Vertex prediction based on decoded neighborhoods

Abstract

A method and apparatus including computer code configured to: cause one or more processors to acquire volumetric data of at least one three-dimensional (3D) visual content; derive a first layer of a mesh including a plurality of first vertices from at least one frame of the volumetric data; determine displacement vectors from vertices of the plurality of vertices of the first layer to each of a plurality of second vertices of a second layer of the mesh, wherein a total number of the plurality of second vertices is greater than a total number of the plurality of first vertices; and signal the volumetric data based on the displacement vectors.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 353,312, filed June 17, 2022, and U.S. Patent Application No. 18 / 312,265, filed May 4, 2023, which are expressly incorporated by reference in their entireties into this application.

[0002] This disclosure is directed to a set of advanced video coding techniques including mesh vertex prediction based on derived mesh triangulation for dynamic mesh compression. [Background technology]

[0003] Advances in 3D capture, modeling, and rendering are facilitating the ubiquitous presence of 3D content across several platforms and devices. Today, it is possible to film a baby's first steps on one continent while the baby's grandparents on another continent can view (and possibly interact with) that child and enjoy a fully immersive experience with that child. Yet, to achieve such realism, models are becoming ever more sophisticated, and significant amounts of data are linked to the creation and consumption of these models.

[0004] Therefore, technical solutions to such problems are desirable. Summary of the Invention [Means for solving the problem]

[0005] Methods and apparatuses are included that include a memory configured to store computer program code and one or more processors configured to access and operate as instructed by the computer program code, the computer program configured to cause the processor to execute: acquisition code configured to cause the at least one processor to acquire volumetric data of at least one three-dimensional (3D) visual content, acquisition code configured to cause the at least one processor to acquire a first layer of a mesh including a plurality of first vertices from at least one frame of the volumetric data, decision code configured to cause the at least one processor to acquire displacement vectors from a vertex of the plurality of vertices of the first layer to each of a plurality of second vertices of a second layer of the mesh, where a total number of the plurality of second vertices is greater than a total number of the plurality of first vertices, and signaling code configured to cause the at least one processor to signal the volumetric data based on the displacement vectors.

[0006] According to an exemplary embodiment, the determination code is further configured to cause the at least one processor to determine a second displacement vector from a plurality of second vertices of the second layer of the mesh and from a plurality of other vertices of the second layer of the mesh, and the signaling code is further configured to cause the at least one processor to further signal the volume data based on the second displacement vector.

[0007] According to an exemplary embodiment, a first layer of the mesh includes a polygon defined by straight lines interconnecting each of the other vertices of the plurality of first vertices, and a vertex of the plurality of first vertices is located on each of the straight lines interconnecting each of the other vertices of the plurality of first vertices.

[0008] According to an exemplary embodiment, other vertices of the plurality of first vertices are decoded vertices, vertices of the plurality of first vertices are interpolated vertices, and the polygon defines a boundary of a first layer of the mesh.

[0009] According to an exemplary embodiment, the second layer of the mesh includes a plurality of second polygons each defined by second straight lines interconnecting a plurality of second vertices of the second layer of the mesh with other vertices of the plurality of first vertices of the first layer of the mesh.

[0010] According to an exemplary embodiment, at least one of the plurality of second vertices is within the boundary of the polygon.

[0011] According to an example embodiment, each of the plurality of second vertices is within the boundary of the polygon.

[0012] According to an exemplary embodiment, the second polygons are each entirely within the boundary of the polygon.

[0013] According to an example embodiment, at least one of the plurality of second vertices is outside the boundary of the polygon.

[0014] According to an example embodiment, at least a portion of one of the second polygons is outside the boundary of the polygon.

[0015] 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]

[0016] [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 block diagram according to an embodiment. [Figure 4] FIG. 2 is a simplified block diagram according to an embodiment. [Diagram 5]1 is a schematic diagram according to an embodiment. [Figure 6] 1 is a schematic diagram according to an embodiment. [Figure 7] 1 is a schematic diagram according to an embodiment. [Figure 8] 1 is a schematic diagram according to an embodiment. [Figure 9A] 1 is a schematic diagram according to an embodiment. [Figure 9B] 1 is a schematic diagram according to an embodiment. [Figure 10] FIG. 2 is a simplified block diagram according to an embodiment. [Figure 11] FIG. 2 is a simplified block diagram according to an embodiment. [Figure 12] FIG. 2 is a simplified block diagram according to an embodiment. [Figure 13] 1 is a schematic diagram according to an embodiment. [Figure 14] 1 is a schematic diagram according to an embodiment. [Figure 15] 1 is a schematic diagram according to an embodiment. [Figure 16] 1 is a schematic diagram according to an embodiment. [Figure 17] 1 is a schematic diagram according to an embodiment. [Figure 18] 1 is a schematic diagram according to an embodiment. [Figure 19] 1 is a schematic diagram according to an embodiment. [Figure 20] 1 is a simplified flow chart according to an embodiment. [Figure 21] 1 is a simplified flow chart according to an embodiment. [Figure 22] 1 is a simplified flow chart according to an embodiment. [Figure 23] 1 is a schematic diagram according to an embodiment. [Figure 24] 1 is a schematic diagram according to an embodiment. [Diagram 25] 1 is a schematic diagram according to an embodiment. [Figure 26] 1 is a schematic diagram according to an embodiment. [Figure 27] 1 is a schematic diagram according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The proposed features discussed below may be used separately 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.

[0018] 1 illustrates 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. In the case of 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 serving applications, etc.

[0019] 1 illustrates a second pair of terminals 101, 104 provided to support bidirectional transmission of coded video, such as may occur during a video conference. For bidirectional transmission of data, each terminal 101, 104 may code video data captured at a local location for transmission to the other terminal over network 105. Each terminal 101, 104 may also receive coded video data transmitted by the other terminal, decode the coded data, and display the recovered video data on a local display device.

[0020] In FIG. 1, the terminals 101, 102, 103, 104 may be illustrated as a server, a personal computer, and a smartphone, although the principles of the present disclosure are not so limited. The embodiments of the present disclosure also apply to laptop computers, tablet computers, media players, and / or dedicated video conferencing equipment. The network 105 represents any number of networks that convey coded video data between the terminals 101, 102, 103, 104, including, for example, wired and / or wireless communication networks. The 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 the network 105 may not be important to the operation of the present disclosure unless described below in this specification.

[0021] 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 disclosed subject matter may be equally applicable to other video-enabled applications including, for example, video conferencing, digital television, storage of compressed video on digital media including CDs, DVDs, memory sticks, and the like.

[0022] 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 highlighted 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 highlighted as a lower data volume when compared to the sample stream and may be stored on a streaming server 205 for future use. One or more streaming clients 212, 207 may access the streaming server 205 to retrieve copies 208, 206 of the encoded video bitstream 204. The client 212 may include a video decoder 211 that decodes a copy 208 of an input encoded video bitstream and creates an output video sample stream 210 that can be rendered on a display 209 or other rendering device (not shown). In some streaming systems, the video bitstreams 204, 206, 208 may be encoded according to a particular video coding / compression standard. Examples of these standards are mentioned above and further described herein.

[0023] FIG. 3 may be a functional block diagram of a video decoder 300 according to one embodiment of the present invention.

[0024] The receiver 302 may receive one or more codec video sequences to be decoded by the decoder 300, in the same or other embodiments, 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 together with other data, e.g., 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 sequence 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 needed or may be small. For use over 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.

[0025] 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 information for controlling a rendering device, such as a display 312, which is potentially not an integral part of the decoder but may be coupled to the decoder. The control information for the rendering device(s) may be in the form of a Supplementary 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 be in accordance with 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 sensitivity, 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 the group. Subgroups may include Groups of Pictures (GOPs), pictures, tiles, slices, macroblocks, coding units (CUs), blocks, transform units (TUs), prediction units (PUs), etc. The entropy decoder / parser may also extract information such as transform coefficients, quantization parameter values, motion vectors, etc. from the coded video sequence.

[0026] The parser 304 may perform an entropy decoding / parsing operation on the video sequence received from the buffer 303 to produce 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.

[0027] The reconstruction of symbols 313 may involve several different units, depending on the type of coded video picture or portion 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.

[0028] Besides the functional blocks already mentioned, the decoder 300 can be conceptually subdivided into several functional units as described below. In a practical implementation operating under commercial constraints, many of these units will interact closely 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 adequate:

[0029] The first unit is a scalar / inverse transform unit 305. The scalar / inverse transform unit 305 receives quantized transform coefficients and control information from the parser 304 as symbol(s) 313, including the transform to use, block size, quantization coefficients, quantization scaling matrix, etc. The scalar / inverse transform unit 305 may output a block containing sample values ​​that may be input to an aggregator 310.

[0030] In some cases, the output samples of the scalar / inverse transform unit 305 may also 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 may be provided by the intra-picture prediction unit 307. In some cases, the intra-picture prediction unit 307 generates a block of the same size and shape as the block being reconstructed using surrounding already reconstructed information fetched from the current (partially reconstructed) picture 309. 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.

[0031] 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 to the output of the scalar / inverse transform unit by the aggregator 310 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 the motion vector and made available to the motion compensation unit in the form of symbols 313, which 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 a sub-sample accurate motion vector is in use, motion vector prediction mechanisms, etc.

[0032] 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 made 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 previous part (in decoding order) of the coded picture or coded video sequence, or may be responsive to previously reconstructed, loop filtered sample values.

[0033] The output of the loop filter unit 311 may be a sample stream that can be output to the rendering device 312 and also stored in the reference picture memory 557 for use in future inter-picture prediction.

[0034] Once a particular coded picture is fully reconstructed, it can be used as a reference picture for future prediction. Once a coded picture is fully reconstructed and the coded picture is identified as a reference picture (e.g., by parser 304), the current reference picture 309 can become part of reference picture buffer 308, and a new current picture memory can be reallocated before beginning reconstruction of a subsequent coded picture.

[0035] The video decoder 300 may perform decoding operations according to a given video compression technique documented in a standard such as ITU-T Rec. H.265. The coded video sequence may conform to the syntax specified by the video compression technique or standard used in the sense of adhering to the syntax of the video compression technique or standard as specified in the video compression technique document or standard, specifically in a profile document therein. It may also be necessary for compliance that the complexity of the coded video sequence be within a range defined by the level of the video compression technique or standard. In some cases, the level limits a maximum picture size, a maximum frame rate, a maximum reconstruction sample rate (e.g., measured in megasamples per second), a maximum reference picture size, etc. The limits set by the level may be further constrained in some cases by a Hypothetical Reference Decoder (HRD) specification and metadata for HRD buffer management signaled in the coded video sequence.

[0036] 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(s). 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.

[0037] FIG. 4 may be a functional block diagram of a video encoder 400 according to one embodiment of the present disclosure.

[0038] The encoder 400 may receive video samples from a video source 401 (not part of the encoder), which may capture the video image(s) to be coded by the encoder 400 .

[0039] 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 may 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 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 multiple individual pictures that convey 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.

[0040] 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 required by the application. Imposing an appropriate coding rate is one function of the controller 402. The controller controls and is operatively coupled to other functional units as described below. Coupling is not shown for clarity. Parameters set by the controller may include rate control related parameters (picture skip, quantizer, lambda value for rate distortion optimization techniques, ...), picture size, Groups of Pictures (GOP) layout, maximum motion vector search range, etc. Other functions of the controller 402 may be relevant to optimizing the video encoder 400 for a particular system design, and therefore may be readily identified by one skilled in the art.

[0041] 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 the reference picture(s), and a (local) decoder 406 built into the encoder 400, which reconstructs the symbols to create sample data that the (remote) decoder would 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. The decoding of the symbol stream leads to bit-exact results independent of the location of the decoder (local or remote), so the contents of the reference picture buffer 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 would "see" 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, eg, due to channel errors) is well known to those skilled in the art.

[0042] 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.

[0043] 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. The 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.

[0044] 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 manner, the coding engine 407 codes differences between pixel blocks of the input frame and pixel blocks of the reference frame(s) that may be selected as the predictive reference(s) to the input frame.

[0045] The local video decoder 406 may decode the coded video data of the frames, which may be designated as reference frames, based on the symbols created by the source coder 403. The operation of the coding engine 407 may advantageously be a lossy process. If 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 reproduce the decoding process that may be performed by the video decoder on the reference frames, and store the reconstructed reference frames in a 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 a common content as the reconstructed reference frames to be obtained by the far-end video decoder (without transmission errors).

[0046] 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 sample blocks by pixel blocks 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.

[0047] 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.

[0048] The output of all the aforementioned functional units may be subjected to 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.

[0049] The transmitter 409 may buffer the coded video sequence(s) created by the entropy coder 408 in preparation 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 ancillary data streams (source not shown).

[0050] 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 the respective picture. For example, pictures may often be assigned as one of the following frame types:

[0051] An intra picture (I-picture) may be a picture that can be coded and decoded without using any other frame 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 and their respective uses and characteristics.

[0052] A predictive picture (P picture) may be a picture that can be coded and decoded using intra- or inter-prediction, which uses at most one motion vector and reference index to predict sample values ​​for each block.

[0053] Bidirectionally predicted pictures (B-pictures) may be coded and decoded using intra- or inter-prediction that uses up to two motion vectors and reference indices to predict the sample values ​​of each block. Similarly, multi-predicted pictures may use more than two reference pictures and associated metadata for the reconstruction of a single block.

[0054] A source picture may generally be spatially subdivided into multiple sample blocks (e.g., blocks of 4x4, 8x8, 4x8, or 16x16 samples each) 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 pixel block of a B picture may be non-predictively coded via spatial prediction or via temporal prediction with reference to one or two previously coded reference pictures.

[0055] Encoder 400 may be, for example, a video coder and may perform coding operations according to a given video coding technique or standard, such as ITU-T Rec. H.265. In its operation, 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.

[0056] 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 or slices, Supplemental Enhancement Information (SEI) messages, Visual Usability Information (VUI) parameter set fragments, etc.

[0057] FIG. 5 illustrates the intra-prediction modes used in HEVC and JEM. To capture any edge direction present in natural video, the number of directional intra-modes is expanded from 33 used in HEVC to 65. The additional directional modes in HEVC plus JEM are illustrated as dotted arrows in FIG. 1(b), with the planar and DC modes remaining the same. These denser directional intra-prediction modes apply to all block sizes and to both luma and chroma intra-prediction. As shown in FIG. 5, the directional intra-prediction modes identified by the dotted arrows are associated with odd intra-prediction mode indexes and are referred to as odd intra-prediction modes. The directional intra-prediction modes identified by the solid arrows are associated with even intra-prediction mode indexes and are referred to as even intra-prediction modes. In this specification, the directional intra-prediction modes indicated by the solid or dotted arrows in FIG. 5 are also referred to as angular modes.

[0058] In JEM, a total of 67 intra prediction modes are used for luma intra prediction. To code intra modes, a Most Probable Mode (MPM) list of size 6 is constructed based on the intra modes of neighboring blocks. If the intra mode is not from the MPM list, a flag is signaled indicating whether the intra mode belongs to the selected modes. In JEM-3.0, there are 16 selected modes, which are uniformly selected every 4th angular mode. In JVET-D0114 and JVET-G0060, 16 secondary MPMs are derived to replace the uniformly selected modes.

[0059] 6 illustrates N reference layers used for the intra-directional mode. There is a block unit 611, a segment A 601, a segment B 602, a segment C 603, a segment D 604, a segment E 605, a segment F 606, a first reference layer 610, a second reference layer 609, a third reference layer 608, and a fourth reference layer 607.

[0060] In both HEVC and JEM, as well as some other standards such as H.264 / AVC, the reference samples used to predict the current block are limited to the nearest reference line (row or column). In the method of multiple reference line intra prediction, the number of candidate reference lines (rows or columns) is increased from 1 (i.e., nearest) to N for intra direction mode, where N is an integer equal to or greater than 1. Figure 2 takes a 4x4 prediction unit (PU) as an example to illustrate the concept of the multiple line intra direction prediction method. The intra direction mode can arbitrarily select one of N reference layers to generate a predictor. In other words, the predictor p(x,y) is generated from one of the reference samples S1, S2, ..., SN. A flag is signaled to indicate which reference layer is selected for the intra direction mode. If N is set as 1, the intra direction prediction method is the same as the conventional method in JEM2.0. In Figure 6, the reference lines 610, 609, 608, 607 are composed of six segments 601, 602, 603, 604, 605, 606 with an upper-left reference sample. In this specification, the reference hierarchy is also called a reference line. The coordinates of the upper-left pixel in the current block unit are (0,0), and the upper-left pixel of the first reference line is (-1,-1).

[0061] In JEM, for the luma component, the neighboring samples used for intra prediction sample generation are filtered before the generation process. The filtering is controlled by a given intra prediction mode and transform block size. If the intra prediction mode is DC or the transform block size is equal to 4×4, the neighboring samples are not filtered. If the distance between a given intra prediction mode and the vertical mode (or horizontal mode) is greater than a predefined threshold, the filtering process is enabled. A [1,2,1] filter and a bilinear filter are used for filtering the neighboring samples.

[0062] The position-dependent intra prediction combination (PDPC) method is an intra prediction method that invokes the combination of unfiltered boundary reference samples and HEVC-style intra prediction with filtered boundary reference samples. Each prediction sample pred[x][y] located at (x,y) is calculated as follows: pred[x][y]=(wL*R -1,y +wT*R x,-1 +wTL*R -1,-1 +(64-wL-wT-wTL)*pred[x][y]+32)≫6 (Formula 1) In the formula, R x,-1 , R -1,y represent the unfiltered reference samples located above and to the left of the current sample (x,y), respectively, and R -1,-1 represents the unfiltered reference sample located in the top-left corner of the current block. The weights are calculated as follows: wT=32≫((y≪1)≫shift) (Equation 2) wL=32≫((x≪1)≫shift) (Equation 3) wTL=-(wL≫4)-(wT≫4) (Formula 4) shift=(log2(width)+log2(height)+2)≫2 (Formula 5)

[0063] FIG. 7 illustrates a diagram 700 of DC mode PDPC weights (wL, wT, wTL) for the (0,0) and (1,0) positions in one 4×4 block. When PDPC is applied to DC, planar, horizontal, and vertical intra modes, no additional boundary filters such as the HEVC DC mode boundary filter and horizontal / vertical mode edge filters are required. FIG. 7 illustrates a reference sample R of PDPC applied to the upper right diagonal mode. x,-1 , R -1,y and R -1,-1 The following illustrates the definition of the prediction sample pred(x',y') located at (x',y') in the prediction block. x,-1 The coordinate x of the reference sample R is given by x=x'+y'+1. -1,ySimilarly, the y coordinate of is given by y=x'+y'+1.

[0064] 8 illustrates a Local Illumination Compensation (LIC) diagram 800, which is based on a linear model of illumination changes with a scaling factor a and an offset b, and LIC is adaptively enabled or disabled for each coding unit (CU) coded in inter mode.

[0065] When LIC is applied to a CU, a least square error method is used to derive parameters a and b by using the neighboring samples of the current CU and their corresponding reference samples. More specifically, as illustrated in Figure 8, the subsampled (2:1 subsampled) neighboring samples of the CU and the corresponding samples in the reference picture (identified by the motion information of the current CU or sub-CU) are used. The IC parameters are derived and applied separately for each prediction direction.

[0066] If the CU is coded in merge mode, the LIC flag is copied from the neighboring block in a manner similar to the motion information copy in merge mode, otherwise the LIC flag is signaled to the CU to indicate whether LIC is applied or not.

[0067] 9A illustrates intra-prediction modes 900 used in HEVC. In HEVC, there are a total of 35 intra-prediction modes, of which mode 10 is a horizontal mode, mode 26 is a vertical mode, and modes 2, 18, and 34 are diagonal modes. The intra-prediction modes are signaled by three most probable modes (MPMs) and 32 remaining modes.

[0068] 9B illustrates that in a VVC embodiment, there are a total of 87 intra-prediction modes, where mode 18 is a horizontal mode, mode 50 is a vertical mode, and modes 2, 34, and 66 are diagonal modes. Modes -1 to -10 and modes 67 to 76 are referred to as wide-angle intra-prediction (WAIP) modes.

[0069] A prediction sample pred(x,y) located at position (x,y) is predicted using a linear combination of reference samples according to the intra prediction mode (DC, planar, angular) and the PDPC formula as follows: pred(x,y)=(wL×R-1,y+wT×Rx,-1-wTL×R-1,-1+(64-wL-wT+wTL)×pred(x,y)+32)>>6 (Formula 6) where Rx,-1, R-1,y represent the reference samples located above and to the left of the current sample (x,y), respectively, and R-1,-1 represents the reference sample located in the top left corner of the current block.

[0070] For DC mode, the weights are calculated for a block with dimensions width and height as follows: wT=32>>((y<<1)>>nScale),wL=32>>((x<<1)>>nScale),wTL=(wL>>4)+(wT>>4) (Equation 7) nScale=(log2(width)-2+log2(height)-2+2)>>2, where wT represents the weighting factor of the reference sample located on the top reference line with the same horizontal coordinate, wL represents the weighting factor of the reference sample located on the left reference line with the same vertical coordinate, and wTL represents the weighting factor of the top-left reference sample of the current block, and nScale specifies how fast the weighting factor decreases along the axis (wL decreases from left to right, or wT decreases from top to bottom), i.e., the weighting factor decrease rate, which is the same along the x-axis (from left to right) and y-axis (from top to bottom) in the current design. And 32 represents the initial weighting factor of the neighboring samples, and the initial weighting factor is also the top (left or top-left) weighting assigned to the top-left sample in the current CB, and the weighting factor of the neighboring samples in the PDPC process should be less than or equal to this initial weighting factor.

[0071] In planar mode, wTL = 0, in horizontal mode, wTL = wT, and in vertical mode, wTL = wL. The PDPC weights can be calculated with additions and shifts only. The value of pred(x,y) can be calculated in a single step using Equation 1.

[0072] FIG. 10 illustrates a simplified block-style workflow diagram 1000 of example viewport-dependent processing in Omnidirectional Media Application Format (OMAF) that may enable 360-degree virtual reality (VR360) streaming described in OMAF.

[0073] In acquisition block 1001, video data A is acquired, such as multiple image and audio data of the same time instance, if the image data can represent a scene in VR360. In processing block 1003, image B of the same time instance is acquired. iare processed by one or more of stitching, mapping onto a projected picture for one or more virtual reality (VR) angles or other angles / viewpoints, and packed by region. Additionally, metadata indicating any of such processed and other information may be created to aid in the distribution and rendering processes.

[0074] For data D, in the image encoding block 1005, the projected picture is i In the viewport independent streaming, the video pictures are encoded into a media file and then organized into a media file. In the video encoding block 1004, the video pictures are encoded into a data E, 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

[0075] Data E a , E v , and E i , the coded bitstream F iand / or the entirety of F may be stored in a (content delivery network (CDN) / cloud) server and may be transmitted in its entirety, typically in a distribution block 1007 or otherwise, to the OMAF player 1020, from which it may be fully decoded by a decoder in a display block 1016 such that at least one area of ​​the decoded picture corresponding to the current viewport in terms of various metadata, file playback, and orientation / viewport metadata, such as the angle the user may be looking through the VR imaging device in terms of the viewport specifications of that device, is rendered to the user. A distinctive feature of VR360 is that only the viewport may be displayed at any particular time, and such a feature may be used to improve the performance of an omnidirectional video system by selective distribution according to the user's viewport (or any other criteria, such as recommended viewport-timed metadata). For example, viewport-dependent distribution may be enabled by tile-based video coding according to an exemplary embodiment.

[0076] Similar to the encoding blocks described 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 produce audio data E' in audio decode block 1010. i The video decode block 1013 decodes the video data E' v In the image decoding block 1014, image data E' i and decodes the data A' in VR360 format according to various metadata such as orientation / viewport metadata in a display block 1016. i The speaker / headphone block 1012 outputs the audio data A' s In order to output the data B' in the audio rendering block 1011, aand image rendering of the data D' in audio rendering and image rendering block 1015. It should be understood that various metadata may affect 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.

[0077] 11 illustrates a simplified block-style content flow process diagram 1100 of (coded) point cloud data with viewpoint- 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 features described may be used separately or combined in any order, and that elements such as encoding and decoding, among others, illustrated, may be performed by processing circuitry (e.g., one or more processors or one or more integrated circuits), and that the one or more processors may execute a program stored on a non-transitory computer-readable medium according to an exemplary embodiment.

[0078] Diagram 1100 illustrates an example embodiment for streaming coded point cloud data with V-PCC.

[0079] In volume 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 synthesized by a computer as volume data, which may have any format and 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 volume data may be converted area data-wise into a point of a point cloud by pulling one or more of the values ​​described below from the volume data and any associated data into a desired point cloud format according to an exemplary embodiment. According to an exemplary embodiment, the volume data may be a 3D dataset of 2D images, such as slices from which 2D projections 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, such as with respect to temporal redundancy; for example, point cloud data in x, y, z format may represent color values ​​(e.g., RGB, etc.), brightness, intensity, etc. at each of a plurality of points of the cloud data and may also be used in conjunction with progressive decoding, polygon meshing, direct rendering, and octree 3D representation of 2D quadtree data.

[0080] In a projection onto image block 1103, the acquired point cloud data may be projected onto 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 reconstruction of the point cloud data using, for example, Painter's algorithm, ray casting algorithms, (3D) binary space partitioning algorithms, among others.

[0081] Meanwhile, in the scene generator block 1109, the scene generator may generate some metadata to be used for rendering and displaying 6 degrees of freedom (DoF) media, for example according to the director's intent or user's preferences. Such 6DoF media may include 360VR-like 3D viewing 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 or at least in relation to the virtual experience according to the point cloud coded data. 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 indicated in FIG. 11 and related description.

[0082] After a video encoding block 1104 and an image encoding block 1105 similar to the video and image encoding described above (it will also be appreciated that audio encoding may also be provided as described above), a file / segment encapsulation block 1106 processes the coded point cloud data so that it is arranged into a media file for file playback or a sequence of default segments and media segments for streaming in a particular media container file format, such as one or more video container formats, and in particular may be used with respect to DASH, described below, such description representing an exemplary embodiment. The file container may also include scene description metadata, such as from a scene generator block 1109, in the file or segment.

[0083] According to an exemplary embodiment, the files are encapsulated according to scene description metadata to each include at least one viewpoint position at one or more times in the 6DoF media and at least one or more angular views at the one or more viewpoint positions, such that such files may be transmitted on demand 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, such as a portion of the 6DoF media indicating a single viewpoint and angle at that viewpoint at one or more times, although these are merely exemplary embodiments and may be modified according to various conditions, such as network, user, creator capabilities and input.

[0084] According to an example embodiment, the point cloud data is divided into multiple 2D / 3D regions, which 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 track within a file and / or segment 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 viewpoint position / angle dependent processing.

[0085] According to an exemplary embodiment, metadata such as included in a file and / or segment encapsulated with respect to a file / segment encapsulation block useful for viewpoint position / angle dependent processing 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 viewpoint position / angle list; a selected viewpoint position / angle list corresponding to the 3D volume partition; an index of the 2D / 3D partition corresponding to the selected viewpoint position / angle list; information of the quality (rank) of each 2D / 3D partition; and rendering information of each 2D / 3D partition according to, for example, each viewpoint position / angle. Soliciting 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 particular portions of the 6DoF media for which such metadata is desired, such that the V-PCC player may deliver a higher quality image of a valued portion of the media than other portions, rather than delivering unused portions of the 6DoF media.

[0086] The file or one or more segments of the file may be delivered from the File / Segment Encapsulation block 1106 using a delivery mechanism (e.g., by Dynamic Adaptive Streaming over HTTP (DASH)) to the V-PCC Player 1125 as well as directly to a cloud server, such as in the Cloud Server block 1107, where the cloud server can extract one or more tracks and / or one or more specific 2D / 3D partitions from the file and merge multiple coded point cloud data into one data.

[0087] If the current viewpoint position and angle(s) are defined on the 6DoF coordinate system at the client system according to data such as position / viewing angle tracking block 1108, the cloud server may extract the appropriate partition(s) from the store file(s) and merge them (if necessary) depending on metadata, for example from a client system having a V-PCC player 1125, and the viewpoint position / angle metadata may be delivered from file / segment encapsulation block 1106 so that the extracted data can be delivered to the client as a file or segment, or may alternatively be processed in other manner in cloud server block 1107 from a file or segment already on the cloud server.

[0088] With regard to 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 then in video decode and image decode block, the coded point cloud data is decoded and in point cloud reconstruction block 1112, reconstructed into point cloud data which can be displayed in display block 1114 and / or, with regard to scene description data by scene generator block 1109, may be initially configured according to one or more various scene descriptions in scene composition block 1113.

[0089] 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 ability to assemble compressed domains of coded 2D / 3D partitions into a single coherent coded video bitstream, and the bitstream extraction capabilities of the coded 2D / 3D of a coded picture into a coherent coded bitstream, and such V-PCC system support is further improved by the inclusion of a container formation for the VVC bitstream to support a mechanism for housing metadata carrying one or more of the above-mentioned metadata.

[0090] In that regard, according to an exemplary embodiment described further below, the term "mesh" refers to a configuration of one or more polygons that describe the surface of a volumetric object. Each polygon is defined by its vertices in 3D space and information about how the vertices are connected, called connectivity information. Optionally, vertex attributes such as color, normals, etc. may also be associated with the mesh vertices. Attributes may also be associated with the surface of the mesh by utilizing mapping information that parameterizes the mesh with a 2D attribute map. Such mapping may be defined by a set of parametric coordinates, called UV coordinates or texture coordinates, associated with the mesh vertices. The 2D attribute map is used to store high-resolution attribute information such as texture, normals, displacements, etc. Such information may also be used for various purposes such as texture mapping and shading, according to an exemplary embodiment.

[0091] 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 constant connectivity and time-varying geometry and vertex attributes. However, these standards do not take into account time-varying attribute maps and connectivity information. DCC (Digital Content Creation) tools usually generate such dynamic meshes. Correspondingly, it is difficult for volume acquisition techniques to generate constant 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 for directly processing 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.

[0092] FIG. 12 represents one dynamic mesh compression example framework 1200 for 2D atlas sampling based methods, etc. Each frame of an input mesh 1201 can be pre-processed by a series of operations, e.g., tracking, remeshing, parameterization, voxelization. Note 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, e.g., indicating 0 for encoder only and 1 for others. Then, a mesh with a 2D UV atlas 1202 can be obtained, and each vertex of the mesh has one or more associated UV coordinates on the 2D atlas. Then, the mesh can be converted into multiple maps, including geometry maps and attribute maps, by sampling on the 2D atlas. These 2D maps can then be coded by video / image codecs, 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 the boundary vertices, can be predicted, quantized and entropy coded in the bitstream. The quantization step size can be configured at the encoder side for a tradeoff between quality and bitrate.

[0093] 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 illustrated in the volume data example 1300 of FIG. 13, the UV parameterization process 1302 of mapping 3D mesh segments onto a 2D chart, such as the 2D UV atlas 1202 block described above, maps one or more mesh segments 1301 onto a 2D chart 1303 in the 2D UV atlas 1304. Each vertex (v n ) will be assigned 2D UV coordinates in the 2D UV atlas. n Note that vertices v1, v2, and v3 form a connected component as their 3D corresponding vertices. The geometry, attributes, and connectivity information of each vertex can be inherited from their 3D counterparts as well. For example, if vertex v4 is connected to vertex v 0、 v 5、 Information about the direct connection of v1, v3 may be indicated, and similarly, information for each of the other vertices may be supported as well. Furthermore, such a 2D texture mesh, according to an exemplary embodiment, further indicates information such as color information, patch by patch, such as patches of v2, v5, v3, at least for each triangle shown in example 1600 of FIG. 16 .

[0094] For example, see example 1400 in FIG. 14, where, in addition to the features of example 1300 in FIG. 13, a 3D mesh segment 1301 can also be mapped to multiple separate 2D charts 1401, 1402. In this case, a vertex in 3D can also correspond to multiple vertices in the 2D UV atlas. As shown in FIG. 14, the same 3D mesh segment is mapped to multiple 2D charts in the 2D UV atlas, instead of a single chart as in FIG. 13. For example, 3D vertices v1, v4 have two 2D correspondences v1, v4, respectively. 1’and v4, v 4’ Thus, a typical 2D UV atlas for a 3D mesh may consist of multiple charts as shown in Figure 14, where each chart may contain multiple vertices (usually three or more) associated with their 3D geometry, attributes, and connectivity information.

[0095] FIG. 15 shows an example 1500 illustrating the derived triangulation in a chart with boundary vertices B0, B1, B2, B3, B4, B5, B6, B7. Given such information, any triangulation method 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 1500, there are repeating triangles of various regular shapes and triangles of various irregular shapes, which are generally closest to the boundary vertices and have their own unique dimensions that may or may not be shared with any 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.

[0096] Turning to the patches discussed above, the example 1500 may represent one such patch, such as the patch formed from vertices v3, v2, and v5 shown in either FIG. 14 or FIG.

[0097] Boundary vertices B0, B1, B2, B3, B4, B5, B6, B7 are defined in 2D UV space. As shown in Figure 15, a filled vertex is a boundary vertex because it is on the boundary edge of a connected component (patch / chart). A boundary edge can be determined by checking if the edge appears in only one triangle. The following information of a boundary vertex is important and needs to be signaled in the bitstream according to an exemplary embodiment: Geometry information, e.g., 3D XYZ coordinates even if currently in 2D UV parameter format, and 2D UV coordinates.

[0098] For the case where a bounding vertex in 3D corresponds to multiple vertices in the 2D UV atlas, the mapping from 3D XUZ to 2D UV can be one-to-many, as shown in Figure 14. Therefore, a UV to XYZ (or called UV2XYZ) index can be signaled to indicate the mapping function. UV2XYZ can be a 1D array of indexes that maps each 2D UV vertex to a 3D XYZ vertex.

[0099] According to an example 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 because the vertices are subsampled from the original mesh. There are various ways to signal connectivity information between vertices, and therefore such a subset is referred to as a base mesh or base vertices.

[0100] However, other vertices can be predicted by applying interpolation between two or more already decoded mesh vertices. A predictor vertex has its geometric position along the edges of two connected existing vertices, so the geometric information of the predictor can be calculated based on the decoded vertices in the neighborhood. In some cases, a displacement vector or a prediction error from the vertex to be coded to the vertex predictor should be further coded. See, for example, example 1800 of FIG. 18, which shows an example of such edge-based vertex prediction, more specifically, 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., solid triangles 1801 on the left of FIG. 18), the interpolation between these base vertices can be performed along the connecting edges. For example, the midpoint of each edge can be generated as a predictor. The geometric position of these interpolated points is therefore the (weighted) average of the two nearby decoded vertices (dashed points 1802 on the left of FIG. 18). Having more than one midpoint between two already decoded vertices can also be done in a similar way. Thus, the actual vertex to be coded can be reconstructed by adding a displacement vector to the predictor (Fig. 7 center). After decoding these additional vertices, the connection between the newly decoded vertex and the existing base vertex is still maintained. In addition, more connections between the newly decoded vertices can be established. Along with the base vertex, more intermediate vertex predictors can be generated along new edges (Fig. 7 right) by connecting these newly decoded vertices 1803 and the base vertex to each other. Thus, there are more actual vertices to be decoded with associated displacement vectors. Here, the "displacement vector" represents the distance and direction from the vertex.

[0101] According to an example embodiment, mesh vertices of mesh frame 1902 can also be predicted from the decoded vertices of the previously coded mesh frame 1901. This prediction mechanism is called inter prediction. An example of mesh geometry inter prediction is shown in example 1900 of FIG. 19 showing vertex geometry prediction using inter prediction (vertices of the previous mesh frame become predictors of vertices of the 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.

[0102] 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 can be applied individually or in any form of combination.

[0103] Consider, for example, vertex grouping for the example flowchart 2000 of prediction modes in FIG. 20. In S201, vertices in a mesh may be obtained, and in S202, they can be divided into different groups for prediction purposes, see, for example, FIG. 15. In one example, the division is done using patch / chart division in S204 as previously discussed. In another example, the division is done 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 can be assigned at different levels by determining the number of respective vertices involved per group. For example, every 64, 32, or 16 vertices by scan order in a patch / chart may be assigned the same prediction mode according to an example 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 2000, if a mesh frame or mesh slice is determined to be an intra type in S207, such as by checking whether a flag for the mesh frame or mesh slice indicates an intra type, then all vertex groups within the mesh frame or mesh slice shall use intra prediction mode, otherwise, in S208, either intra prediction mode or inter prediction mode may be selected per group for all vertices therein.

[0104] 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. The subpartition may sometimes 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 may be determined and signaled by flags, etc. The above prediction features may be performed in S210, and the results of the above prediction and signaling may occur in S211.

[0105] According to an exemplary embodiment, for each vertex in a vertex group in the exemplary flowchart 2000 and the flowchart 2100 described below, after prediction, the residual becomes a 3D displacement vector that indicates the shift from the current vertex to its predictor. The residual of the vertex group 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 a group of displacement vectors, the following methods can be implemented. For example, in one method, to properly signal the case where a group of displacement vectors, some displacement vectors, or its components have only zero values. In another embodiment, a flag can be 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 can be 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 may be 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 may be skipped. Further, in other embodiments, there may be a signaling if a group of displacement vectors or a component of a group of displacement vectors requires a transform, and if not, the transform may be skipped and quantization / entropy coding may 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 may 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 may also be combined and performed in parallel, each on a different patch.

[0106] FIG. 21 shows an example flowchart 2100, in which a mesh frame can be coded and obtained as a whole data unit in S221, meaning that all vertices or attributes of the mesh frame may have correlation between them. Alternatively, depending on the decision in S222, the mesh frame can also be divided into smaller independent subpartitions in S223, in a concept similar to slices or tiles of a 2D video or image. The coded mesh frame or the coded mesh subpartition can be assigned a prediction type in 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 in S225. Meanwhile, the inter-prediction type allows prediction from a previously coded mesh frame in addition to intra-mesh frame prediction in S225. Furthermore, the inter-prediction type can 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 can be used to generate a predictor. A weighted average of two predictors can be an example. If the mesh frame is coded as a whole, the frame can be considered as an intra- or inter-coded mesh frame. For inter-mesh frames, the P or B type can be further identified via signaling. Alternatively, if the mesh frame is coded with further division within the frame, the prediction type assignment of each of the sub-partitions is made in S224. Each of the above information may be determined and signaled by flags, etc., and similar to S210 and S211 of FIG. 20, the features of said prediction may be made in S226, and the results of said prediction and signaling may occur in S227.

[0107] As such, dynamic mesh sequences may require large amounts of data as they may consist of a significant amount of information that changes over time, and efficient compression techniques are required to store and transmit such content, and the above-mentioned features of Figures 20 and 21 represent such improved efficiency by enabling at least improved mesh vertex 3D position prediction by using previously decoded vertices either within the same mesh frame (intra prediction) or from a previously coded mesh frame (inter prediction).

[0108] 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, predictors of vertices in the third layer 2303T+1 are 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 2300 of FIG. 23, which illustrates reconstruction-based vertex prediction, i.e., progressive vertex prediction using edge-based interpolation, where predictors are 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 at its boundary and the interpolated vertices along the lines between the lines of these decoded vertices. As the progressive coding proceeds from the first layer 2301 to the second layer 2302, additional polygons 2341 may be formed by displacement vectors from the interpolated vertices of the first layer to additional vertices of the second layer 2302, such 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, 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 functioned in proceeding from the first layer 2301 to the second layer 2303, i.e., multiple additional polygons may be formed. As a note, unlike Figure 23, example 2600 illustrates that when moving from a first layer 2601 to a second layer 2603 and then to a third layer 2603, each of the additionally formed polygons may be entirely within the polygon formed by the extent of the first layer 2601; see example 2600 in Figure 26 which illustrates such progressive coding.

[0109] For such an example 2300, since the interpolated vertices of the current layer are predicted values, such values need to be reconstructed before being used to generate predictors for the vertices of the next layer. Refer to the exemplary flowchart 2200 of FIG. 22. This is done by coding the base mesh at S231, performing vertex prediction as such at S232, and then adding the decoded displacement vectors of the current layer to the predictors of the vertices such as layer 2302 at S233. Then, the reconstructed vertices of this layer 2303 can be used to generate and signal the predictor vertices of the next layer 2303 at S235, along with all the decoded vertices of the previous (one or more) layers, such as checking the additional vertex values of such layers at S234. This process can also be summarized as follows. Let P[t](Vi) represent the predictor of vertex Vi on layer t, R[t](Vi) represent the reconstructed vertex Vi on layer t, D[t](Vi) represent the displacement vector of vertex Vi of layer t, and f(*) represent a predictor generator that can be, in particular, the average of two existing vertices. In that case, according to an exemplary embodiment, for each layer t, the following exists. 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 (8)

[0110] Then, for all the vertices of one mesh frame, they are divided into layer 0 (base mesh), layer 1, layer 2, …, etc. In that case, the reconstruction of the vertices on one layer depends on the reconstruction of the vertices on the previous (one or more) layers. Above, each of P, R, and D represents a 3D vector in the context of a 3D mesh representation. D is the decoded displacement vector, and quantization may or may not be applied to this vector.

[0111] 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, the selection of reconstruction-based vertex prediction or predictor-based vertex prediction can be signaled, or the layer (and subsequent layers) that does not use reconstruction-based vertex prediction can be signaled.

[0112] For displacement vectors generated by vertices whose vertex predictors are reconstructed, quantization can be applied to those displacement vectors without further transformation, such as wavelet transform, etc. For displacement vectors whose vertex predictors are generated by other predictor vertices, a transformation may be required and quantization can be applied to the transform coefficients of those displacement vectors.

[0113] As such, dynamic mesh sequences may require large amounts 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, one important step is compressing the displacement vectors, which occupy a major part in the coded bitstream and are the focus of this disclosure, and the features of, for example, FIG. 22, alleviate such problems by providing such compression.

[0114] Furthermore, as with the other examples described above, even in those embodiments, dynamic mesh sequences may still require a large amount of data since they may consist of a significant amount of information that changes over time, and therefore 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 may be achieved by inferring connectivity information from sampled vertices and boundary vertices at the decoder side. This is a key part of the decoding process and is the focus of further examples described below.

[0115] According to an example embodiment, the connectivity information of the base mesh can be inferred (derived) from the decoded boundary vertices and sampled vertices for each chart on both the encoder and decoder sides.

[0116] Similar to that described above, any triangulation method can be applied to create connectivity between vertices (including boundary vertices and sampled vertices). For charts without sampling of interior vertices, such as the interior vertices shown in example 1500 of FIG. 15 and example 2500 of FIG. 25 described further below, a similar method of creating connectivity still applies, but according to an example embodiment, the use of different triangulation methods for boundary vertices and sampled vertices may be signaled.

[0117] 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 greater than or equal to three (examples of occupied or unoccupied points are highlighted in FIG. 25, which shows an example occupancy map 2500, where each circle represents an integer pixel), and the triangular connectivity between the four points can be inferred by a certain rule. For example, as illustrated in example 2400 of FIG. 24, in the case of the illustrated examples (2), (3), (4), (4), where three of the four points are determined to be occupied, the points can be directly interconnected to form a triangle as in those examples, whereas, if all four points are determined to be occupied, the points are used to form two triangles as shown in example (1) of FIG. 24. It should be noted that different rules can be applied to different numbers of neighboring points. This process can be performed across many points, as further illustrated in FIG. 25. In this embodiment, the reconstructed mesh is a triangular mesh such as that of FIG. 24, and also a regular triangular mesh in at least the interior portion of FIG. 25, which may not be determined to be signaled according to such regularity, but may instead be coded and decoded as surrounding irregular triangles that should be signaled separately, by inference rather than by separate signaling.

[0118] Also, in an attempt to further reduce complexity and data processing, such a regular interior triangular quad mesh as shown in FIG. 25 could be inferred as such a quad mesh of example (1) of FIG. 24, thereby even reducing the amount of complexity from inferring interior regular triangles to inferring a reduced number of interior regular quad meshes instead.

[0119] According to an example embodiment, a quadrilateral mesh may be reconstructed when all four neighboring points are determined to be occupied, as in example (1) of FIG.

[0120] Inferring from the above description, it is illustrated that the reconstructed mesh in example 2500, as shown in FIG. 25, may be of hybrid type, i.e., some regions within the mesh frame generate triangular meshes and other regions generate quadrilateral meshes, some of the triangular meshes being regular compared to other triangular meshes therein, and some, such as boundary triangular meshes, may be irregular, although not necessarily all such meshes are on the boundary.

[0121] According to an example embodiment, such connectivity type can be signaled in a high level syntax such as a sequence header or slice header.

[0122] As mentioned above, connectivity information can also be reconstructed by explicit signaling, as in the case for irregularly shaped triangular meshes. That is, if it is determined that a polygon cannot be reconstructed 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 2500 of FIG. 25, the connectivity information of a triangle is to be signaled to be reconstructed by both implicit rules, as according to the regular example 2400 of FIG. 24, which can be inferred, and explicit signaling, at least for irregularly shaped polygons, shown on the mesh boundary in FIG. 25.

[0123] According to an embodiment, it is decided that only connectivity information between boundary vertices and sampled locations is signaled; connectivity information between the sampled locations themselves is inferred.

[0124] Also, in any of the embodiments, connectivity information can be signaled predictively, such that only the difference between the estimated connectivity (as a prediction) from one mesh to another can be signaled in the bitstream.

[0125] 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 sequence header, slice header, etc., 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.

[0126] 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, while the reconstructed mesh may be a polygon mesh (e.g., a quad mesh).

[0127] 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 side. See, for example, how the bottom vertices of example 2500 are all occupied, and thus the coding may utilize such information by inferring later, thus determining that such vertices are occupied as bases, thereby 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 side. Also, according to an exemplary embodiment, the predicted vertex interpolation for additional mesh vertices may be based on the derived edges of the base mesh.

[0128] According to an example 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 the sequence level, the frame level, etc.

[0129] 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.

[0130] 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, connectivity on and vertex interpolation involving boundary edges may be performed separately from interior vertices and edges.

[0131] Thus, by the exemplary embodiments described herein, the technical problems described 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 therefore the exemplary embodiments described herein represent at least an efficient compression technique for storing and transmitting such content.

[0132] The techniques described above can be implemented as computer software physically stored on one or more computer readable media using computer readable instructions, or by one or more specifically configured hardware processors. For example, Figure 27 illustrates a computer system 2600 suitable for implementing certain embodiments of the disclosed subject matter.

[0133] 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 directly by a computer central processing unit (CPU), graphics processing unit (GPU), etc., or via interpretation, microcode execution, etc.

[0134] The instructions may be executed on various types of computers or computer components including, for example, personal computers, tablet computers, servers, smartphones, gaming consoles, Internet of Things devices, and the like.

[0135] 27 for computer system 2700 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. Neither should the arrangement of components be interpreted as having a dependency or requirement regarding any one or combination of components illustrated in the exemplary embodiment of computer system 2700.

[0136] The computer system 2700 may include certain human interface input devices. Such human interface input devices may be responsive to input by one or more human users via, for example, tactile input (e.g., keystrokes, swipes, data glove movements), audio input (e.g., voice, clapping), visual input (e.g., gestures), olfactory input (not shown). The human interface devices may also be used to capture certain media not necessarily directly associated with conscious human input, such as audio (e.g., voice, music, ambient sounds), images (e.g., scanned images, photographic images obtained from still image cameras), video (two-dimensional video, three-dimensional video including stereoscopic video, etc.).

[0137] The input human interface devices may include one or more of a keyboard 2701, a mouse 2702, a trackpad 2703, a touch screen 2710, a joystick 2705, a microphone 2706, a scanner 2708, a camera 2707 (only one of each is shown).

[0138] The computer system 2700 may also include certain human interface output devices. Such human interface output devices may stimulate one or more of the senses of a human user, for example, through haptic output, sound, light, and smell / taste. Such human interface output devices may include haptic output devices (e.g., haptic feedback via touch screen 2710 or joystick 2705, although there may also be haptic feedback devices that do not function as input devices), audio output devices (e.g., speakers 2709, headphones (not shown)), visual output devices (e.g., screens 2710 including CRT screens, LCD screens, plasma screens, OLED screens, each with or without touch screen input functionality, 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 stereoscopic output, virtual reality glasses (not shown), holographic displays, and smoke tanks (not shown)), and printers (not shown).

[0139] The computer system 2700 may also include human accessible storage devices and their associated media, such as optical media including a CD / DVD ROM / RW 2720 having media such as CD / DVD 2711, a thumb drive 2722, a removable hard drive or solid state drive 2723, legacy magnetic media such as tape or floppy disks (not shown), dedicated ROM / ASIC / PLD based devices such as security dongles (not shown), etc.

[0140] Those skilled in the art will 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.

[0141] The computer system 2700 may also include an interface 2799 to one or more communications networks 2798. The networks 2798 may be, for example, wireless, wired, optical. The networks 2798 may further be local, wide area, metropolitan, vehicular and industrial, real-time, delay tolerant, etc. Examples of networks 2798 include local area networks such as Ethernet, WLAN, etc., cellular networks including GSM, 3G, 4G, 5G, LTE, etc., television wired or wireless wide area digital networks including cable television, satellite television, and terrestrial broadcast television, vehicular and industrial including CANBus, etc. Specific networks 2798 generally require an external network interface adapter attached to a specific general-purpose data port or peripheral bus (2750 and 2751) (e.g., a USB port of the computer system 2700, etc.), while other networks are generally built into the core of the computer system 2700 by connection 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 2798, the computer system 2700 can communicate with other entities. Such communications can be unidirectional receive only (e.g., broadcast television), unidirectional transmit only (e.g., CANbus to certain CANbus devices), or bidirectional to other computer systems using, for example, local or wide area digital networks. Specific protocols and protocol stacks can be used with each of these networks and network interfaces, as described above.

[0142] The aforementioned human interface devices, human accessible storage devices, and network interfaces can be connected to core 2740 of computer system 2700.

[0143] The core 2740 may include one or more central processing units (CPUs) 2741, graphics processing units (GPUs) 2742, graphics adapters 2717, dedicated programmable processing units in the form of field programmable gate areas (FPGAs) 2743, hardware accelerators for specific tasks 2744, etc. These devices may be connected via a system bus 2748 along with read only memory (ROM) 2745, random access memory 2746, internal mass storage such as an internal non-user accessible hard drive, SSD, etc. 2747. In some computer systems, the system bus 2748 may be accessible in the form of one or more physical plugs to allow expansion with additional CPUs, GPUs, etc. Peripheral devices may be connected directly to the core's system bus 2748 or via a peripheral bus 2749. Architectures for peripheral buses include PCI, USB, etc.

[0144] The CPU 2741, GPU 2742, FPGA 2743, and accelerator 2744 can execute certain instructions that may combine to constitute the aforementioned computer code. That computer code may be stored in ROM 2745 or RAM 2746. Persistent data may be stored, for example, in internal mass storage 2747, while temporary data may also be stored in RAM 2746. Rapid storage and retrieval in any of the memory devices may be made possible by the use of cache memories that may be closely associated with one or more of the CPU 2741, GPU 2742, mass storage 2747, ROM 2745, RAM 2746, etc.

[0145] 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.

[0146] By way of example and not limitation, computer system 2700 having the architecture, and specifically core 2740, may provide functionality as a result of processor(s) (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 described above, as well as media associated with specific storage of core 2740 of a non-transitory nature, such as core internal mass storage 2747 and ROM 2745. Software implementing various embodiments of the present disclosure may be stored in such devices and executed by core 2740. Computer-readable media may include one or more memory devices or chips, depending on the particular needs. The software may cause core 2740, and specifically the processors therein (including CPU, GPU, FPGA, etc.) to perform particular processes or particular portions of particular processes described herein, including defining data structures stored in RAM 2746 and modifying such data structures according to the software-defined processes. Additionally or alternatively, the computer system may provide functionality as a result of logic hardwired or otherwise embodied in circuitry (e.g., accelerator 2744), which may operate in place of or in conjunction with software to perform particular processes or particular portions of particular processes described herein. References to software may encompass logic, where appropriate, and vice versa. References to computer-readable media may encompass circuitry (such as integrated circuits (ICs)) 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.

[0147] While this disclosure describes several exemplary embodiments, there are alterations, permutations, 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 thus within its spirit and scope. [Explanation of symbols]

[0148] 100 communication system, 101 terminal, 102 terminal, 103 terminal, 104 terminal, 105 network, 201 video source, 202 encoder, 203 capture subsystem, 204 encoded video bitstream, 205 streaming server, 206 copy of encoded video bitstream, 207 streaming client, 208 copy of encoded video bitstream, 209 display, 210 output video sample stream, 211 video decoder, 212 streaming client, 213 uncompressed video sample stream, 300 decoder, 301 channel, 302 receiver, 303 buffer memory, 304 parser, 305 scaler / inverse transform unit, 306 motion compensation prediction unit, 307 intra prediction unit, 308 reference picture buffer, 309 current picture, 310 aggregator, 311 loop filter, 312 display, 313 Symbol, 400 Encoder, 401 Source, 402 Controller, 403 Source Coder, 404 Predictor, 405 Reference Picture Memory, 406 Decoder, 407 Coding Engine, 408 Entropy Coder, 409 Transmitter, 410 Coded Video Sequence, 411 Channel, 601 Segment A, 602 Segment B, 603 Segment C, 604 Segment D, 605 Segment E, 606 Segment F, 607 Fourth Reference Layer, 608 Third Reference Layer, 609 Second Reference Layer, 610 First Reference Layer, 611 Block Unit, 700 Diagram, 800 Local Illumination Compensation (LIC) Diagram, 900 Intra Prediction Mode, 1000 Workflow Diagram, 1001 Acquisition Block, 1002 Audio Encode Block, 1003 Processing Block, 1004 Video Encode Block, 1005 image encoding block, 1007 distribution block, 1008 head / eye tracking block, 1010 audio decoding block, 1011 audio rendering block, 1012 speaker / headphone block, 1013 video decoding block, 1014 image decoding block, 1015 image rendering block, 1016Display block, 1020 OMAF player, 1100 Content flow process diagram, 1101 Volume data acquisition block, 1102 Point cloud block, 1103 Image block, 1104 Video encoding block, 1105 Image encoding block, 1106 File / segment encapsulation block, 1107 Cloud server block, 1108 Position / viewing angle tracking block, 1109 Scene generator block, 1112 Point cloud reconstruction block, 1113 Scene composition block, 1114 Display block, 1125 V-PCC player, 1200 One dynamic mesh compression framework, 1201 Input mesh, 1202 2D UV atlas, 1203 Decoder, 1204 Reconstructed mesh, 1300 Volume data example, 1301 3D mesh segment, 1302 UV parameterization process, 1303 2D chart, 1304 2D UV atlas, 1400 example, 1401 2D chart, 1402 2D chart, 1500 example, 1600 example, 1700 example, 1800 example, 1801 solid triangle, 1802 dashed point, 1803 newly decoded vertices, 1900 example, 1901 previously coded mesh frame, 1902 mesh frame, 2000 example flowchart, 2100 example flowchart, 2200 example flowchart, 2300 example, 2301 first layer, 2302 second layer, 2303 third layer, 2340 first polygon, 2341 additional polygon, 2400 example, 2500 example, 2600 example, 2601 first layer, 2602 second layer, 2603 third layer, 2700 computer system, 2701 keyboard, 2702 mouse, 2703 track pad, 2705 joystick, 2706 microphone, 2707 camera, 2708 scanner, 2709 speaker, 2710 touch screen, 2720 CD / DVD ROM / RW, 2711 CD / DVD or other media, 2717 graphics adapter, 2722 thumb drive, 2723 removable hard drive or solid state drive, 2740 core, 2741 central processing unit (CPU), 2742 graphics processing unit (GPU), 2743field programmable gate area (FPGA), 2744 hardware accelerator, 2745 read only memory (ROM), 2746 random access memory, 2747 internal mass storage, 2748 system bus, 2749 peripheral bus, 2750 general purpose data port or peripheral bus, 2751 general purpose data port or peripheral bus, 2798 communications network, 2799 interface to communications network

Claims

1. 1. A method for video coding, the method being performed by at least one processor, comprising: acquiring volume data of at least one three-dimensional (3D) visual content; deriving a first layer of a mesh comprising a first plurality of vertices from at least one frame of the volumetric data; determining a displacement vector from a vertex of the plurality of vertices of the first layer to each of a plurality of second vertices of a second layer of the mesh, the total number of the plurality of second vertices being greater than the total number of the plurality of first vertices; signaling the volume data based on the displacement vector; 23. A method for video coding comprising:

2. determining second displacement vectors from the plurality of second vertices of the second layer of the mesh and from a plurality of other vertices of the second layer of the mesh; further signaling the volume data based on the second displacement vector; The method for video coding of claim 1 , further comprising:

3. the first layer of the mesh includes polygons defined by straight lines interconnecting each other vertex of the first plurality of vertices; the vertices of the plurality of first vertices are disposed on respective ones of the straight lines interconnecting each of the other vertices of the plurality of first vertices; A method for video coding according to claim 2.

4. the other vertex of the plurality of first vertices is a decoded vertex; the vertex of the plurality of first vertices is an interpolated vertex; the polygon defines a boundary of the first layer of the mesh; A method for video coding according to claim 3.

5. the second layer of meshes includes a plurality of second polygons each defined by second straight lines interconnecting the plurality of second vertices of the second layer of meshes with the other vertices of the plurality of first vertices of the first layer of meshes; A method for video coding according to claim 3.

6. At least one of the plurality of second vertices is within a boundary of the polygon. A method for video coding according to claim 5.

7. each of the plurality of second vertices is within the boundary of the polygon; A method for video coding according to claim 6.

8. the second polygons each lie entirely within the boundary of the polygon; A method for video coding according to claim 5.

9. At least one of the plurality of second vertices is outside the boundary of the polygon. A method for video coding according to claim 5.

10. at least a portion of one of the second polygons is outside the boundary of the polygon; A method for video coding according to claim 9.

11. 1. An apparatus for video coding, comprising: at least one memory configured to store computer program code; at least one processor configured to access the computer program code and to operate as instructed by the computer program code, the computer program code comprising: acquisition code configured to cause the at least one processor to acquire volumetric data of at least one three-dimensional (3D) visual content; derivation code configured to cause the at least one processor to derive a first layer of a mesh comprising a plurality of first vertices from at least one frame of the volumetric data; decision code configured to cause the at least one processor to determine a displacement vector from a vertex of the plurality of vertices of the first layer to each of a plurality of second vertices of a second layer of the mesh, where a total number of the plurality of second vertices is greater than a total number of the plurality of first vertices; signaling code configured to cause the at least one processor to signal the volume data based on the displacement vector; At least one processor, 23. An apparatus for video coding comprising:

12. the determination code is further configured to cause the at least one processor to determine second displacement vectors from the plurality of second vertices of the second layer of the mesh and from a plurality of other vertices of the second layer of the mesh; the signaling code is further configured to cause the at least one processor to further signal the volumetric data based on the second displacement vector. An apparatus for video coding according to claim 11.

13. the first layer of the mesh includes polygons defined by straight lines interconnecting each other vertex of the first plurality of vertices; the vertices of the plurality of first vertices are disposed on respective ones of the straight lines interconnecting each of the other vertices of the plurality of first vertices; An apparatus for video coding according to claim 12.

14. the other vertex of the plurality of first vertices is a decoded vertex; the vertex of the plurality of first vertices is an interpolated vertex; the polygon defines a boundary of the first layer of the mesh; An apparatus for video coding according to claim 13.

15. the second layer of meshes includes a plurality of second polygons each defined by second straight lines interconnecting the plurality of second vertices of the second layer of meshes with the other vertices of the plurality of first vertices of the first layer of meshes; An apparatus for video coding according to claim 13.

16. At least one of the plurality of second vertices is within a boundary of the polygon. An apparatus for video coding according to claim 15.

17. each of the plurality of second vertices is within the boundary of the polygon; An apparatus for video coding according to claim 16.

18. the second polygons each lie entirely within the boundary of the polygon; An apparatus for video coding according to claim 15.

19. At least one of the plurality of second vertices is outside the boundary of the polygon. An apparatus for video coding according to claim 15.

20. On the computer, acquiring volume data of at least one three-dimensional (3D) visual content; deriving a first layer of a mesh comprising a first plurality of vertices from at least one frame of the volumetric data; determining a displacement vector from a vertex of the plurality of vertices of the first layer to each of a plurality of second vertices of a second layer of the mesh, the total number of the plurality of second vertices being greater than the total number of the plurality of first vertices; signaling the volume data based on the displacement vector; A non-transitory computer-readable medium storing a program.

Images