data samples and provides them (e.g., in time order) to the 3D processing pipeline circuit  120 . In addition, the image data is provided to the temporal motion vector circuit  130  to perform the temporal motion processing. In one embodiment, as illustrated in  FIG. 1 , the temporal motion processing includes the object segmentation circuit  132 , which receives the image data from the data capture circuit  102  and performs object semantic segmentation on the image data. Here, the image data is segmented into objects. With object segmentation, the motion detection circuit  134  may track motion (and other visual change) of these objects temporally between frames. The voxel mapping circuit  136  maps the volumetric representation of each object to corresponding voxels, each object having its own volumetric voxel representation. This helps to keep track of temporal information specific to each object. 
     In an embodiment, the static voxel filtering circuit  138  determines, for each object, if there is no visually-impacting change detected in the object temporally. If so, the object&#39;s voxels are updated (or marked, such as in a temporal delta field) as inactive. Likewise, voxels of objects that have changed are marked active by the static voxel filtering circuit  138 . In an embodiment, the voxel mapping circuit  136  maps all of the voxels for each object in an entire 3D scene. In some embodiments, the temporal adjustment circuit  126  filters out voxels from the full scene volumetric fusion that have been marked as inactive by the static voxel filtering circuit  138 , which reduces the SVO size dramatically. This helps to reduce the network bandwidth required for dynamic scenes as only temporally optimized SVOs are streamed to the display device  140 . 
       FIG. 2  is a block diagram of an example 3D reconstruction system  200 , according to another embodiment of the present disclosure. The 3D reconstruction system  200  reconstructs a dynamic scene as a set of voxels and includes a data capture circuit  202 , an image processing circuit  204 , a voxel selection circuit  206 , an object segmentation circuit  212 , a motion detection circuit  214 , a voxel mapping circuit  216 , a static filter circuit  218 , and a voxel output circuit  220 . This embodiment is like the embodiment shown in  FIG. 1  in that it includes parallel processing as shown. Thus, the previous relevant discussion is equally applicable here, however, in the embodiment of  FIG. 2 , note that the temporal adjustment circuit  126  of  FIG. 1  has been integrated into the static filter circuit  218 . 
     The data capture circuit  202  is configured to receive image data from each of two or more spatially-separated sensors observing the scene from a corresponding two or more vantage points. The sensors may be cameras or other visual sensing devices. The sensors are spatially separated (from different vantage points) in a sense that they are sufficiently far apart to permit 3D reconstruction of the scene by combining (or fusing) their corresponding image signals. For example, the sensors may surround or encompass the scene, and may be equidistant (or roughly equidistant) from their nearest neighboring sensors. The image processing circuit  204  is configured to fuse the image data from the different sensors into the set of voxels (3D representation) on a frame-by-frame basis. This may be accomplished, for example, by volumetric fusion or other techniques of fusing overlapping 2D image data into 3D data. The voxel selection circuit  206  is configured to select only those voxels currently visible to a user of the display device, to produce a sparse subset of the voxels, such as a sparse voxel octree (SVO) representation of the voxels. 
     The object segmentation circuit  212  is configured to segment the image data into objects that constitute the scene (e.g., by using machine learning algorithms). The motion detection circuit  214  is configured to detect which of the objects remain static (e.g., do not change) from frame to frame. The remaining objects in the scene are dynamic (e.g., moving or otherwise changing). The voxel mapping circuit  216  is configured to map the static objects to their corresponding voxels. The static filter circuit  218  is configured to filter the sparse subset to remove those voxels corresponding to the static objects, to produce a dynamic subset of the sparse subset (e.g., a dynamic sparse subset of the voxels). The voxel output circuit  220  is configured to output (to a display device) those voxels corresponding to the dynamic objects and not to the static objects. The voxel output circuit  220  is further configured to only output those of the voxels belonging to the dynamic sparse subset. In some embodiments, the display device is configured to receive the voxels corresponding to the dynamic objects, render the received voxels corresponding to the dynamic objects, and render voxels corresponding to the static objects received during earlier frames. 
     Methodology 
       FIG. 3  is a flowchart illustrating an example method  300  for 3D reconstruction of a dynamic scene as a set of voxels, according to an embodiment of the present disclosure. As may be seen, example method  300  includes several phases and sub-processes, the sequence of which may vary from one embodiment to another. However, when considered in the aggregate, these phases and sub-processes form a process for 3D reconstruction in accordance with some of the embodiments disclosed herein. These embodiments may be implemented, for example, using one of the system architectures illustrated in  FIG. 1  and  FIG. 2  as described above. 
     However, other system architectures may be used in other embodiments, as will be apparent in light of this disclosure. To this end, the correlation of the various functions shown in  FIG. 3  to the specific components illustrated in the other figures is not intended to imply any structural or use limitations. Rather, other embodiments may include, for example, varying degrees of integration where multiple functionalities are effectively performed by one system. For example, in an alternative embodiment, a single module may be used to perform all the functions of method  300 . Thus, other embodiments may have fewer or more modules or sub-modules depending on the granularity of implementation. In still other embodiments, the methodology depicted may be implemented as a computer program product including one or more non-transitory machine readable mediums that when executed by one or more processors cause the methodology to be carried out. Numerous variations and alternative configurations will be apparent in light of this disclosure. 
     As illustrated in  FIG. 3 , in one embodiment, method  300  for 3D reconstruction commences by receiving, at operation  310 , image data from each of two or more spatially-separated sensors observing the scene from a corresponding two or more vantage points. This may be performed, for example, by the data capture circuit  202  of  FIG. 2 . At operation  320 , the image data is fused into the set of voxels on a frame-by-frame basis. This may be performed, for example, by the image processing circuit  204  of  FIG. 2 . At operation  330 , only those voxels currently visible to a user of the display device are selected to produce a sparse subset of the voxels. These voxels may be organized, for example, in a sparse voxel octree (SVO) format. This operation may be performed, for example, by the voxel selection circuit  206  of  FIG. 2 . 
     At operation  340 , the image data is segmented into objects that constitute the scene. This may be performed, for example, by the object segmentation circuit  212  of  FIG. 2 . At operation  350 , the objects that remain static from frame to frame are detected. The remaining objects are dynamic (e.g., move or otherwise change between frames). This may be performed, for example, by the motion detection circuit  214  of  FIG. 2 . At operation  360 , the static objects are mapped to their corresponding voxels. This may be performed, for example, by the voxel mapping circuit  216  of  FIG. 2 . At step  370 , the sparse subset is filtered to remove those voxels corresponding to the static objects, to produce a dynamic subset of the sparse subset. This may be performed, for example, by the static filter circuit  218  of  FIG. 2 . At step  380 , those voxels corresponding to the dynamic objects (and not to the static objects) are output to a display device (such as a 3D display device or an SVO ray cast display device). This may entail only outputting those voxels belonging to the dynamic sparse subset of voxels. This may be performed, for example, by the voxel output circuit  220  of  FIG. 2 . 
     In some embodiments, the method further includes receiving, by the display device, the voxels corresponding to the dynamic objects; rendering, by the display device, the received voxels corresponding to the dynamic objects; and rendering, by the display device, voxels corresponding to the static objects received during earlier frames. In some embodiments, additional operations may be performed, as previously described in connection with the system. 
     Example System 
       FIG. 4  illustrates an example system  400  to perform 3D reconstruction, according to an embodiment of the present disclosure. In some embodiments, system  400  includes a platform  410  that may host, or otherwise be incorporated into, a personal computer, workstation, laptop computer, ultra-laptop computer, tablet, touchpad, portable computer, handheld computer, palmtop computer, personal digital assistant (PDA), cellular telephone, combination cellular telephone and PDA, smart device (for example, smartphone or smart tablet), mobile internet device (MID), messaging device, data communication device, television (TV), smart TV, TV receiver/converter or set top box, and so forth. Any combination of different devices may be used in some embodiments. 
     In some embodiments, platform  410  may include any combination of a processor  420 , memory  430 , 3D reconstruction system  200 , network interface  440 , input/output (I/O) system  450 , imaging sensors  104 , display device  140 , user interface  460 , and storage system  470 . As may be further seen, a bus or interconnect  492  is also provided to allow for communication between the various components listed above or other components not shown. Platform  410  may be coupled to a network  494  through network interface  440  to allow for communications with other computing devices, platforms, or resources. Other componentry and functionality not reflected in the block diagram of  FIG. 4  will be apparent in light of this disclosure, and it will be appreciated that other embodiments are not limited to any particular hardware configuration. 
     Processor  420  may be any suitable processor, and may include one or more coprocessors or controllers, such as an audio processor or a graphics processing unit, to assist in control and processing operations associated with system  400 . In some embodiments, the processor  420  may be implemented as any number of processor cores. The processor (or processor cores) may be any type of processor, such as, for example, a micro-processor, an embedded processor, a digital signal processor (DSP), a graphics processor (GPU), a network processor, a field programmable gate array, or other device configured to execute code. The processors may be multithreaded cores in that they may include more than one hardware thread context (or “logical processor”) per core. Processor  420  may be implemented as a complex instruction set computer (CISC) or a reduced instruction set computer (RISC) processor. In some embodiments, processor  420  may be configured as an ×86 instruction set compatible processor. 
     In some embodiments, the disclosed techniques for 3D reconstruction may be implemented in a parallel fashion, where tasks may be distributed across multiple CPU/GPU cores or other cloud based resources to enable real-time processing from image capture to display. 
     Memory  430  may be implemented using any suitable type of digital storage including, for example, flash memory or random access memory (RAM). In some embodiments, the memory  430  may include various layers of memory hierarchy or memory caches. Memory  430  may be implemented as a volatile memory device such as, but not limited to, a RAM, dynamic RAM (DRAM), or static RAM (SRAM) device. Storage system  470  may be implemented as a non-volatile storage device such as, but not limited to, one or more of a hard disk drive (HDD), a solid state drive (SSD), a universal serial bus (USB) drive, an optical disk drive, a tape drive, an internal storage device, an attached storage device, flash memory, battery backed-up synchronous DRAM (SDRAM), and a network accessible storage device. In some embodiments, storage  470  may include technology to increase the storage performance enhanced protection for valuable digital media when multiple hard drives are included. 
     Processor  420  may be configured to execute an Operating System (OS)  480  that may include any suitable operating system, such as Google Android (Google Inc., Mountain View, Calif.), Microsoft Windows (Microsoft Corp., Redmond, Wash.), Apple OS X (Apple Inc., Cupertino, Calif.), or Linux. As will be appreciated in light of this disclosure, the techniques provided herein may be implemented without regard to the particular operating system provided in conjunction with system  400 , and therefore may also be implemented using any suitable existing or subsequently-developed platform. 
     Network interface circuit  440  may be any appropriate network chip or chipset which allows for wired or wireless connection between other components of computer system  400  or network  494 , thereby enabling system  400  to communicate with other local or remote computing systems, servers, and cloud-based servers or resources. Wired communication may conform to existing (or yet to be developed) standards, such as, for example, Ethernet. Wireless communication may conform to existing (or yet to be developed) standards, such as, for example, cellular communications including LTE (Long Term Evolution), Wireless Fidelity (Wi-Fi), Bluetooth, or Near Field Communication (NFC). Example wireless networks include, but are not limited to, wireless local area networks, wireless personal area networks, wireless metropolitan area networks, cellular networks, and satellite networks. 
     I/O system  450  may be configured to interface between various I/O devices and other components of computer system  400 . I/O devices may include, but not be limited to, imaging sensors  104 , display device  140 , user interface  460 , and other devices not shown such as a keyboard, mouse, microphone, and speaker, etc. 
     It will be appreciated that in some embodiments, the various components of the system  400  may be combined or integrated in a system-on-a-chip (SoC) architecture. In some embodiments, the components may be hardware components, firmware components, software components, or any suitable combination of hardware, firmware, or software. 
     3D reconstruction system  200  is configured to provide three-dimensional (3D) reconstruction of a dynamic scene as a set of voxels. These techniques include receiving image data from each of two or more spatially-separated sensors observing the scene from a corresponding two or more vantage points and fusing the image data into the set of voxels on a frame-by-frame basis. These techniques further include segmenting the image data into objects that constitute the scene and detecting which of the objects remain static from frame to frame, the remaining objects being dynamic. Further, these techniques include outputting those voxels corresponding to the dynamic objects and not to the static objects. 3D reconstruction system  200  may include any or all of the components illustrated in  FIGS. 1-3 , as described above. 
     3D reconstruction system  200  may be implemented or otherwise used in conjunction with a variety of suitable software or hardware that is coupled to or that otherwise forms a part of platform  410 . 3D reconstruction system  200  may additionally or alternatively be implemented or otherwise used in conjunction with user I/O devices that may provide information to, and receiving information and commands from, a user. These I/O devices may include devices collectively referred to as user interface  460 . In some embodiments, user interface  460  may include a textual input device such as a keyboard, and a pointer-based input device such as a mouse. Other input/output devices that may be used in other embodiments include a touchscreen, a touchpad, a microphone, and a speaker. Still other input/output devices may be used in other embodiments. Further examples of user input may include gesture or motion recognition and facial tracking. 
     In some embodiments, 3D reconstruction system  200  may be installed local to system  400 , as shown in the example embodiment of  FIG. 4 . In other embodiments, system  400  may be implemented in a client-server arrangement where at least some functionality associated with these circuits is provided to system  400  using an applet, such as a JavaScript applet, or another downloadable module. Such a remotely accessible module or sub-module may be provisioned in real-time, in response to a request from a client computing system for access to a given server having resources that are of interest to the user of the client computing system. In such embodiments, the server may be local to network  494  or remotely coupled to network  494  by one or more other networks or communication channels. In some cases, access to resources on a given network or computing system may require credentials such as usernames, passwords, or compliance with any other suitable security mechanism. 
     In various embodiments, system  400  may be implemented as a wireless system, a wired system, or a combination of both. When implemented as a wireless system, system  400  may include components and interfaces suitable for communicating over a wireless shared media, such as one or more antennae, transmitters, receivers, transceivers, amplifiers, filters, control logic, and so forth. An example of wireless shared media may include portions of a wireless spectrum, such as the radio frequency spectrum and so forth. When implemented as a wired system, system  400  may include components and interfaces suitable for communicating over wired communications media, such as input/output adapters, physical connectors to connect the input/output adaptor with a corresponding wired communications medium, a network interface card (NIC), disc controller, video controller, audio controller, and so forth. Examples of wired communications media may include a wire, cable metal leads, printed circuit board (PCB), backplane, switch fabric, semiconductor material, twisted pair wire, coaxial cable, fiber optics, and so forth. 
     Various embodiments may be implemented using hardware elements, software elements, or a combination of both. Examples of hardware elements may include processors, microprocessors, circuits, circuit elements (for example, transistors, resistors, capacitors, inductors, and so forth), integrated circuits, ASICs, programmable logic devices, digital signal processors, FPGAs, logic gates, registers, semiconductor devices, chips, microchips, chipsets, and so forth. Examples of software may include software components, programs, applications, computer programs, application programs, system programs, machine programs, operating system software, middleware, firmware, software modules, routines, subroutines, functions, methods, procedures, software interfaces, application program interfaces, instruction sets, computing code, computer code, code segments, computer code segments, words, values, symbols, or any combination thereof. Determining whether an embodiment is implemented using hardware elements or software elements may vary in accordance with any number of factors, such as desired computational rate, power level, heat tolerances, processing cycle budget, input data rates, output data rates, memory resources, data bus speeds, and other design or performance constraints. 
     Some embodiments may be described using the expression “coupled” and “connected” along with their derivatives. These terms are not intended as synonyms for each other. For example, some embodiments may be described using the terms “connected” or “coupled” to indicate that two or more elements are in direct physical or electrical contact with each other. The term “coupled,” however, may also mean that two or more elements are not in direct contact with each other, yet still cooperate or interact with each other. 
     The various embodiments disclosed herein may be implemented in various forms of hardware, software, firmware, or special purpose processors. For example, in one embodiment at least one non-transitory computer readable storage medium has instructions encoded thereon that, when executed by one or more processors, cause one or more of the 3D reconstruction methodologies disclosed herein to be implemented. The instructions may be encoded using a suitable programming language, such as C, C++, object oriented C, Java, JavaScript, Visual Basic .NET, Beginner&#39;s All-Purpose Symbolic Instruction Code (BASIC), or alternatively, using custom or proprietary instruction sets. The instructions may be provided in the form of one or more computer software applications or applets that are tangibly embodied on a memory device, and that may be executed by a computer having any suitable architecture. 
     In one embodiment, the system may be hosted on a given website and implemented, for example, using JavaScript or another suitable browser-based technology. For instance, in some embodiments, the system may leverage processing resources provided by a remote computer system accessible via network  494 . In other embodiments, the functionalities disclosed herein may be incorporated into other software applications, such as virtual reality applications, gaming applications, entertainment applications, or other video processing applications. 
     The computer software applications disclosed herein may include any number of different modules, sub-modules, or other components of distinct functionality, and may provide information to, or receive information from, still other components. These modules may be used, for example, to communicate with input or output devices such as a display screen, a touch sensitive surface, a printer, or any other suitable device. Other componentry and functionality not reflected in the illustrations will be apparent in light of this disclosure, and it will be appreciated that other embodiments are not limited to any particular hardware or software configuration. Thus, in other embodiments, system  400  may include additional, fewer, or alternative subcomponents as compared to those included in the embodiment of  FIG. 4 . 
     The non-transitory computer readable medium may be any suitable medium for storing digital information, such as a hard drive, a server, a flash memory, or random access memory (RAM), or a combination of memories. In alternative embodiments, the components or modules disclosed herein may be implemented with hardware, including gate level logic such as a field-programmable gate array (FPGA), or alternatively, a purpose-built semiconductor such as an application-specific integrated circuit (ASIC). Still other embodiments may be implemented with a microcontroller having one or more input/output ports for receiving and outputting data, and one or more embedded routines for carrying out the various functionalities disclosed herein. It will be apparent that any suitable combination of hardware, software, and firmware may be used, and that other embodiments are not limited to any particular system architecture. 
     Some embodiments may be implemented, for example, using a machine readable medium or article which may store an instruction or a set of instructions that, if executed by a machine, may cause the machine to perform a method or operations in accordance with the embodiments. Such a machine may include, for example, any suitable processing platform, computing platform, computing device, processing device, computing system, processing system, computer, process, or the like, and may be implemented using any suitable combination of hardware and software. The machine readable medium or article may include, for example, any suitable type of memory unit, memory device, memory article, memory medium, storage device, storage article, storage medium, or storage unit, such as memory, removable or non-removable media, erasable or non-erasable media, writeable or rewriteable media, digital or analog media, hard disk, floppy disk, compact disk read only memory (CD-ROM), compact disk recordable (CD-R) memory, compact disk rewriteable (CR-RW) memory, optical disk, magnetic media, magneto-optical media, removable memory cards or disks, various types of digital versatile disk (DVD), a tape, a cassette, or the like. The instructions may include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, encrypted code, and the like, implemented using any suitable high level, low level, object oriented, visual, compiled, or interpreted programming language. 
     Unless specifically stated otherwise, it may be appreciated that terms such as “processing,” “computing,” “calculating,” “determining,” or the like refer to the action or process of a computer or computing system, or similar electronic computing device, that manipulates or transforms data represented as physical quantities (for example, electronic) within the registers or memory units of the computer system into other data similarly represented as physical quantities within the registers, memory units, or other such information storage transmission or displays of the computer system. The embodiments are not limited in this context. 
     The terms “circuit” or “circuitry,” as used in any embodiment herein, are functional and may include, for example, singly or in any combination, hardwired circuitry, programmable circuitry such as computer processors including one or more individual instruction processing cores, state machine circuitry, or firmware that stores instructions executed by programmable circuitry. The circuitry may include a processor or controller configured to execute one or more instructions to perform one or more operations described herein. The instructions may be embodied as, for example, an application, software, firmware, etc., configured to cause the circuitry to perform any of the operations. Software may be embodied as a software package, code, instructions, instruction sets, or data recorded on a computer-readable storage device. Software may be embodied or implemented to include any number of processes, and processes, in turn, may be embodied or implemented to include any number of threads, etc., in a hierarchical fashion. Firmware may be embodied as code, instructions or instruction sets, or data that are hard-coded (e.g., nonvolatile) in memory devices. 
     The circuitry may, collectively or individually, be embodied as circuitry that forms part of a larger system, for example, an integrated circuit (IC), an application-specific integrated circuit (ASIC), a system on-chip (SoC), desktop computers, laptop computers, tablet computers, servers, smart phones, etc. Other embodiments may be implemented as software executed by a programmable control device. In such cases, the terms “circuit” or “circuitry” are intended to include a combination of software and hardware such as a programmable control device or a processor capable of executing the software. As described herein, various embodiments may be implemented using hardware elements, software elements, or any combination thereof. Examples of hardware elements may include processors, microprocessors, circuits, circuit elements (e.g., transistors, resistors, capacitors, inductors, and so forth), integrated circuits, application specific integrated circuits (ASIC), programmable logic devices (PLD), digital signal processors (DSP), field programmable gate array (FPGA), logic gates, registers, semiconductor device, chips, microchips, chip sets, and so forth. 
     Numerous specific details have been set forth herein to provide a thorough understanding of the embodiments. It will be understood in light of the present disclosure, however, that the embodiments may be practiced without these specific details. In other instances, well known operations, components, and circuits have not been described in detail so as not to obscure the embodiments. It may be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments. In addition, although the subject matter has been described in language specific to structural features or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described herein. Rather, the specific features and acts described herein are disclosed as example forms of implementing the claims. 
     Further Example Embodiments 
     The following examples pertain to further embodiments, from which numerous permutations and configurations will be apparent. 
     Example 1 is a processor-implemented method for three-dimensional (3D) reconstruction of a dynamic scene as a set of voxels. The method includes: receiving, by the processor, image data from each of two or more spatially-separated sensors observing the scene from a corresponding two or more vantage points; fusing, by the processor, the image data into the set of voxels on a frame-by-frame basis; segmenting, by the processor, the image data into objects that constitute the scene; detecting, by the processor, which of the objects remain static from frame to frame, remaining ones of the objects being dynamic; and outputting, by the processor to a display device, those of the voxels corresponding to the dynamic objects and not to the static objects. 
     Example 2 includes the subject matter of Example 1, further including selecting, by the processor, only those of the voxels currently visible to a user of the display device, to produce a sparse subset of the voxels. The outputting of the voxels further includes only outputting those of the voxels belonging to the sparse subset. 
     Example 3 includes the subject matter of Example 2, further including filtering, by the processor, the sparse subset to remove those of the voxels corresponding to the static objects, to produce a dynamic subset of the sparse subset. The outputting of the voxels further includes only outputting those of the voxels belonging to the dynamic sparse subset. 
     Example 4 includes the subject matter of Example 3, further including mapping, by the processor, the static objects to their corresponding ones of the voxels. 
     Example 5 includes the subject matter of any of Examples 2 through 4, further including organizing the sparse subset in a sparse voxel octree (SVO) format. 
     Example 6 includes the subject matter of any of the preceding Examples, further including filtering, by the processor, the set of voxels to remove those of the voxels corresponding to the static objects, to produce a dynamic subset of the voxels. The outputting of the voxels further includes only outputting those of the voxels belonging to the dynamic sub set. 
     Example 7 includes the subject matter of Example 6, further including mapping, by the processor, the static objects to their corresponding ones of the voxels. 
     Example 8 includes the subject matter of Examples 1 through 7, further including: receiving, by the display device, the voxels corresponding to the dynamic objects; rendering, by the display device, the received voxels corresponding to the dynamic objects; and rendering, by the display device, voxels corresponding to the static objects received during earlier frames. 
     Example 9 is a system for three-dimensional (3D) reconstruction of a dynamic scene as a set of voxels. The system includes: a data capture circuit to receive image data from each of two or more spatially-separated sensors observing the scene from a corresponding two or more vantage points; an image processing circuit to fuse the image data into the set of voxels on a frame-by-frame basis; an object segmentation circuit to segment the image data into objects that constitute the scene; a motion detection circuit to detect which of the objects remain static from frame to frame, remaining ones of the objects being dynamic; and a voxel output circuit to output, to a display device, those of the voxels corresponding to the dynamic objects and not to the static objects. 
     Example 10 includes the subject matter of Example 9, further including a voxel selection circuit to select only those of the voxels currently visible to a user of the display device, to produce a sparse subset of the voxels. The voxel output circuit is further to only output those of the voxels belonging to the sparse subset. 
     Example 11 includes the subject matter of Example 10, further including a static filter circuit to filter the sparse subset to remove those of the voxels corresponding to the static objects, to produce a dynamic subset of the sparse subset. The voxel output circuit is further to only output those of the voxels belonging to the dynamic sparse subset. 
     Example 12 includes the subject matter of Example 11, further including a voxel mapping circuit to map the static objects to their corresponding ones of the voxels. 
     Example 13 includes the subject matter of any of Examples 10 through 12, the voxel selection circuit being further to organize the sparse subset in a sparse voxel octree (SVO) format. 
     Example 14 includes the subject matter of any of Examples 9 through 13, further including a static filter circuit to filter the set of voxels to remove those of the voxels corresponding to the static objects, to produce a dynamic subset of the voxels. The voxel output circuit is further to only output those of the voxels belonging to the dynamic subset. 
     Example 15 includes the subject matter of Example 14, further including a voxel mapping circuit to map the static objects to their corresponding ones of the voxels. 
     Example 16 includes the subject matter of any of Examples 9 through 15, the display device being to receive the voxels corresponding to the dynamic objects, render the received voxels corresponding to the dynamic objects, and render voxels corresponding to the static objects received during earlier frames. 
     Example 17 is at least one non-transitory computer readable storage medium having instructions encoded thereon that, when executed by one or more processors, result in the following operations for three-dimensional (3D) reconstruction of a dynamic scene as a set of voxels being performed. The operations include: receiving image data from each of two or more spatially-separated sensors observing the scene from a corresponding two or more vantage points; fusing the image data into the set of voxels on a frame-by-frame basis; segmenting the image data into objects that constitute the scene; detecting which of the objects remain static from frame to frame, remaining ones of the objects being dynamic; and outputting to a display device those of the voxels corresponding to the dynamic objects and not to the static objects. 
     Example 18 includes the subject matter of Example 17, the operations further including selecting only those of the voxels currently visible to a user of the display device, to produce a sparse subset of the voxels. The outputting of the voxels further includes only outputting those of the voxels belonging to the sparse subset. 
     Example 19 includes the subject matter of Example 18, the operations further including filtering the sparse subset to remove those of the voxels corresponding to the static objects, to produce a dynamic subset of the sparse subset. The outputting of the voxels further includes only outputting those of the voxels belonging to the dynamic sparse subset. 
     Example 20 includes the subject matter of Example 19, the operations further including mapping the static objects to their corresponding ones of the voxels. 
     Example 21 includes the subject matter of any of Examples 18 through 20, the operations further including organizing the sparse subset in a sparse voxel octree (SVO) format. 
     Example 22 includes the subject matter of any of Examples 17 through 21, the operations further including filtering the set of voxels to remove those of the voxels corresponding to the static objects, to produce a dynamic subset of the voxels. The outputting of the voxels further includes only outputting those of the voxels belonging to the dynamic sub set. 
     Example 23 includes the subject matter of Example 22, the operations further including mapping the static objects to their corresponding ones of the voxels. 
     Example 24 includes the subject matter of any of Example 17 through 23, the display device being to receive the voxels corresponding to the dynamic objects, render the received voxels corresponding to the dynamic objects, and render voxels corresponding to the static objects received during earlier frames. 
     Example 25 is a system for three-dimensional (3D) reconstruction of a dynamic scene as a set of voxels. The system includes: means for receiving image data from each of two or more spatially-separated sensors observing the scene from a corresponding two or more vantage points; means for fusing the image data into the set of voxels on a frame-by-frame basis; means for segmenting the image data into objects that constitute the scene; means for detecting which of the objects remain static from frame to frame, remaining ones of the objects being dynamic; and means for outputting to a display device those of the voxels corresponding to the dynamic objects and not to the static objects. 
     Example 26 includes the subject matter of Example 25, further including means for selecting only those of the voxels currently visible to a user of the display device, to produce a sparse subset of the voxels. The means for outputting of the voxels further includes means for only outputting those of the voxels belonging to the sparse subset. 
     Example 27 includes the subject matter of Example 26, further including means for filtering the sparse subset to remove those of the voxels corresponding to the static objects, to produce a dynamic subset of the sparse subset. The means for outputting of the voxels further includes means for only outputting those of the voxels belonging to the dynamic sparse sub set. 
     Example 28 includes the subject matter of Example 27, further including means for mapping the static objects to their corresponding ones of the voxels. 
     Example 29 includes the subject matter of any of Examples 26 through 28, further including means for organizing the sparse subset in a sparse voxel octree (SVO) format. 
     Example 30 includes the subject matter of any of Examples 25 through 29, further including means for filtering the set of voxels to remove those of the voxels corresponding to the static objects, to produce a dynamic subset of the voxels. The means for outputting of the voxels further includes means for only outputting those of the voxels belonging to the dynamic subset. 
     Example 31 includes the subject matter of Example 30, further including means for mapping the static objects to their corresponding ones of the voxels. 
     Example 32 includes the subject matter of any of Examples 25 through 31, the display device being to receive the voxels corresponding to the dynamic objects, render the received voxels corresponding to the dynamic objects, and render voxels corresponding to the static objects received during earlier frames. 
     The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible within the scope of the claims. Accordingly, the claims are intended to cover all such equivalents. Various features, aspects, and embodiments have been described herein. The features, aspects, and embodiments are susceptible to combination with one another as well as to variation and modification, as will be understood in light of the present disclosure. The present disclosure should therefore be considered to encompass such combinations, variations, and modifications. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto. Future filed applications claiming priority to this application may claim the disclosed subject matter in a different manner, and may generally include any set of one or more elements as variously disclosed or otherwise demonstrated herein.