Method, apparatus and computer program for instance-based mesh coding - Patents.com

Abstract

A method and apparatus comprising computer code configured to cause one or more processors to obtain an input mesh corresponding to volumetric data of at least one three-dimensional (3D) visual content, partition the input mesh into a plurality of sub-meshes, each of the sub-meshes including a respective one of the instances of an object, determine a similarity between at least two of the instances of the object, group the sub-meshes based on the determined similarity, and code the volumetric data based on the grouping of the sub-meshes.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 392,409, filed July 26, 2022, and U.S. Patent Application No. 18 / 312,338, filed May 4, 2023, the disclosures of which are incorporated by reference in their entireties herein.

[0002] This disclosure is directed to a set of advanced video coding techniques, including both lossless and lossy mesh coding techniques that are based on mesh instances. [Background technology]

[0003] Advances in 3D capture, modeling, and rendering are facilitating the ubiquity of 3D content across several platforms and devices. Today, it may be possible to capture a baby's first steps on one continent while grandparents on another continent watch (and maybe even interact with) that child, enjoying a fully immersive experience together. Nevertheless, to achieve such realism, models are becoming ever more sophisticated, and significant amounts of data are tied to the creation and consumption of those models.

[0004] VMesh is an ongoing MPEG standard for compressing static and dynamic meshes. VMesh separates the input mesh into a simplified base mesh and a residual mesh. The base mesh can be encoded at high quality, while the residual mesh can be encoded using subdivision surface fitting and displacement encoding to exploit local properties.

[0005] However, complex meshes often contain information about multiple instances to associate texture maps. This information is available at the time of encoding. On the other hand, meshes can be segmented into several parts based on their characteristics. For example, there are more polygons in the face region of a human mesh.

[0006] Thus, a constant quantization step size applied to all instances, objects, parts in a mesh will result in large quantization errors, mesh regions may not be equally important, the number of faces may vary significantly in different parts of the mesh, the base mesh may be simpler than the original mesh and displacements and therefore may not require as much bit depth precision. Therefore, for any of those reasons, a technical solution to such problems that have arisen in video coding technology is desired. Summary of the Invention [Means for solving the problem]

[0007] Methods and apparatuses are included that include a memory configured to store computer program code and one or more processors configured to access the computer program code and operate as instructed by the computer program code, the computer program being configured to cause the processor to implement: an acquiring code configured to cause the at least one processor to acquire an input mesh corresponding to volumetric data of at least one three-dimensional (3D) visual content; a partitioning code configured to cause the at least one processor to partition the input mesh corresponding to the volumetric data into a plurality of sub-meshes, each of the sub-meshes including a respective one of the instances of the object; a determining code configured to cause the at least one processor to determine a similarity between at least two of the instances of the object; a grouping code configured to cause the at least one processor to group the sub-meshes based on the determined similarity; and a coding code configured to cause the at least one processor to code the volumetric data based on the grouping of the plurality of sub-meshes.

[0008] According to an example embodiment, determining the similarity may include comparing bounding boxes of at least two of the sub-meshes.

[0009] According to an example embodiment, comparing the bounding boxes may include comparing ratios of dimensions of the bounding boxes.

[0010] According to an example embodiment, coding the volumetric data may include signaling a different one of the codecs for each one of at least two of the sub-meshes.

[0011] According to an example embodiment, coding the volumetric data may include signaling a prediction of a first one of the at least two of the submeshes based on a prediction of a second one of the at least two of the submeshes.

[0012] According to an example embodiment, coding the volumetric data may include signaling only a single prediction index for an entire first of the at least two of the sub-meshes.

[0013] According to an example embodiment, coding the volumetric data may include signaling only a plurality of prediction indexes for a first of the at least two of the sub-meshes.

[0014] According to an example embodiment, a first one of the plurality of prediction indexes may be based on a first prediction index, a second one of the plurality of prediction indexes may be based on a second prediction index, the first prediction index may be based on a first other prediction index that is a prediction index for a second one of the at least two submeshes, and the second one of the plurality of prediction indexes may be based on a second other prediction index that is a prediction index for a third one of the at least two submeshes.

[0015] According to an example embodiment, signaling a prediction for a first of the at least two of the submeshes may include signaling a first prediction index and a second prediction index, where the first prediction index may be a single index collectively set to each of a plurality of vertices of the first of the at least two of the submeshes and the second prediction index may be set to at least one other vertex of the first of the at least two of the submeshes.

[0016] According to an example embodiment, at least one of the first prediction index and the second prediction index may be based on a prediction index set for at least one vertex of a second of the at least two of the submeshes.

[0017] Further features, nature and various advantages of the disclosed subject matter will become more apparent from the following detailed description and the accompanying drawings. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a schematic diagram according to an embodiment. [Diagram 2] FIG. 2 is a simplified block diagram according to an embodiment. [Diagram 3] FIG. 2 is a simplified diagram according to an embodiment. [Figure 4] FIG. 2 is a simplified diagram according to an embodiment. [Diagram 5] FIG. 2 is a simplified diagram according to an embodiment. [Figure 6] FIG. 2 is a simplified diagram according to an embodiment. [Figure 7] FIG. 2 is a simplified diagram according to an embodiment. [Figure 8] FIG. 2 is a simplified diagram according to an embodiment. [Figure 9] FIG. 2 is a simplified diagram according to an embodiment. [Figure 10] FIG. 2 is a simplified diagram according to an embodiment. [Figure 11] FIG. 2 is a simplified diagram according to an embodiment. [Figure 12] FIG. 2 is a simplified diagram according to an embodiment. [Figure 13] FIG. 2 is a simplified flow diagram according to an embodiment. [Figure 14] FIG. 2 is a simplified flow diagram according to an embodiment. [Figure 15] FIG. 2 is a simplified flow diagram according to an embodiment. [Figure 16] FIG. 2 is a simplified diagram according to an embodiment. [Figure 17]FIG. 2 is a simplified diagram according to an embodiment. [Figure 18] FIG. 2 is a simplified diagram according to an embodiment. [Figure 19] FIG. 2 is a simplified diagram according to an embodiment. [Figure 20] FIG. 2 is a simplified flow diagram according to an embodiment. [Figure 21] FIG. 2 is a simplified diagram according to an embodiment. [Figure 22] FIG. 2 is a simplified flow diagram according to an embodiment. [Diagram 23] FIG. 2 is a simplified flow diagram according to an embodiment. [Figure 24] 1 is a simplified diagram according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The proposed features described below may be used individually or combined in any order. Furthermore, the embodiments may be implemented by processing circuitry (e.g., one or more processors or one or more integrated circuits). In one example, the one or more processors execute a program stored on a non-transitory computer-readable medium.

[0020] 1 shows a simplified block diagram of a communication system 100 according to one embodiment of the present disclosure. The communication system 100 may include at least two terminals 102, 103 interconnected via a network 105. For unidirectional transmission of data, a first terminal 103 may code video data at a local location for transmission to the other terminal 102 via the network 105. The second terminal 102 may receive the coded video data of the other terminal from the network 105, decode the coded data, and display the recovered video data. Unidirectional data transmission may be common in media provision applications, etc.

[0021] 1 illustrates a second pair of terminals 101 and 104 provided to support bidirectional transmission of coded video, such as may occur during a video conference. For the bidirectional transmission of data, each terminal 101 and 104 may code video data captured at a local location for transmission to the other terminal over network 105. Each terminal 101 and 104 may also receive coded video data transmitted by the other terminal, may decode the coded data, and may display the recovered video data on a local display device.

[0022] In FIG. 1, terminals 101, 102, 103, and 104 may be illustrated as servers, personal computers, and smartphones, although the principles of the present disclosure are not so limited. Embodiments of the present disclosure find application with laptop computers, tablet computers, media players, and / or dedicated video conferencing equipment. Network 105 represents any number of networks that convey coded video data between terminals 101, 102, 103, and 104, including, for example, wired and / or wireless communication networks. Communication network 105 may exchange data in circuit-switched and / or packet-switched channels. Representative networks include telecommunications networks, local area networks, wide area networks, and / or the Internet. For purposes of this discussion, the architecture and topology of network 105 may not be important to the operation of the present disclosure unless described below herein.

[0023] 2 illustrates the arrangement of a video encoder and a video decoder in a streaming environment as one example of an application of the disclosed subject matter. The subject matter of this disclosure may be equally applicable to other video-enabled applications, such as, for example, video conferencing, digital television, storage of compressed video on digital media including CDs, DVDs, memory sticks, and the like.

[0024] The streaming system may include a capture subsystem 203, which may include a video source 201, such as a digital camera, that creates an uncompressed video sample stream 213. The sample stream 213 may be emphasized as a high data volume when compared to an encoded video bitstream and may be processed by an encoder 202 coupled to the video source 201, which may be a camera, as described above. The encoder 202 may include hardware, software, or a combination thereof to enable or implement aspects of the disclosed subject matter, as described in more detail below. The encoded video bitstream 204 may be emphasized as a lower data volume compared to the sample stream and may be stored on a streaming server 205 for future use. One or more streaming clients 212 and 207 may access the streaming server 205 to retrieve copies 208 and 206 of the encoded video bitstream 204. The client 212 may include a video decoder 211 to decode the incoming copy 208 of the encoded video bitstream and create an outgoing video sample stream 210 that may be rendered on a display 209 or other rendering device (not shown). In some streaming systems, the video bitstreams 204, 206, and 208 may be encoded according to a particular video coding / compression standard, examples of which are mentioned above and further described herein.

[0025] FIG. 3 may be a functional block diagram of a video decoder 300 according to one embodiment of the present invention.

[0026] The receiver 302 may receive one or more codec video sequences to be decoded by the decoder 300, in the same or another embodiment, one coded video sequence at a time, with the decoding of each coded video sequence being independent of the other coded video sequences. The coded video sequences may be received from a channel 301, which may be a hardware / software link to a storage device that stores the encoded video data. The receiver 302 may receive the encoded video data along with other data, such as coded audio data and / or auxiliary data streams, that may be forwarded to a respective usage entity (not shown). The receiver 302 may separate the coded video sequences from the other data. To combat network jitter, a buffer memory 303 may be coupled between the receiver 302 and the entropy decoder / parser 304 (hereinafter "parser"). If the receiver 302 is receiving data from a storage / forwarding device with sufficient bandwidth and controllability, or from an isosynchronous network, the buffer 303 may not be necessary or may be small. For use in a best effort packet network such as the Internet, buffer 303 may be required and may be relatively large, and may advantageously be of adaptive size.

[0027] The video decoder 300 may include a parser 304 for reconstructing symbols 313 from the entropy coded video sequence. The categories of symbols include information used to manage the operation of the decoder 300 and potentially information for controlling a rendering device, such as a display 312, that is not an integral part of the decoder but may be coupled to it. The control information for the rendering device may be in the form of a supplemental enhancement information (SEI message) or a video usability information (VUI) parameter set fragment (not shown). The parser 304 may parse / entropy decode the received coded video sequence. The coding of the coded video sequence may follow a video coding technique or standard and may follow principles well known to those skilled in the art, including variable length coding, Huffman coding, arithmetic coding with or without context dependency, etc. The parser 304 may extract from the coded video sequence a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder based on at least one parameter corresponding to that group. The subgroups may include Group of Pictures (GOP), pictures, tiles, slices, macroblocks, coding units (CUs), blocks, transform units (TUs), prediction units (PUs), etc. The entropy decoder / parser may also extract from the coded video sequence information such as transform coefficients, quantizer parameter values, motion vectors, etc.

[0028] The parser 304 may perform an entropy decoding / parsing operation on the video sequence received from the buffer 303 to create symbols 313. The parser 304 may receive the encoded data and selectively decode particular symbols 313. Additionally, the parser 304 may determine whether a particular symbol 313 should be provided to the motion compensated prediction unit 306, the scaler / inverse transform unit 305, the intra prediction unit 307, or the loop filter 311.

[0029] The reconstruction of symbols 313 may involve several different units depending on the type of coded video picture or part thereof (inter-picture and intra-picture, inter-block and intra-block, etc.), as well as other factors. Which units are involved and how can be controlled by subgroup control information parsed from the coded video sequence by parser 304. The flow of such subgroup control information between parser 304 and the following units is not shown for clarity.

[0030] Besides the already mentioned functional blocks, the decoder 300 can be conceptually subdivided into several functional units, as described below. In an actual implementation operating under commercial constraints, many of these units will closely interact with each other and may be at least partially integrated with each other. However, for the purposes of describing the disclosed subject matter, the following conceptual subdivision into functional units is appropriate:

[0031] The first unit is a scalar / inverse transform unit 305. The scalar / inverse transform unit 305 receives quantized transform coefficients and control information including the transform to use, block size, quantization factor, quantization scaling matrix, etc. as symbols 313 from the parser 304. It can output blocks containing sample values ​​that can be input to the aggregator 310.

[0032] In some cases, the output samples of the scalar / inverse transform unit 305 may relate to intra-coded blocks, i.e., blocks that do not use prediction information from a previously reconstructed picture, but can use prediction information from a previously reconstructed part of the current picture. Such prediction information can be provided by the intra-picture prediction unit 307. In some cases, the intra-picture prediction unit 307 uses surrounding already reconstructed information fetched from the current (partially reconstructed) picture 309 to generate a block of the same size and shape as the block being reconstructed. The aggregator 310 adds, possibly on a sample-by-sample basis, the prediction information generated by the intra-prediction unit 307 to the output sample information provided by the scalar / inverse transform unit 305.

[0033] In other cases, the output samples of the scalar / inverse transform unit 305 may relate to an inter-coded, potentially motion-compensated block. In such cases, the motion compensated prediction unit 306 may access the reference picture memory 308 to fetch samples used for prediction. After motion compensating the fetched samples according to the symbols 313 relating to the block, these samples may be added by the aggregator 310 to the output of the scalar / inverse transform unit to generate output sample information (in this case referred to as residual samples or residual signals). The addresses in the reference picture memory format from which the motion compensation unit fetches the prediction samples may be controlled by a motion vector and may be made available to the motion compensation unit in the form of symbols 313 that may have, for example, X, Y, and reference picture components. Motion compensation may also include interpolation of sample values ​​fetched from the reference picture memory when sub-sample accurate motion vectors are used, motion vector prediction mechanisms, etc.

[0034] The output samples of the aggregator 310 may be subjected to various loop filtering techniques in a loop filter unit 311. The video compression techniques may include in-loop filter techniques controlled by parameters contained in the coded video bitstream and available to the loop filter unit 311 as symbols 313 from the parser 304, but may also be responsive to meta-information obtained during decoding of a coded picture or a previous (in decoding order) part of a coded video sequence, or to previously reconstructed and loop filtered sample values.

[0035] The output of the loop filter unit 311 can be a sample stream that can be output to the rendering device 312 as well as stored in the reference picture memory 557 for use in future inter-picture prediction.

[0036] Once fully reconstructed, a particular coded picture can be used as a reference picture for future prediction. Once a coded picture is fully reconstructed and the coded picture has been identified as a reference picture (e.g., by parser 304), the current reference picture 309 can become part of the reference picture buffer 308, and a new current picture memory can be reallocated before starting reconstruction of the following coded picture.

[0037] The video decoder 300 may perform decoding operations according to a given video compression technique, which may be documented in a standard specification, such as ITU-T Rec. H.265. The coded video sequence may conform to the syntax specified by the video compression technique or standard being used, in the sense that it complies with the syntax of the video compression technique or standard, as specified in the video compression technical document or standard, and specifically as specified in the profile documented therein. Also, what is required for compliance may be that the complexity of the coded video sequence is within a range defined by the level of the video compression technique or standard. In some cases, the level limits the maximum picture size, the maximum frame rate, the maximum reconstructed sample rate (e.g., measured in megasamples per second), the maximum reference picture size, etc. The limits set by the level may be further limited in some cases by the specification of a hypothetical reference decoder (HRD) and metadata for HRD buffer management signaled within the coded video sequence.

[0038] In one embodiment, the receiver 302 may receive additional (redundant) data along with the encoded video. The additional data may be included as part of the coded video sequence. The additional data may be used by the video decoder 300 to properly decode the data and / or to more accurately reconstruct the original video data. The additional data may be in the form of, for example, a temporal layer, a spatial layer, or a signal-to-noise ratio (SNR) enhancement layer, redundant slices, redundant pictures, forward error correction codes, etc.

[0039] FIG. 4 may be a functional block diagram of a video encoder 400 according to one embodiment of the present disclosure.

[0040] The encoder 400 may receive video samples from a video source 401 (not part of the encoder), which may capture video images to be coded by the encoder 400 .

[0041] The video source 401 may provide a source video sequence to be coded by the encoder (303) in the form of a digital video sample stream that can be of any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit, ...), any color space (e.g., BT.601 Y CrCB, RGB, ...) and any suitable sampling structure (e.g., Y CrCb 4:2:0, Y CrCb 4:4:4). In a media serving system, the video source 401 may be a storage device that stores previously prepared video. In a video conferencing system, the video source 401 may be a camera that captures local image information as a video sequence. The video data may be provided as a number of separate pictures that give motion when viewed in sequence. The pictures themselves may be organized as a spatial array of pixels, each of which may contain one or more samples, depending on the sampling structure, color space, etc., in use. Those skilled in the art can easily understand the relationship between pixels and samples. The following description focuses on samples.

[0042] According to an embodiment, the encoder 400 may code and compress pictures of a source video sequence into a coded video sequence 410 in real-time or under any other time constraint as required by an application. Providing an appropriate coding rate is one function of the controller 402. The controller controls and is functionally coupled to other functional units as described below. For clarity, couplings are not depicted. Parameters set by the controller may include rate control related parameters (picture skip, quantizer, lambda value of rate distortion optimization technique, etc.), picture size, Group of Pictures (GOP) layout, maximum motion vector search range, etc. Those skilled in the art may easily identify other functions of the controller 402 as they may relate to the video encoder 400 being optimized for a particular system design.

[0043] Some video encoders operate in what those skilled in the art will easily recognize as a "coding loop." As an oversimplified explanation, the coding loop can consist of an encoding part of the encoder 400 (hereafter "source coder") (responsible for creating symbols based on the input picture to be coded and reference pictures), and a (local) decoder 406 embedded in the encoder 400 that reconstructs the symbols to create sample data that the (remote) decoder will also create (since any compression between the symbols and the coded video bitstream is lossless in the video compression techniques considered in the disclosed subject matter). The reconstructed sample stream is input to a reference picture memory 405. Since decoding of the symbol stream results in bit-exact results regardless of the location of the decoder (local or remote), the reference picture buffer contents are also bit-exact between the local and remote encoders. In other words, the predictive part of the encoder "sees" exactly the same sample values ​​as the decoder "sees" when using prediction during decoding as reference picture samples. This basic principle of reference picture synchrony (and the resulting drift when synchrony cannot be maintained, for example due to channel errors) is well known to those skilled in the art.

[0044] The operation of the "local" decoder 406 may be the same as that of the "remote" decoder 300, which has already been described in detail above in relation to Figure 3. However, with brief reference also to Figure 4, because symbols are available and the encoding / decoding of symbols into a coded video sequence by the entropy coder 408 and the parser 304 may be lossless, the entropy decoding portion of the decoder 300, including the channel 301, the receiver 302, the buffer 303, and the parser 304, may not be fully implemented in the local decoder 406.

[0045] At this point, it can be said that any decoder technology, other than parsing / entropy decoding, present in the decoder must necessarily also be present in the corresponding encoder in substantially the same functional form. A description of the encoder technology can be omitted, since it is the inverse of the decoder technology, which has been described generically. Only in certain areas is a more detailed description necessary, which is provided below.

[0046] As part of its operation, the source coder 403 may perform motion compensated predictive coding, which predictively codes an input frame with reference to one or more previously coded frames from the video sequence, designated as “reference frames.” In this method, the coding engine 407 codes differences between pixel blocks of the input frame and pixel blocks of reference frames that may be selected as predictive references for the input frame.

[0047] The local video decoder 406 may decode the coded video data of the frames that may be designated as reference frames based on the symbols created by the source coder 403. The operation of the coding engine 407 may preferably be a lossy process. When the coded video data may be decoded in a video decoder (not shown in FIG. 4), the reconstructed video sequence may be a copy of the source video sequence, usually with some errors. The local video decoder 406 may replicate the decoding process that may be performed on the reference frames by the video decoder, and store the reconstructed reference frames in the reference picture memory 405, which may be, for example, a cache. In this way, the encoder 400 may locally store copies of the reconstructed reference frames that have common content as the reconstructed reference frames that will be obtained by the far-end video decoder (without transmission errors).

[0048] The predictor 404 may perform a predictive search for the coding engine 407. That is, for a new frame to be coded, the predictor 404 may search the reference picture memory 405 for sample data (as candidate reference pixel blocks) or specific metadata, such as reference picture motion vectors, block shapes, etc., that may serve as suitable predictive references for the new picture. The predictor 404 may operate on a pixel block by pixel block basis to find suitable predictive references. In some cases, as determined by the search results obtained by the predictor 404, the input picture may have predictive references drawn from multiple reference pictures stored in the reference picture memory 405.

[0049] The controller 402 may manage the coding operations of a source coder 403, which may be, for example, a video coder, including, for example, setting parameters and subgroup parameters used to encode the video data.

[0050] The output of all the aforementioned functional units may undergo entropy coding in an entropy coder 408. The entropy coder converts the symbols produced by the various functional units into a coded video sequence by losslessly compressing the symbols according to techniques known to those skilled in the art, such as, for example, Huffman coding, variable length coding, arithmetic coding, etc.

[0051] The transmitter 409 may buffer the coded video sequence created by the entropy coder 408 and prepare it for transmission over a communication channel 411, which may be a hardware / software link to a storage device that will store the encoded video data. The transmitter 409 may merge the coded video data from the source coder 403 with other data to be transmitted, such as coded audio data and / or an auxiliary data stream (source not shown).

[0052] The controller 402 may manage the operation of the encoder 400. During coding, the controller 402 may assign a particular coded picture type to each coded picture, which may affect the coding technique that may be applied to each picture. For example, pictures may often be assigned as one of the following frame types:

[0053] An intra picture (I-picture) may be one that can be coded and decoded without using other frames in a sequence as a source of prediction. Some video codecs allow various types of intra pictures, including, for example, independent decoder refresh pictures. Those skilled in the art are aware of these variations of I-pictures, as well as their respective applications and characteristics.

[0054] A predictive picture (P picture) may be one that can be coded and decoded using intra- or inter-prediction, which uses at most one motion vector and reference index to predict the sample values ​​of each block.

[0055] Bidirectionally predicted pictures (B-pictures) may be those that can be coded and decoded using intra- or inter-prediction, which uses up to two motion vectors and reference indices to predict the sample values ​​of each block. Similarly, multi-predictive pictures can use more than two reference pictures and associated metadata to reconstruct a single block.

[0056] A source picture may generally be spatially subdivided into multiple sample blocks (e.g., blocks of 4x4, 8x8, 4x8, or 16x16 samples, respectively) and coded block by block. A block may be predictively coded with reference to other (already coded) blocks as determined by the coding assignment applied to the block's respective picture. For example, a block of an I-picture may be non-predictively coded or predictively coded with reference to already coded blocks of the same picture (spatial or intra prediction). A pixel block of a P-picture may be non-predictively coded via spatial prediction or via temporal prediction with reference to one previously coded reference picture. A block of a B-picture may be non-predictively, via spatial prediction, or via temporal prediction with reference to one or two previously coded reference pictures.

[0057] Encoder 400, which may be, for example, a video coder, may perform coding operations according to a given video coding technique or standard, such as ITU-T Rec. H.265. In its operations, encoder 400 may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancy in an input video sequence. Thus, the coded video data may conform to a syntax specified by the video coding technique or standard being used.

[0058] In one embodiment, the transmitter 409 may transmit additional data along with the encoded video. The source coder 403 may include such data as part of the coded video sequence. The additional data may include temporal / spatial / SNR enhancement layers, other forms of redundant data such as redundant pictures and slices, Supplemental Enhancement Information (SEI) messages, Visual Usability Information (VUI) parameter set fragments, etc.

[0059] FIG. 5 shows a simplified block-style workflow diagram 500 of example viewport-dependent processing in Omnidirectional Media Application Format (OMAF) that may enable 360-degree virtual reality (VR360) streaming described in OMAF.

[0060] In acquisition block 1001, video data A, such as multiple image and audio data of the same time instance, is acquired if the image data may represent a VR360 scene. In processing block 1003, image B of the same time instance is acquired. i are processed by one or more of stitching, mapping to a projected picture for one or more virtual reality (VR) angles or other angles / viewpoints, and packed by region. In addition, metadata indicating any of such processed and other information may be created to aid in the distribution and rendering process.

[0061] For data D, in the image encoding block 1005, the projected picture is i In viewport independent streaming, the video pictures are encoded into a data stream in a video encoding block 1004, for example as a single-layer bitstream. v and data B is encoded as a Regarding the audio data, the audio data is also encoded in the audio encoding block 1002 as data E a can be encoded into

[0062] Data E a , E v , and E i , the coded bitstream F iand / or the entire F may be stored in a (content delivery network (CDN) / cloud) server, typically at a distribution block 1007 or otherwise transmitted in its entirety to an OMAF player 1020, and decoded in its entirety by a decoder, whereby at least the area of ​​the decoded picture corresponding to the current viewport is rendered to the user at a display block 1016, along with various metadata, file playback, and orientation / viewport metadata from a head / eye tracking block 1008, e.g., regarding the angle the user may be looking through the VR imaging device with respect to the viewport specifications of that device. A distinct feature of VR360 is that only a viewport may be displayed at any particular time, and such a feature may be exploited to improve the performance of an omnidirectional video system by selective delivery according to the user's viewport (or any other criteria, such as recommended viewport timed metadata). For example, viewport-dependent delivery may be enabled by tile-based video coding according to an exemplary embodiment.

[0063] Similar to the encoding blocks discussed above, the OMAF player 1020 according to an exemplary embodiment may generate data F′ and / or F′ i and similarly reverse one or more facets of such encoding with respect to file / segment deencapsulation of one or more of the metadata to generate audio data E' at audio decoding block 1010. i , the video decoding block 1013 receives the video data E' v , and image data E' in image decoding block 1014. i is decoded to data B' in the audio rendering block 1011. a and image rendering of data D' in image rendering block 1015 to render display data A' in display block 1016 in VR360 format according to various metadata such as orientation / viewport metadata. iand audio data A' at speaker / headphone block 1012 s It should be understood that various metadata may affect one of the data decoding and rendering processes depending on various tracks, languages, qualities, views that may be selected by or for a user of the OMAF player 1020, and that the order of processing described herein is presented for an exemplary embodiment and may be performed in other orders according to other exemplary embodiments.

[0064] 6 illustrates a simplified block-style content flow process diagram 600 of (coded) point cloud data with view position and angle dependent processing of point cloud data (herein "V-PCC") for 6-DOF media capture / generation / (de)coding / rendering / display. It should be understood that the described features may be used separately or combined in any order, and elements such as encoding and decoding may be implemented by processing circuitry (e.g., one or more processors or one or more integrated circuits), particularly as illustrated, and the one or more processors may execute a program stored on a non-transitory computer-readable medium according to an exemplary embodiment.

[0065] Diagram 600 illustrates an example embodiment for streaming coded point cloud data with V-PCC.

[0066] In volumetric data acquisition block 1101, a real-world visual scene or a computer-generated visual scene (or a combination thereof) may be captured by a set of camera devices or may be synthesized by a computer as volumetric data, and the volumetric data, which may have any format, may be converted to a (quantized) point cloud data format via image processing in conversion to point cloud block 1102. For example, data from the volumetric data may be converted area data by area data into one of the points of the point cloud by pulling one or more of the values ​​described below from the volumetric data and any associated data into the desired point cloud format, according to an exemplary embodiment. According to an exemplary embodiment, the volumetric data may be a 3D dataset of a 2D image, such as a slice from which a 2D projection of the 3D dataset may be projected. According to an example embodiment, a point cloud data format includes a representation of data points in one or more various spaces and may be used to represent volumetric data and may provide improvements with respect to sampling and data compression with respect to temporal redundancy, etc. For example, point cloud data in an x, y, z format may represent color values ​​(e.g., RGB, etc.), brightness, intensity, etc. at each point of a plurality of points of cloud data and may be used with progressive decoding, polygon meshes, direct rendering, octree 3D representations of 2D quadtree data.

[0067] In a projection to image block 1103, the acquired point cloud data may be projected to a 2D image and encoded as an image / video picture using video-based point cloud coding (V-PCC). The projected point cloud data may consist of attributes, geometry, occupancy maps, and other metadata used for point cloud data reconstruction using, for example, Painter's algorithm, ray casting algorithms, (3D) binary space partitioning algorithms, among others.

[0068] Meanwhile, in the scene generator block 1109, the scene generator may generate some metadata used to render and display 6 degrees of freedom (DoF) media, for example, according to the director's intent or user preferences. Such 6DoF media may include 360VR like 3D view of the scene from rotational changes on 3D axes X, Y, Z, in addition to additional dimensions that allow for forward / backward, up / down, and left / right movement within the point cloud coded data or at least for the virtual experience according to it. The scene description metadata defines one or more scenes composed of the coded point cloud data and other media data including VR360, light field, audio, etc., and may be provided to one or more cloud servers and / or file / segment encapsulation / deencapsulation processes as shown in FIG. 6 and related description.

[0069] After a video encoding block 1104 and an image encoding block 1105 similar to the video and image encoding described above (it will be appreciated that audio encoding may also be provided as described above), a file / segment encapsulation block 1106 processes the coded point cloud data to be composed into media files for file playback, or a sequence of initialization segments, and media segments for streaming according to a particular media container file format, such as one or more video container formats, among others, such descriptions may be used in connection with DASH, described below, such as representing an exemplary embodiment. The file container may also include scene description metadata, such as from a scene generator block 1109, in the files or segments.

[0070] According to an exemplary embodiment, a file includes at least one view position and at least one or more angular views at the view position(s) at one or more times of the 6DoF media, encapsulated according to scene description metadata such that such a file may be transmitted on request according to user or creator input. Further, according to an exemplary embodiment, a segment of such a file may include one or more portions of such a file, e.g., a portion of the 6DoF media showing one viewpoint and an angle at one or more times, although these are merely exemplary embodiments and may be changed according to various conditions such as network, user, creator capabilities and input.

[0071] According to an example embodiment, the point cloud data is partitioned into multiple 2D / 3D regions that are coded independently, such as in one or more of the video encoding block 1104 and the image encoding block 1105. Each independently coded partition of the point cloud data may then be encapsulated as a file and / or a segment track in the file / segment encapsulation block 1106. According to an example embodiment, each point cloud track and / or metadata track may include some useful metadata for view position / angle dependent processing.

[0072] According to an example embodiment, metadata useful for view position / angle dependent processing, such as included in files and / or segments encapsulated with respect to a file / segment encapsulation block, includes one or more of the following: layout information of 2D / 3D partitions with indexes; (dynamic) mapping information associating a 3D volume partition with one or more 2D partitions (e.g., tiles / tile groups / slices / subpictures); 3D position of each 3D partition on the 6DoF coordinate system; a representative view position / angle list; a selected view position / angle list corresponding to the 3D volume partition; an index of the 2D / 3D partition corresponding to the selected view position / angle; quality (rank) information of each 2D / 3D partition; and rendering information of each 2D / 3D partition according to, for example, each view position / angle. Invoking such metadata when requested, such as by a user of the V-PCC player or as directed by a content creator on behalf of a user of the V-PCC player, may enable more efficient processing with respect to the particular portion of the 6DoF media that is desired with respect to such metadata, such that the V-PCC player may deliver a higher quality image that is focused on that portion of the 6DoF media more than other portions, rather than delivering unused portions of that media.

[0073] From the File / Segment Encapsulation block 1106, the file or one or more segments of the file can be delivered directly to either the V-PCC Player 1125 and a cloud server such as the Cloud Server block 1107 using a delivery mechanism (e.g., Dynamic Adaptive Streaming over HTTP (DASH)), which can extract one or more tracks and / or one or more specific 2D / 3D partitions from the file and can merge multiple coded point cloud data into one data.

[0074] If the current view position and angle is defined in the 6DoF coordinate system at the client system, according to data such as position / view angle tracking block 1108, then in the cloud server block 1107, the view position / angle metadata may be delivered from the file / segment encapsulation block 1106 or otherwise processed from files or segments already on the cloud server, so that the cloud server may extract the appropriate partitions from the store files and merge them (if necessary) depending on the metadata, for example from a client system having a V-PCC player 1125, and the extracted data can be delivered to the client as files or segments.

[0075] For such data, in file / segment decapsulation block 1115, a file decapsulator processes the file or received segment, extracts the coded bitstream and parses the metadata, and in video decoding and image decoding block the coded point cloud data is then decoded and reconstructed into point cloud data in point cloud reconstruction block 1112, which can be displayed in display block 1114 and / or may be initially configured in response to one or more various scene descriptions in scene composition block 1113 for scene description data by scene generator block 1109.

[0076] In view of the above, such an exemplary V-PCC flow represents advantages over the V-PCC standard including one or more of the described partitioning capabilities for multiple 2D / 3D areas, the capability of compressed domain assembly of coded 2D / 3D partitions into a single conforming coded video bitstream, and the capability of coded 2D / 3D bitstream extraction of coded pictures into a conforming coded bitstream, such V-PCC system support being further improved by including a container formation for a VVC bitstream to support a metadata-containing mechanism for carrying one or more of the above-mentioned metadata.

[0077] In that regard, according to an exemplary embodiment described further below, the term "mesh" refers to a composition of one or more polygons that represent the surface of a volumetric object. Each polygon is defined by its vertices in 3D space and information on how the vertices are connected, referred to as connectivity information. Optionally, vertex attributes such as color, normal, etc. can be associated with the mesh vertices. Attributes can also be associated with the surface of the mesh by utilizing mapping information that parametrizes the mesh with a 2D attribute map. Such mapping can be described by a set of parametric coordinates, called UV coordinates or texture coordinates, associated with the mesh vertices. The 2D attribute map (referred to as a texture map in some instances) is used to store high-resolution attribute information such as texture, normal, displacement, etc. Such information can be used for various purposes such as texture mapping and shading.

[0078] Nevertheless, dynamic mesh sequences may require a large amount of data since it may consist of a significant amount of information that changes over time. Therefore, efficient compression techniques are needed to store and transmit such content. Mesh compression standards IC, MESHGRID, FAMC were previously developed by MPEG to address dynamic meshes with always-on connectivity and time-varying geometry and vertex attributes. However, these standards do not consider time-varying attribute maps and connectivity information. DCC (Digital Content Creation) tools typically generate such dynamic meshes. Correspondingly, it is difficult for volumetric acquisition techniques to generate always-on connectivity dynamic meshes, especially under real-time constraints. This type of content is not supported by existing standards. According to exemplary embodiments herein, aspects of a new mesh compression standard are described to directly handle dynamic meshes with time-varying connectivity information and optionally time-varying attribute maps, which targets lossy and lossless compression for various applications such as real-time communication, storage, free viewpoint video, AR and VR. Features such as random access and scalable / progressive coding are also considered. A "mesh", or "input mesh", etc., is data for a number of at least two vertices.

[0079] FIG. 7 represents one dynamic mesh compression example framework 700 for 2D atlas sampling based methods, etc. Each frame of the input mesh 1201 can be pre-processed by a series of operations such as tracking, remeshing, parameterization, voxelization, etc. It should be noted that these operations can be encoder only, meaning that they may not be part of the decoding process, and such a possibility can be signaled in the metadata by a flag such as 0 indicating only to the encoder and 1 indicating elsewhere. Then, a mesh 1202 with a 2D UV atlas can be obtained, in which each vertex of the mesh has one or more associated UV coordinates of the 2D atlas. The mesh can then be converted into multiple maps, including geometry maps and attribute maps, by sampling with the 2D atlas. These 2D maps can then be coded by a video / image codec such as HEVC, VVC, AV1, AVS3, etc. At the decoder 1203 side, a mesh can be reconstructed from the decoded 2D maps. Any post-processing and filtering can also be applied to the reconstructed mesh 1204. Note that other metadata may be signaled to the decoder side for the purpose of 3D mesh reconstruction. Note that chart boundary information, including uv and xyz coordinates of boundary vertices, can be predicted, quantized, and entropy coded in the bitstream. The quantization step size can be configured on the encoder side for a tradeoff between quality and bitrate.

[0080] In some implementations, a 3D mesh can be partitioned into several segments (or patches / charts). Each segment consists of a set of connected vertices associated with their geometry, attributes, and connectivity information. As shown in the volumetric data example 800 in FIG. 8, a UV parameterization process 1302 that maps 3D mesh segments to 2D charts, such as the 2D UV atlas 1202 block described above, maps one or more mesh segments 1301 to a 2D chart 1303 in the 2D UV atlas 1304. Each vertex (v n ) are assigned 2D UV coordinates in the 2D UV atlas. n Note that vertices v , v ... 4 is the vertex v 0 ,v 5 ,v 1 ,v 3 , and information about each of the other vertices may be similarly shown. Furthermore, such a 2D texture mesh, according to an exemplary embodiment, may also include information such as color information for each triangular patch, e.g., v 2 ,v 5 ,v 3 Further details will be provided for each patch.

[0081] For example, see example 900 of FIG. 9, where, in addition to the features of example 800 of FIG. 8, a 3D mesh segment 1301 can also be mapped to multiple separate 2D charts 1401 and 1402. In this case, a 3D vertex can correspond to multiple vertices in the 2D UV atlas. As shown in FIG. 9, the same 3D mesh segment is mapped to multiple 2D charts in the 2D UV atlas, instead of a single chart as in FIG. 8. For example, a 3D vertex v 1 and v 4 are two 2D correspondences v 1 ,v1’ and v 4 ,v 4’ Thus, a typical 2D UV atlas of a 3D mesh may be composed of multiple charts as shown in Fig. 14, where each chart may contain multiple vertices (usually three or more) associated with their 3D geometry, attributes, and connectivity information.

[0082] Figure 10 shows the boundary vertex B 0 ,B 1 ,B 2 ,B 3 ,B 4 ,B 5 ,B 6 ,B 7 10 shows an example 1000 illustrating a derived triangulation in a chart having the following characteristics: When such information is presented, any triangulation can be applied to create connectivity between vertices (including boundary vertices and sampled vertices). For example, for each vertex, find the two closest vertices. Or, for every vertex, generate triangles successively until a minimum number of triangles is achieved after a set number of attempts. As shown in the example 1000, there are various regular shaped repeating triangles and various irregular shaped triangles, which are generally closest to the boundary vertices and have their own dimensions that may or may not be shared with other triangles. The connectivity information can also be reconstructed by explicit signaling. If the polygon cannot be restored by implicit rules, the encoder can signal the connectivity information in the bitstream according to an exemplary embodiment.

[0083] Looking at the above patch, the example 1000 is a patch that is created by vertex v 3 , v 2 , v 5 may represent one such patch, such as a patch formed from

[0084] Boundary vertex B 0 ,B 1 ,B 2 ,B 3 ,B 4 ,B5 ,B 6 ,B 7 is defined in 2D UV space. As shown in Fig. 15, a filled vertex is a border vertex because it is on the border edge of a connected component (patch / chart). A border edge can be determined by checking if the edge appears in only one triangle. The following information of a border vertex is important and should be signaled in the bitstream according to an exemplary embodiment: the information is geometry information, e.g., 3D XYZ coordinates even if currently in 2D UV parametric form, and 2D UV coordinates.

[0085] As shown in Figure 9, if a 3D bounding vertex corresponds to multiple vertices in the 2D UV atlas, the mapping from 3D XYZ to 2D UV can be one-to-many. Therefore, a UV-to-XYZ (or called UV2XYZ) index can be signaled to indicate the mapping function. UV2XYZ may be a 1D array of indices that maps each 2D UV vertex to a 3D XYZ vertex.

[0086] According to an exemplary embodiment, to efficiently represent a mesh signal, a subset of mesh vertices may be first coded along with connectivity information between them. In the original mesh, connections between these vertices may not exist due to sub-sampling from the original mesh. There are various ways to signal connectivity information between vertices, and thus such a subset is referred to as a base mesh or base vertices.

[0087] However, other vertices can be predicted by applying interpolation between two or more already decoded mesh vertices. Since a predictor vertex has its geometric location along the edges of two connected existing vertices, the geometric information of the predictor can be calculated based on the nearby decoded vertices. In some cases, a displacement vector or a prediction error from the vertex to be coded to the vertex predictor should be further coded. For example, referring to example 1100 of FIG. 11, an example of such an edge-based vertex prediction is shown, more specifically, an example of vertex geometry prediction using extrapolation by extending a triangle into a parallelogram as shown on the left, and intra-prediction by interpolation by weighted average of two existing vertices as shown on the right. After decoding the base vertices (i.e., the solid triangles 1801 on the left side of FIG. 11), the interpolation between these base vertices can be performed along the connected edges. For example, the midpoints of each edge can be generated as predictors. The geometric location of these interpolated points is therefore the (weighted) average of the two nearby decoded vertices (dashed points 1802 on the left side of FIG. 11). Having multiple intermediate points between two already decoded vertices can also be done in a similar way. Thus, the actual vertices to be coded can be reconstructed by adding the displacement vectors to the predictors (Fig. 7 center). After decoding these additional vertices, the connections between the newly decoded vertices and the existing base vertices are still maintained. Furthermore, more connections between the newly decoded vertices can be established. More intermediate vertex predictors can be generated along new edges (Fig. 7 right) by connecting these newly decoded vertices 1803 together with the base vertex. Thus, there are more actual vertices to be decoded with associated displacement vectors.

[0088] According to an example embodiment, mesh vertices of mesh frame 1902 can also be predicted from decoded vertices of previously coded mesh frame 1901. This prediction mechanism is called inter prediction. An example of mesh geometry inter prediction is shown in example 1200 of FIG. 12, which shows vertex geometry prediction using inter prediction (vertices of a previous mesh frame become predictors of vertices of a current frame). In some cases, a displacement vector or a prediction error from the vertex to be coded to the vertex predictor should also be coded.

[0089] According to an exemplary embodiment, several methods are implemented for dynamic mesh compression, which are part of the edge-based vertex prediction framework described above, where a base mesh is first coded and then more additional vertices are predicted based on connectivity information from the edges of the base mesh. It should be noted that the methods may be applied individually or in any form of combination.

[0090] Consider, for example, the flowchart 1300 of an example of vertex grouping for prediction modes in FIG. 13. In S201, vertices in a mesh may be obtained and in S202, they may be divided into different groups for prediction purposes, see, for example, FIG. 10. In one example, the division is performed using patch / chart partitioning in S204 as described above. In another example, the division is performed under each patch / chart S205. The decision S203 to proceed to S204 or S205 may be signaled by a flag or the like. For S205, some vertices of the same patch / chart form a prediction group and share the same prediction mode, while some other vertices of the same patch / chart may use other prediction modes. Such grouping in S206 may be assigned at different levels by determining the respective number of vertices included per group. For example, every 64, 32, or 16 vertices following the scanning order in the patch / chart may be assigned the same prediction mode according to an exemplary embodiment, and other vertices may be assigned differently. For each group, the prediction mode can be an intra prediction mode or an inter prediction mode. This can be signaled or assigned. According to the example flowchart 1300, if the mesh frame or mesh slice is determined to be an intra type at S207, such as by checking whether a flag of the mesh frame or mesh slice indicates an intra type, all vertex groups in the mesh frame or mesh slice shall use an intra prediction mode; otherwise, at S208, either the intra prediction mode or the inter prediction mode may be selected per group for all vertices therein.

[0091] Furthermore, for a group of mesh vertices using intra prediction mode, the vertices can only be predicted by using previously coded vertices in the same subpartition of the current mesh. Sometimes, the subpartition can be the current mesh itself according to an exemplary embodiment, and for a group of mesh vertices using inter prediction mode, the vertices can only be predicted by using previously coded vertices from other mesh frames according to an exemplary embodiment. Each of the above information can be determined and signaled by a flag or the like. The prediction feature may occur in S210, and the result of the prediction and signaling may occur in S211.

[0092] According to an exemplary embodiment, for each vertex in the group of vertices of the exemplary flowchart 1300 and the flowchart 1400 described below, after prediction, the residual becomes a 3D displacement vector indicating the shift from the current vertex to its predictor. The residual of the group of vertices needs to be further compressed. In one example, the transformation in S211 can be applied to the residual of the vertex group before entropy coding, together with its signaling. To handle the coding of the group of displacement vectors, the following methods can be implemented. For example, one method appropriately signals the group of displacement vectors, some displacement vectors, or cases where its components have only zero values. In another embodiment, a flag is signaled for each displacement vector whether this vector has a non-zero component, and if not, the coding of all components of this displacement vector can be skipped. Furthermore, in another embodiment, a flag is signaled for each group of displacement vector whether this group has a non-zero vector, and if not, the coding of all displacement vectors of this group can be skipped. Further, in other embodiments, a flag is signaled for each component of a group of displacement vectors whether this component of the group has any non-zero vectors, and if not, the coding of this component of all displacement vectors of this group can be skipped. Further, in other embodiments, there may be signaling if a group of displacement vectors or a component of a group of displacement vectors requires a transform, and if not, the transform can be skipped and quantization / entropy coding can be applied directly to the group or group component. Further, in other embodiments, a flag may be signaled for each group of displacement vectors whether this group needs to undergo a transform, and if not, the transform coding of all displacement vectors of this group can be skipped.Furthermore, in other embodiments, a flag is signaled for each component of a group of displacement vectors whether this component of the group needs to undergo a transform, and if not, the transform coding of this component of all displacement vectors of this group can be skipped. The above-mentioned embodiments in this paragraph regarding the processing of vertex prediction residuals can also be performed in combination in parallel on different patches, respectively.

[0093] FIG. 14 shows an exemplary flowchart 1400, in which a mesh frame can be coded and obtained as an entire data unit at S221, meaning that all vertices or attributes of a mesh frame may have correlation between them. Alternatively, depending on the decision at S222, the mesh frame can be divided into smaller independent subpartitions at S223, in a similar concept to slices or tiles of a 2D video or image. The coded mesh frame or coded mesh subpartition can be assigned a prediction type at S224. Possible prediction types include intra-coding type and inter-coding type. For the intra-coding type, only prediction from a reconstructed part of the same frame or slice is allowed at S225. Meanwhile, the inter-prediction type allows prediction from a previously coded mesh frame in addition to the intra-mesh frame prediction at S225. Also, the inter-prediction type may be classified into more subtypes, such as P type and B type. In the P type, only one predictor can be used for prediction purposes, and in the B type, two predictors from two previously coded mesh frames may be used to generate a predictor. A weighted average of two predictors can be an example. When a mesh frame is coded as a whole, the frame can be considered as an intra-coded or inter-coded mesh frame. For an inter-mesh frame, the P or B type can be further identified via signaling. Alternatively, when a mesh frame is further divided and coded within a frame, a prediction type for each sub-partition is assigned in S224. Each of the above information may be determined and signaled by a flag or the like, and the prediction feature may occur in S226, and the result of the prediction and signaling may occur in S227, similar to S210 and S211 in FIG. 13.

[0094] Thus, dynamic mesh sequences may consist of a significant amount of information that changes over time and therefore may require large amounts of data, but efficient compression techniques are needed to store and transmit such content, and the features described above with respect to Figures 20 and 21 represent such improved efficiency by enabling at least improved mesh vertex 3D position prediction by using either previously decoded vertices within the same mesh frame (intra prediction) or previously decoded vertices from a previously coded mesh frame (inter prediction).

[0095] Further, the exemplary embodiment may generate displacement vectors of a third layer 2303 of the mesh based on one or more of the reconstructed vertices of the second layer 2302 and its previous layer(s), such as the first layer 2301. Assuming that the index of the second layer 2302 is T, a predictor T+1 of a vertex of the third layer 2303 is generated based on at least the reconstructed vertices of the current layer or the second layer 2302. An example of such a layer-based prediction structure is shown in the example 1600 of FIG. 16, which illustrates reconstruction-based vertex prediction, i.e., progressive vertex prediction using edge-based interpolation, where a predictor is generated based on previously decoded vertices rather than predictor vertices. The first layer 2301 may be a mesh bounded by a first polygon 2340 having as its vertices the decoded vertices on its boundary and the interpolated vertices along one of the lines between those decoded vertices. As the progressive coding proceeds from the first layer 2301 to the second layer 2302, an additional polygon 2341 may be formed by a displacement vector from one of the interpolated vertices of the first layer to an additional vertex of the second layer 2302, so that the total number of vertices of the second layer 2302 may be greater than the total number of vertices of the first layer 2301. Similarly, when proceeding to the third layer 2303, the additional vertices of the second layer 2302 together with the decoded vertices from the first layer 2301 may function in the coding in the same way as the decoded vertices provided when proceeding from the first layer 2301 to the second layer 2303, i.e., multiple additional polygons may be formed. As a note, referring to example 1900 of Figure 19 illustrating such progressive coding, unlike Figure 16, example 1900 shows that when moving from the first layer 2601 to the second layer 2603 and then to the third layer 2603, each of the additionally formed polygons may be entirely within the polygon formed by the boundary of the first layer 2601.

[0096] For such an example 1600, referring to the exemplary flowchart 1500 of FIG. 15, since the interpolated vertices of the current layer are predicted values, such values ​​need to be reconstructed before being used to generate predictors for vertices of the next layer. This is done by coding a base mesh in S231, performing vertex prediction in S232, and then adding the decoded displacement vectors of the current layer to the predictors of vertices of layer 2302, etc. in S233. The reconstructed vertices of this layer 2303 can then be used to generate and signal predictor vertices of the next layer 2303 in S235, along with all the decoded vertices of the previous layer(s), such as checking the additional vertex values ​​of such layer in S234. This process can also be summarized as follows: Let P[t](Vi) denote the predictor of vertex Vi on layer t, let R[t](Vi) denote the reconstructed vertex Vi on layer t, let D[t](Vi) denote the displacement vector of vertex Vi on layer t, and let f(*) denote the predictor generator, which may in particular be the average of two existing vertices. Then, for each layer t, according to an exemplary embodiment, there is: P[t](Vi)=f(R[s|s <t](Vj)、R[m|m<t](Vk)) where Vj and Vk are the reconstructed vertices of the previous layer. R[t](Vi)=P[t](Vi)+D[t](Vi) Equation (1)

[0097] Then, for all vertices in one mesh frame, we split them into layer 0 (base mesh), layer 1, layer 2, .... etc. Then, the reconstruction of vertices in one layer depends on the reconstruction of vertices in the previous layer. In the above, each of P, R and D represents a 3D vector under the context of a 3D mesh representation. D is the decoded displacement vector, and quantization may or may not be applied to this vector.

[0098] According to an exemplary embodiment, vertex prediction using reconstructed vertices may only be applied to certain layers. For example, layer 0 and layer 1. For other layers, vertex prediction can still use nearby predictor vertices without adding displacement vectors to them for reconstruction. Therefore, these other layers can be processed simultaneously without waiting for the previous layer to reconstruct. According to an exemplary embodiment, for each layer, it can be signaled whether to select reconstruction-based vertex prediction or predictor-based vertex prediction, or a layer (and its subsequent layers) that does not use reconstruction-based vertex prediction can be signaled.

[0099] For displacement vectors generated by vertices whose vertex predictors are reconstructed, quantization can be applied to them without further performing a transform such as a wavelet transform. For displacement vectors whose vertex predictors are generated by other predictor vertices, a transform may be required and quantization can be applied to the transform coefficients of those displacement vectors.

[0100] Thus, dynamic mesh sequences may require a large amount of data since they may consist of a significant amount of information that changes over time. Therefore, efficient compression techniques are needed to store and transmit such content. In the framework of the interpolation-based vertex prediction method described above, compressing the displacement vectors is one of the key steps, which constitutes a large portion of the coded bitstream and is the focus of this disclosure; for example, the features of FIG. 15 alleviate such problems by providing such compression.

[0101] Moreover, as with the other examples discussed above, even those embodiments may still require a large amount of data since dynamic mesh sequences may consist of a significant amount of information that changes over time, and thus efficient compression techniques are needed to store and transmit such content. In the framework of the 2D atlas sampling based method described above, important advantages can be achieved by inferring connectivity information from sampled vertices and boundary vertices at the decoder side. This is a major part of the decoding process and is the focus of further examples described below.

[0102] According to an exemplary embodiment, the connectivity information of the base mesh can be inferred (derived) from the decoded boundary vertices and sampled vertices of each chart on both the encoder and decoder sides.

[0103] Similar to that described above, any triangulation can be applied to create connectivity between vertices (including boundary vertices and sampled vertices). For charts without sampling of any of the interior vertices, such as those shown in example 1000 of FIG. 10 and example 1800 of FIG. 18 described further below, a similar method of creating connectivity still applies, but according to an example embodiment, different triangulation methods may be signaled to be used for boundary vertices and sampled vertices.

[0104] For example, according to an exemplary embodiment, for every four neighboring points at any sampled location, it may be determined whether the number of occupied points is three or more (examples of occupied or unoccupied points are highlighted in FIG. 18 showing an example occupancy map 1800 where each circle represents an integer number of pixels), and the triangular connectivity between the four points can be inferred by a certain rule. For example, as shown in example 1700 of FIG. 17, if three out of the four points are determined to be occupied, which are the illustrated examples (2), (3), (4), and (4), then the points can be directly interconnected to form a triangle as in the example, whereas if all four points are determined to be occupied, then the points are used to form two triangles as shown in example (1) of FIG. 17. It should be noted that different rules can be applied to different numbers of neighboring points. This process can be carried out across many points, as further shown in FIG. 18. In this embodiment, the reconstructed mesh is a triangular mesh as in FIG. 17, which cannot be determined to be signaled according to such rules, at least as the internal regular triangular mesh of FIG. 18 is, and instead can be coded and decoded by inference rather than individual signaling, and as surrounding irregular triangles signaled individually.

[0105] Also, in an attempt to further reduce complexity and data processing, such a regular interior triangular quad mesh shown in FIG. 18 may be inferred as such a quad mesh of example (1) of FIG. 17, thereby reducing even the degree of complexity of inferring interior regular triangles and inferring a reduced number of interior regular quad meshes instead.

[0106] According to an example embodiment, if all four neighboring points are determined to be occupied, such as in example (1) of FIG. 17, a quadrilateral mesh may be reconstructed.

[0107] Extrapolating from the above description, it is shown that the reconstructed mesh of example 1800, as shown in FIG. 18, may be of a hybrid type, i.e., some regions of the mesh frame generate triangular meshes and other regions generate quadrilateral meshes, some of which may be regular compared to other triangular meshes therein, and some may be irregular, such as one of the boundaries, but not necessarily all of the boundaries of such meshes.

[0108] According to an example embodiment, such connectivity type can be signaled in a high level syntax such as a sequence header or slice header.

[0109] As mentioned above, connectivity information can also be reconstructed by explicit signaling, such as for irregularly shaped triangular meshes. That is, if it is determined that the polygon cannot be restored by implicit rules, the encoder can signal connectivity information in the bitstream. Also, according to an exemplary embodiment, the overhead of such explicit signaling can be reduced depending on the polygon boundary. For example, as shown in the example 1800 of FIG. 18, the connectivity information of a triangle is signaled to be reconstructed by both implicit rules, such as the regular example 2400 of FIG. 17, which can be inferred, and explicit signaling of at least one of the irregularly shaped polygons shown in the mesh boundary of FIG. 18.

[0110] According to an embodiment, it is decided that only connectivity information between boundary vertices and sampled locations is to be signaled, and connectivity information between the sampled locations themselves is inferred.

[0111] Also, in any of the embodiments, connectivity information may be signaled by prediction, such that only the difference from the estimated connectivity (as a prediction) from one mesh to another may be signaled in the bitstream.

[0112] As a note, the inferred triangle orientation (e.g., inferred clockwise or counterclockwise for each triangle) can be signaled for all charts in a high-level syntax such as a sequence header or slice header, or fixed (assumed) by the encoder and decoder according to an example embodiment. The inferred triangle orientation can also be signaled differently for each chart.

[0113] As a further note, any reconstructed mesh may have a different connectivity than the original mesh, for example, the original mesh may be a triangle mesh and the reconstructed mesh may be a polygon mesh (e.g., a quad mesh).

[0114] According to an exemplary embodiment, the connectivity information of any base vertices may not be signaled, and instead the edges between the base vertices may be derived using the same algorithm at both the encoder and decoder sides. See, for example, how the bottom-most vertices in example 1800 are all occupied, whereby coding can utilize such information by determining that such vertices are therefore occupied as bases, and thereby later inferring that the connectivity information of any base vertices may not be signaled, and instead the edges between the base vertices may be derived using the same algorithm at both the encoder and decoder sides. Also, according to an exemplary embodiment, the interpolation of predicted vertices of additional mesh vertices may be based on the derived edges of the base mesh.

[0115] According to an exemplary embodiment, a flag may be used to signal whether the connectivity information of the base vertices should be signaled or derived, and such a flag can be signaled at different levels of the bitstream, such as at the sequence level or the frame level.

[0116] According to an exemplary embodiment, the edges between the base vertices are first derived using the same algorithm on both the encoder and decoder sides.Then, the difference between the derived edges and the actual edges is signaled compared with the original connectivity of the base mesh vertices.Thus, after decoding the difference, the original connectivity of the base vertices can be restored.

[0117] In one example, for derived edges, if they are determined to be erroneous when compared to the original edges, such information may be signaled in the bitstream (by indicating the pair of vertices that form this edge), and for original edges, if they are not derived, they may be signaled in the bitstream (by indicating the pair of vertices that form this edge). Furthermore, vertex interpolation involving connectivity on and to boundary edges may be performed separately from interior vertices and edges.

[0118] Thus, by way of the exemplary embodiments described herein, the technical problems noted above may be advantageously ameliorated by one or more of these technical solutions. For example, dynamic mesh sequences may require large amounts of data, as they may consist of a significant amount of information that changes over time, and thus the exemplary embodiments described herein represent at least an efficient compression technique for storing and transmitting such content.

[0119] The above-described embodiment may further be applied to instance-based mesh coding, where an instance may be a mesh of an object or a part of an object. For example, the illustrated example 2100 of FIG. 21 shows an example mesh 2801, where various instances 2802 (representing a mesh of a cup), 2803 (representing a mesh of a spoon), and 2804 (representing a mesh of a plate) exist and may be separated and coded, respectively. Also, while each of the instances 2801, 2802, 2803, and 2804 are shown in respective bounding boxes, which will be further described below, it should be noted that the instance 2801 may be considered to be shown bounded by a "mesh-based bounding box", and each of the instances 2802, 2803, and 2804 may be considered to be shown bounded by a respective "instance-based bounding box".

[0120] According to an exemplary embodiment, the proposed methods may be used separately or combined in any order. The proposed methods may be used for any polygon mesh, but only triangular meshes may be used to demonstrate the various embodiments. As mentioned above, it is assumed that an input mesh may contain one or more instances, and a sub-mesh is a portion of an input mesh that has one or more instances, and multiple instances may be grouped to form a sub-mesh.

[0121] In that regard, Figure 20 shows an example 2000 in which it is proposed to separately quantize different objects or parts at a given input bit depth (which bit depth may be referred to as "QP"). For example, at 2701, one or more input meshes are obtained, each of which may be separated into multiple sub-meshes. The sub-meshes may be objects, instances of objects, or segmented regions, which are independently quantized at S2702 according to an exemplary embodiment.

[0122] According to an example embodiment, a mesh M having m points at (x, y, z) coordinates may be quantized by the QP bit depth at S2702. The quantization step size in all three dimensions (x, y, z) may be determined based on the maximum length of the bounding box in all dimensions, d bbox >0. Also, the same quantization step size may be applied in S2704 to all objects in the mesh identified in S2703 as follows:

number

number

number

number

number

[0123] However, in complex scenes, the largest objects are the background, which may be relatively simple in many cases and can tolerate higher quantization step sizes, while the main objects are smaller and suffer from large quantization errors that can be accounted for by various embodiments described further below.

[0124] Therefore, as shown in the example 2200 of FIG. 22, the bounding box d bbox The maximum length of is always the same for each instance, as follows:

number

number

number

[0125] For a given bit depth QP, the quantization step size of each instance of instance 2802 (representing a mesh of a cup), 2803 (representing a mesh of a spoon), and 2804 (representing a mesh of a plate) is always

number

[0126] Therefore, the quantization error for each instance is smaller, and the overall quantization error is smaller.

[0127] According to various embodiments, the bit depth may be adaptively assigned to each instance / region, called a "sub-mesh," in S2902 and may be determined based on the areal density of that particular instance. Each sub-mesh may be obtained from the volumetric data of the mesh, which itself may signal each instance in the mesh individually, and each sub-mesh is derived from that mesh on an instance-by-instance basis in S2902. For example, each of instances 2802, 2803, and 2804 may be assigned its own respective bit depth in S2904 according to its own particular areal density or number of vertices forming therein one or more of the aforementioned polygons. In general, the more faces each instance has, which may be determined by counting the number of such polygons therein, etc., in S2903, the less quantization should be applied to that instance in S2702. For example, given a mesh M, the total number of faces is n, and the faces corresponding to the kth sub-mesh are n such that k and

number

number

number

number

[0128] According to various embodiments, the meshes are represented as a base mesh B and its corresponding displacement D, which are quantized at different bit depths in S2702. For example, for the kth object, the bit depths of the base mesh B and its corresponding displacement D are

number

number

number

[0129] According to various embodiments, an adaptive bit depth parameter based on minimizing distortion may be used. For example, given an input bit depth QP, the mean square error (MSE) of the quantization method is ε_QP, which may be as in equation (4). The MSE of each sub-mesh is derived as ε_QP̂k=ω_k*ε_QP,∀k∈[1,...,K], where ω_k>0 is a weighting factor. In one example, ω_k=1∀k. A linear search is performed for each sub-mesh to find the best bit depth of the base mesh that satisfies:

number

[0130] In addition, the best bit depth for the displacement can also be obtained via:

number

[0131] According to an example embodiment, there may be signaling of the quantization of each object, such as by signaling the bit depth via the bit stream in the signal of S2907. The set of base quantization bit depths in ascending order is:

number

number

[0132] [Table 1]

[0133] Where: - u(n) is an unsigned integer using n bits, i(n) is an integer using n bits, and mips_quant() is a sequence of signaling data. -mips_min_bbox[k] is the minimum of the bounding box in the i-th dimension, -mips_num_instances_minus1 is the number of instances in the mesh minus 1 -mips_base_bitdepth_minus1 is the bit depth of the first instance in this order, -mips_base_quant[k] is the difference between the quantization of the k+1th and the kth submesh. If the quantization set is sorted in ascending order, this number is always non-negative. -mips_dist_quant[k] is the kth quantization data for the bit depth of the base mesh.

[0134] According to various embodiments, to reduce signaling overhead, multiple instances may be grouped into K groups with the same bit depth. The instances are clustered by a bounding box using a simple clustering method such as K-means clustering.

number

[0135] However, because such 3D scenes may often consist of multiple instances with similar mesh structures that reuse assets, further improvements may be realized by not only taking advantage of local characteristics but also by considering similarities between instances in accordance with exemplary embodiments.

[0136] For example, FIG. 23 shows an exemplary flowchart 2300 in which an instance-based matching prediction (IMP) method is used to find redundant meshes and encode the corresponding displacements, which may advantageously normalize the instances to maximize their similarity and may be used in any of the embodiments described above.

[0137] For example, in S2801, an input mesh may be obtained and partitioned as described above into multiple sub-meshes, which may be instances of individual objects or portions of objects, according to an example embodiment.

[0138] At S2802, there may be a grouping of instances into similarity groups using simple scaling features and similarity measures. For example, according to an embodiment, the instances may be aligned and normalized so that only transient assets can be reused. Scale and orientation information may be signaled over a channel in IMP mode, and given an input mesh M with m instances, the i-th instance may be

number

[0139] According to an exemplary embodiment, in S2803, in response to the instruction of the flag, the IMP is used to select a size greater than 1, i.e., m k > 1 asset group

number

[0140] [Table 2]

[0141] Depending on the flag S2804, the coding in S2805 may be signaled to code the sub-meshes into sub-bitstreams independently. Each sub-mesh can be coded by a mesh codec with different coding parameters. Note that each sub-mesh can also be coded by a different mesh codec, in which case a codec index indicating which mesh codec is used needs to be signaled in the header of the sub-bitstream or the like. According to an exemplary embodiment, the sub-bitstreams of a sub-mesh can be encoded and decoded in parallel without data dependency issues.

[0142] If the flag in S2804 indicates dependent coding instead, an additional flag may be considered in S2806 to indicate also the mode of dependently coding the sub-meshes. For example, according to an embodiment, a sub-mesh may be coded by prediction from other sub-meshes already coded. A prediction index may be coded to indicate which sub-mesh is used as prediction. The prediction index may be signaled at different levels.

[0143] For example, in S2807, only one prediction index may be coded for the entire submesh, so that all vertices in the current submesh are predicted from the same submesh as indicated by the index according to an exemplary embodiment.

[0144] At S2808, a prediction index may be signaled for each vertex of the current submesh so that each vertex can be predicted from a different submesh. Note that the prediction index may also be coded by predictive coding, and the prediction index of a vertex may be predicted from neighboring coded vertices. Then, according to an exemplary embodiment, the prediction index residual may be coded by arithmetic coding.

[0145] In S2809, the prediction index may be signaled at an intermediate level between the vertex level and the sub-mesh level, such as at the vertex group level, where a group of vertices shares the same prediction index, and the prediction indexes of different groups can also be coded by predictive coding according to an exemplary embodiment.

[0146] Next, given the prediction index of each vertex of the current submesh, each vertex can be predicted from the vertices in the corresponding submesh, as described above in any of FIG. 13, FIG. 14, and FIG. 15. According to an exemplary embodiment, a rigid motion may be estimated from the prediction submesh to the current submesh, and the parameters of the rigid motion (e.g., rotation and translation parameters) can be coded. Then, after applying the rigid motion to the prediction submesh, a residual of the attributes of the current vertex can be obtained by subtracting the attributes of the corresponding vertex in the transformed prediction submesh. The attributes of the vertex can include, but are not limited to, geometry, color, normal, uv coordinates, connectivity, etc. Then, the residual information can be coded by arithmetic coding according to an exemplary embodiment.

[0147] Additionally, such coding may be applied to coding of material and texture information per sub-mesh, which may include, but is not necessarily limited to, ambient color, diffuse color, specular color, specular highlight focus, dissolve coefficients, lighting model, texture image ID, etc.

[0148] According to an example embodiment, one sub-mesh only allows one set of material and texture information, and in such a case this information can simply be coded in the header of the sub-bitstream.

[0149] Or, according to an exemplary embodiment, one submesh may have two or more sets of material and texture information, in which case the sets may be coded in the header of the subbitstream. Note that these parameters in different sets may be coded independently or dependently. If dependent coding is applied, prediction may be applied and the prediction residual of the material parameters may be coded instead. Then, for each vertex in the submesh, a material ID may be coded to indicate which set of material information is used for this vertex. Note that according to an exemplary embodiment, in order to reduce redundancy, the material ID (identifier) ​​may be coded by predicting from the coded neighbor vertices.

[0150] Thus, according to embodiments herein, it is realized that complex meshes may often contain information about multiple instances to associate texture maps, and that information may be available at the time of encoding, so that each instance may be considered a 3D asset in 3D design according to exemplary embodiments herein, as the asset may be frequently used to reduce costs in designing models, especially for compositing complex scenes. For example, 3D models may be reused with or without textures modified with differences in scale, orientation, etc. This, among other aspects discussed above, addresses issues related to matching and searching 3D objects, since meshes may be normalized to position, size, and orientation based on PCA (principal component analysis) or bilateral symmetry planes, and thereby more efficiently searched.

[0151] The techniques described above can be implemented using computer readable instructions, as computer software physically stored on one or more computer readable media, or by one or more tangibly configured hardware processors. For example, FIG. 24 illustrates a computer system 2400 suitable for implementing certain embodiments of the disclosed subject matter.

[0152] The computer software can be coded using any suitable machine code or computer language that can be subjected to mechanisms such as assembly, compilation, linking, etc. to create code containing instructions that can be executed by a computer central processing unit (CPU), graphics processing unit (GPU), etc. directly, or via interpretation, microcode execution, etc.

[0153] The instructions may be executed on various types of computers or computer components including, for example, personal computers, tablet computers, servers, smart phones, gaming devices, Internet of Things devices, and the like.

[0154] 24 with respect to computer system 2400 are exemplary in nature and are not intended to suggest any limitation as to the scope of use or functionality of the computer software implementing the embodiments of the present disclosure. The arrangement of components should not be interpreted as having any dependency or requirement regarding any one or combination of components illustrated in the exemplary embodiment of computer system 2400.

[0155] The computer system 2400 may include certain human interface input devices. Such human interface input devices may respond to input by one or more human users, for example, via tactile input (keystrokes, swipes, data glove movements, etc.), audio input (voice, clapping, etc.), visual input (gestures, etc.), olfactory input (not shown). Human interface devices may also be used to capture certain media not necessarily directly associated with conscious human input, such as audio (voice, music, ambient sounds, etc.), images (scanned images, photographic images obtained from still image cameras, etc.), video (two-dimensional video, three-dimensional video including stereoscopic video, etc.).

[0156] The input human interface devices may include one or more of a keyboard 2401, a mouse 2402, a trackpad 2403, a touch screen 2410, a joystick 2405, a microphone 2406, a scanner 2408, a camera 2407 (only one of each is shown).

[0157] The computer system 2400 may also include certain human interface output devices. Such human interface output devices may stimulate one or more of the human user's senses, for example, through haptic output, sound, light, and smell / taste. Such human interface output devices may include haptic output devices (e.g., touch screen 2410, or haptic feedback via joystick 2405, although there may be haptic feedback devices that do not function as input devices), audio output devices (such as speakers 2409, headphones (not shown)), visual output devices (such as screens 2410, including CRT screens, LCD screens, plasma screens, OLED screens, each with or without touch screen input capabilities, each with or without haptic feedback capabilities, some of which may be capable of outputting two-dimensional visual output, or output in more than three dimensions, via means such as stereographic output, virtual reality glasses (not shown), holographic displays, and smoke tanks (not shown)), and printers (not shown).

[0158] The computer system 2400 may also include human accessible storage devices and their associated media, such as CD / DVD 2411 or CD / DVD ROM / RW 2420 with similar media, thumb drives 2422, removable hard drives or solid state drives 2423, legacy magnetic media such as tapes and floppy disks (not shown), optical media including dedicated ROM / ASIC / PLD based devices such as security dongles (not shown), and the like.

[0159] Those skilled in the art should also understand that the term "computer-readable medium" as used in connection with the subject matter of this disclosure does not encompass transmission media, carrier waves, or other transitory signals.

[0160] The computer system 2400 may also include an interface 2499 to one or more communication networks 2498. The network 2498 may be, for example, wireless, wired, optical. The network 2498 may further be local, wide area, metropolitan, vehicular and industrial, real-time, delay tolerant, etc. Examples of networks 2498 include local area networks such as Ethernet, wireless LAN, cellular networks including GSM, 3G, 4G, 5G, LTE, etc., TV wired or wireless wide area digital networks including cable TV, satellite TV, and terrestrial broadcast TV, vehicular and industrial including CANBus, etc. A particular network 2498 generally requires an external network interface adapter attached to a particular general purpose data port or peripheral bus (2450 and 2451) (e.g., USB port of the computer system 2400, etc.), while other networks are generally built into the core of the computer system 2400 by attachment to the system bus as described below (e.g., an Ethernet interface to a PC computer system or a cellular network interface to a smartphone computer system). Using any of these networks 2498, the computer system 2400 can communicate with other entities. Such communications may be one-way receive only (e.g., broadcast TV), one-way transmit only (e.g., CANbus to a particular CANbus device), or two-way, such as to other computer systems using local area or wide area digital networks. Specific protocols and protocol stacks may be used with each of these networks and network interfaces, as described above.

[0161] The aforementioned human interface devices, human accessible storage devices, and network interfaces may be attached to the core 2440 of the computer system 2400.

[0162] The core 2440 may include one or more central processing units (CPUs) 2441, graphics processing units (GPUs) 2442, graphics adapters 2417, dedicated programmable processing units in the form of field programmable gate areas (FPGAs) 2443, hardware accelerators 2444 for specific tasks, etc. These devices may be connected through a system bus 2448, along with read only memory (ROM) 2445, random access memory 2446, internal mass storage 2447 such as an internal non-user accessible hard drive, SSD, etc. In some computer systems, the system bus 2448 may be accessible in the form of one or more physical plugs to allow expansion with additional CPUs, GPUs, etc. Peripheral devices may be attached directly to the core's system bus 2448 or through a peripheral bus 2449. Architectures for peripheral buses include PCI, USB, etc.

[0163] The CPU 2441, GPU 2442, FPGA 2443, and accelerator 2444 can combine to execute certain instructions that may constitute the aforementioned computer code. This computer code may be stored in ROM 2445 or RAM 2446. Transient data may also be stored in RAM 2446, while persistent data may be stored, for example, in internal mass storage 2447. A cache memory, which may be closely associated with one or more of the CPU 2441, GPU 2442, mass storage 2447, ROM 2445, RAM 2446, etc., may be used to enable fast storage and fast retrieval to any of the memory devices.

[0164] The computer-readable medium can bear computer code for performing various computer-implemented operations. The medium and computer code can be those specially designed and constructed for the purposes of the present disclosure, or they can be of the available kind well known to those skilled in the computer software arts.

[0165] By way of example and not limitation, computer system 2400 having the architecture, and specifically core 2440, may provide functionality as a result of a processor (including CPU, GPU, FPGA, accelerator, etc.) executing software embodied in one or more tangible computer-readable media. Such computer-readable media may be user-accessible mass storage as previously described, as well as media associated with specific storage of core 2440 that is non-transitory in nature, such as core internal mass storage 2447 or ROM 2445. Software implementing various embodiments of the present disclosure may be stored in such devices and executed by core 2440. Computer-readable media may include one or more memory devices or chips, depending on the particular needs. The software may cause core 2440, and specifically the processor therein (including CPU, GPU, FPGA, etc.) to perform certain processes or certain parts of certain processes described herein, including defining data structures stored in RAM 2446 and modifying such data structures according to the software-defined processes. Additionally, or alternatively, a computer system may provide functionality as a result of hardwired or otherwise embodied logic in circuitry (e.g., accelerator 2444) that may operate in place of or in conjunction with software to perform certain processes or certain portions of certain processes described herein. Reference to software may encompass logic, and vice versa, where appropriate. Reference to a computer-readable medium may encompass circuitry (such as an integrated circuit (IC)) that stores software for execution, circuitry that embodies logic for execution, or both, where appropriate. The present disclosure encompasses any suitable combination of hardware and software.

[0166] While this disclosure describes several exemplary embodiments, there are alterations, substitutions, and various alternative equivalents that fall within the scope of this disclosure. Thus, it will be appreciated that those skilled in the art will be able to devise numerous systems and methods that, although not explicitly shown or described herein, embody the principles of the present disclosure and are therefore within its spirit and scope. [Explanation of symbols]

[0167] 100 communication system, 101 terminal, 102 second terminal, 103 first terminal, 104 terminal, 105 communication network, 201 video source, 202 encoder, 203 capture subsystem, 204 video bitstream, 205 streaming server, 206 video bitstream, 207 streaming client, 208 video bitstream, incoming copy, 209 display, 210 outgoing video sample stream, 211 video decoder, 212 streaming client, 213 uncompressed video sample stream, 300 video decoder, 301 channel, 302 receiver, 303 buffer memory, 304 entropy decoder / parser, 305 scaler / inverse transform unit, 306 motion compensation prediction unit, 307 intra picture prediction unit, 308 reference picture memory, reference picture buffer, 309 reference picture, 310 aggregator, 311 Loop filter unit, 312 display, rendering device, 313 symbols, 400 video encoder, 401 video source, 402 controller, 403 source coder, 404 predictor, 405 reference picture memory, 406 local video decoder, 407 coding engine, 408 entropy coder, 409 transmitter, 410 coded video sequence, 411 communication channel, 500 simplified block style workflow diagram, 600 simplified block style content flow process diagram, 700 framework, 1001 acquisition block, 1002 audio encoding block, 1003 processing block, 1004 video encoding block, 1005 image encoding block, 1007 distribution block, 1008 eye tracking block, 1010 audio decoding block, 1011 audio rendering block, 1012 headphone block, 1013 video decoding block, 1014 Image decoding block, 1015 image rendering block, 1016 display block, 1020 OMAF player, 1101 volumetric data acquisition block, 1102 transformation block, 1103 projection block, 1104Video encoding block, 1105 Image encoding block, 1106 Segment encapsulation block, 1107 Cloud server block, 1108 View angle tracking block, 1109 Scene generator block, 1112 Point cloud reconstruction block, 1113 Scene composition block, 1114 Display block, 1115 Segment deencapsulation block, 1125 V-PCC player, 1201 Input mesh, 1202 Mesh with 2D UV atlas, 1203 Decoder, 1204 Reconstructed mesh, 1300 Exemplary flow chart, 1301 3D mesh segments, 1302 UV parameterization process, 1303 2D chart, 1304 2D UV atlas, 1400 Exemplary flow chart, 1401 2D chart, 1402 2D chart, 1500 Exemplary flow chart, 1700 Example, 1801 Triangle, 1802 dashed points, 1803 vertices, 1901 mesh frame, 1902 mesh frame, 2300 flow chart, 2301 first layer, 2302 second layer, 2303 third layer, 2340 first polygon, 2341 additional polygon, 2400 computer system, 2401 keyboard, 2402 mouse, 2403 trackpad, 2405 joystick, 2406 microphone, 2407 camera, 2408 scanner, 2409 speaker, 2410 touch screen, 2417 graphics adapter, 2420 CD / DVD ROM / RW, 2421 CD / DVD, 2422 thumb drive, 2423 solid state drive, 2440 core, 2441 central processing unit (CPU), 2442 graphics processing unit (GPU), 2443 Field Programmable Gate Area (FPGA), 2444 hardware accelerator, 2445 read only memory (ROM), 2446 random access memory, 2447 core internal mass storage, 2448 system bus, 2449 peripheral bus, 2450 peripheral bus, 2451 peripheral bus, 2498 communication network, 2499 interface, 2601 first layer, 2602 second layer, 2603 third layer, 2801 instance, 2802Instance, 2803 Instance, 2804 Instance

Claims

1. 1. A method for video decoding, the method being executed by at least one processor, comprising: obtaining an input mesh corresponding to volumetric data for at least one three-dimensional (3D) visual content; partitioning the input mesh corresponding to the volumetric data into a number of sub-meshes, each of the sub-meshes including a respective one of the instances of the object; determining a similarity between at least two of the instances of the object; grouping the plurality of sub-meshes based on the determined similarity; decoding the volumetric data based on the grouping of the plurality of sub-meshes; A method comprising:

2. determining the similarity includes comparing bounding boxes of the at least two of the object instances; A method for video decoding according to claim 1.

3. Comparing the bounding boxes includes comparing ratios of dimensions of the bounding boxes. A method for video decoding according to claim 2.

4. and decoding the volumetric data includes signaling a different one of the codecs to each one of the instances of the at least two objects. A method for video decoding according to claim 1.

5. and decoding the volumetric data includes signaling a prediction of a first one of the at least two object instances based on a prediction of a second one of the at least two object instances. A method for video decoding according to claim 1.

6. and decoding the volumetric data includes signaling only a single prediction index for the entire first one of the at least two object instances. A method for video decoding according to claim 5.

7. and decoding the volumetric data includes signaling only a plurality of prediction indexes for the first of the at least two object instances. A method for video decoding according to claim 5.

8. a first one of the plurality of prediction indexes is based on a first prediction index; a second one of the plurality of prediction indexes is based on a second prediction index; the first predicted index is based on a first other predicted index that is a predicted index of the second one of the instances of the at least two objects; the second one of the plurality of predicted indexes is based on a second other predicted index that is a predicted index of a third one of the instances of the at least two objects. A method for video decoding according to claim 7.

9. signaling a prediction of the first one of the at least two object instances includes signaling a first prediction index and a second prediction index; the first predicted index is a single index collectively set to each of a plurality of vertices of the first one of the instances of the at least two objects; the second predicted index is set to at least one other vertex of the first one of the at least two object instances; A method for video decoding according to claim 5.

10. at least one of the first prediction index and the second prediction index is based on a prediction index set for at least one vertex of the second one of the at least two object instances; A method for video decoding according to claim 10.

11. 1. An apparatus for video decoding, comprising: at least one memory configured to store computer program code; at least one processor configured to access the computer program code and operate as instructed by the computer program code, the computer program code comprising: acquiring code configured to cause the at least one processor to acquire an input mesh comprising volumetric data of at least one three-dimensional (3D) visual content; partitioning code configured to cause the at least one processor to partition the input mesh corresponding to the volumetric data into a plurality of sub-meshes, each of the sub-meshes including a respective one of the instances of an object; and determining code configured to cause the at least one processor to determine a similarity between at least two of the instances of the object; grouping code configured to cause the at least one processor to group the plurality of sub-meshes based on the determined similarities; decoding code configured to cause the at least one processor to code the volumetric data based on the grouping of the plurality of sub-meshes; At least one processor, An apparatus comprising:

12. determining the similarity includes comparing bounding boxes of the at least two object instances; An apparatus for video decoding according to claim 11.

13. Comparing the bounding boxes includes comparing ratios of dimensions of the bounding boxes. An apparatus for video decoding according to claim 12.

14. and decoding the volumetric data includes signaling a different one of the codecs to each one of the instances of the at least two objects. An apparatus for video decoding according to claim 11.

15. and decoding the volumetric data includes signaling a prediction of a first one of the at least two object instances based on a prediction of a second one of the at least two object instances. An apparatus for video decoding according to claim 11.

16. and decoding the volumetric data includes signaling only a single prediction index for the entire first one of the at least two object instances. An apparatus for video decoding according to claim 15.

17. and decoding the volumetric data includes signaling only a plurality of prediction indexes for the first one of the instances of the at least two objects. An apparatus for video decoding according to claim 15.

18. a first one of the plurality of prediction indexes is based on a first prediction index; a second one of the plurality of prediction indexes is based on a second prediction index; the first predicted index is based on a first other predicted index that is a predicted index of the second one of the instances of the at least two objects; the second one of the plurality of predicted indexes is based on a second other predicted index that is a predicted index of a third one of the instances of the at least two objects. An apparatus for video decoding according to claim 17.

19. signaling a prediction for the first of the at least two of the sub-meshes includes signaling a first prediction index and a second prediction index; the first predicted index is a single index collectively set to each of a plurality of vertices of the first one of the instances of the at least two objects; the second predicted index is set to at least one other vertex of the first one of the at least two object instances; An apparatus for video decoding according to claim 15.

20. On the computer, obtaining an input mesh corresponding to volumetric data for at least one three-dimensional (3D) visual content; partitioning the input mesh corresponding to the volumetric data into a plurality of sub-meshes, each of the sub-meshes including a respective one of the instances of the object; determining a similarity between at least two of the instances of the object; grouping the plurality of sub-meshes based on the determined similarity; decoding the volumetric data based on the grouping of the plurality of sub-meshes; A non-transitory computer-readable medium that stores a program.

Images