SYSTEM AND METHOD FOR GEOMETRY POINT CLOUD CODING

Abstract

According to one aspect of the present disclosure, a method for decoding a point cloud that is represented in a one-dimension (ID) array that includes a set of points is provided. The method may include parsing, by at least one processor, a bitstream to obtain a first syntax element indicative of an enablement of multiple attribute parameter sets for the point cloud. The method may include determining, by the at least one processor, whether the first syntax element indicates that multiple attribute parameter sets are enabled for the point cloud. In response to determining that the multiple attribute parameter sets are enabled for the point cloud, the method may include decompressing, by the at least one processor, the point cloud based on the multiple attribute parameter sets.

Description

BACKGROUND

Embodiments of the present disclosure relate to point cloud coding.

Point clouds are one of the major three-dimension (3D) data representations, which provide, in addition to spatial coordinates, attributes associated with the points in a 3D world. Point clouds in their raw format require a huge amount of memory for storage or bandwidth for transmission. Furthermore, the emergence of higher resolution point cloud capture technology imposes, in turn, even a higher requirement on the size of point clouds. In order to make point clouds usable, compression is necessary. Two compression technologies have been proposed for point cloud compression/coding (PCC) standardization activities: video-based PCC (V-PCC) and geometry-based PCC (G-PCC). V-PCC approach is based on 3D to two-dimension (2D) projections, while G-PCC, on the contrary, encodes the content directly in 3D space. In order to achieve that, G-PCC utilizes data structures, such as an octree that describes the point locations in 3D space.

SUMMARY

According to one aspect of the present disclosure, a method for decoding a point cloud that is represented in a one-dimension (1D) array that includes a set of points is provided. The method may include parsing, by at least one processor, a bitstream to obtain a first syntax element indicative of an enablement of multiple attribute parameter sets for the point cloud. The method may include determining, by the at least one processor, whether the first syntax element indicates that multiple attribute parameter sets are enabled for the point cloud. In response to determining that the multiple attribute parameter sets are enabled for the point cloud, the method may include decompressing, by the at least one processor, the point cloud based on the multiple attribute parameter sets.

According to another aspect of the present disclosure, a system for decoding a point cloud that is represented in a 1D array that includes a set of points is provided. The system may include at least one processor and memory storing instructions. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to parse a bitstream to obtain a first syntax element indicative of an enablement of multiple attribute parameter sets for the point cloud. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to determine whether the first syntax element indicates that multiple attribute parameter sets are enabled for the point cloud. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to, in response to determining that the multiple attribute parameter sets are enabled for the point cloud, decompress the point cloud based on the multiple attribute parameter sets.

According to a further aspect of the present disclosure, a method for encoding a point cloud that is represented in a 1D array that includes a set of points is provided. The method may include generating, by at least one processor, a first syntax element indicative of multiple attribute parameter sets for the point cloud. The method may include inputting, by the at least one processor, the first syntax element into a bitstream. In response to the multiple attribute parameter sets being enabled for the point cloud, the method may include compressing, by the at least one processor, the point cloud based on the multiple attribute parameter sets.

According to a further aspect of the present disclosure, a system for encoding a point cloud that is represented in a 1D array that includes a set of points is provided. The system may include at least one processor and memory storing instructions. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to generate a first syntax element indicative of multiple attribute parameter sets for the point cloud. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to input the first syntax element into a bitstream. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to, in response to the multiple attribute parameter sets being enabled for the point cloud, compressing the point cloud based on the multiple attribute parameter sets.

These illustrative embodiments are mentioned not to limit or define the present disclosure, but to provide examples to aid understanding thereof. Additional embodiments are described in the Detailed Description, and further description is provided there.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable a person skilled in the pertinent art to make and use the present disclosure.

FIG. 1 illustrates a block diagram of an exemplary encoding system, according to some embodiments of the present disclosure.

FIG. 2 illustrates a block diagram of an exemplary decoding system, according to some embodiments of the present disclosure.

FIG. 3 illustrates a detailed block diagram of an exemplary encoder in the encoding system in FIG. 1, according to some embodiments of the present disclosure.

FIG. 4 illustrates a detailed block diagram of an exemplary decoder in the decoding system in FIG. 2, according to some embodiments of the present disclosure.

FIGS. 5A and 5B illustrate an exemplary octree structure of G-PCC and the corresponding digital representation, respectively, according to some embodiments of the present disclosure.

FIG. 6 illustrates an exemplary structure of cube and the relationship with neighboring cubes in an octree structure of G-PCC, according to some embodiments of the present disclosure.

FIG. 7 illustrates an exemplary 1D array of points representing a point cloud, a set of candidate points, and a set of prediction points, according to some embodiments of the present disclosure.

FIG. 8 illustrates an exemplary hierarchy of parameter sets of G-PCC, according to some embodiments of the present disclosure.

FIG. 9 illustrates a flow chart of an exemplary method for encoding a point cloud, according to some embodiments of the present disclosure.

FIG. 10 illustrates a flow chart of an exemplary method for decoding a point cloud, according to some embodiments of the present disclosure.

Embodiments of the present disclosure will be described with reference to the accompanying drawings.

DETAILED DESCRIPTION

Although some configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the pertinent art will recognize that other configurations and arrangements can be used without departing from the spirit and scope of the present disclosure. It will be apparent to a person skilled in the pertinent art that the present disclosure can also be employed in a variety of other applications.

It is noted that references in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” “some embodiments,” “certain embodiments,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of a person skilled in the pertinent art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

In general, terminology may be understood at least in part from usage in context. For example, the term “one or more” as used herein, depending at least in part upon context, may be used to describe any feature, structure, or characteristic in a singular sense or may be used to describe combinations of features, structures or characteristics in a plural sense. Similarly, terms, such as “a,” “an,” or “the,” again, may be understood to convey a singular usage or to convey a plural usage, depending at least in part upon context. In addition, the term “based on” may be understood as not necessarily intended to convey an exclusive set of factors and may, instead, allow for existence of additional factors not necessarily expressly described, again, depending at least in part on context.

Various aspects of point cloud coding systems will now be described with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various modules, components, circuits, steps, operations, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, firmware, computer software, or any combination thereof. Whether such elements are implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system. The techniques described herein may be used for various point cloud coding applications. As described herein, point cloud coding includes both encoding and decoding a point cloud.

A point cloud is composed of a collection of points in a 3D space. Each point in the 3D space is associated with a geometry position together with the associated attribute information (e.g., color, reflectance, intensity, classification, etc.). In order to compress the point cloud data efficiently, the geometry of a point cloud can be compressed first, and then the corresponding attributes, including color or reflectance, can be compressed based upon the geometry information according to a point cloud coding technique, such as G-PCC. G-PCC has been widely used in virtual reality/augmented reality (VR/AR), telecommunication, autonomous vehicle, etc., for entertainment and industrial applications, e.g., light detection and ranging (LiDAR) sweep compression for automotive or robotics and high-definition (HD) map for navigation. Moving Picture Experts Group (MPEG) released the first version G-PCC standard, and Audio Video Coding Standard (AVS) is also developing a G-PCC standard.

The existing G-PCC standards, however, cannot work well for a wide range of PCC inputs for many different applications. For example, besides the representation of levels (or coefficients in some cases), the representation of other information (e.g., parameters) used for G-PCC may be coded in the forms of syntax elements in the bitstream as well. Since G-PCC is organized in different levels by dividing a collection of points into different pieces (e.g., sequence, slices, etc.) associated with different properties (e.g., geometry, attributes, etc.), the parameter sets are also arranged in different levels (e.g., sequence-level, property-level, slice-level, etc.), for example, in the different headers. Moreover, multiple condition checks may be required for parsing some syntax elements in G-PCC, which further increases the complexity of organizing and parsing the representation of syntax elements.

To improve the flexibility and generality of point cloud coding, the present disclosure provides various novel schemes of syntax element representation and organization, which are compatible with any suitable G-PCC standards, including, but not limited to, AVS G-PCC standards and MPEG G-PCC standards.

FIG. 1 illustrates a block diagram of an exemplary encoding system 100, according to some embodiments of the present disclosure. FIG. 2 illustrates a block diagram of an exemplary decoding system 200, according to some embodiments of the present disclosure. Each system 100 or 200 may be applied or integrated into various systems and apparatuses capable of data processing, such as computers and wireless communication devices. For example, system 100 or 200 may be the entirety or part of a mobile phone, a desktop computer, a laptop computer, a tablet, a vehicle computer, a gaming console, a printer, a positioning device, a wearable electronic device, a smart sensor, a virtual reality (VR) device, an argument reality (AR) device, or any other suitable electronic devices having data processing capability. As shown in FIGS. 1 and 2, system 100 or 200 may include a processor 102, a memory 104, and an interface 106. These components are shown as connected one to another by a bus, but other connection types are also permitted. It is understood that system 100 or 200 may include any other suitable components for performing functions described here.

Processor 102 may include microprocessors, such as graphic processing unit (GPU), image signal processor (ISP), central processing unit (CPU), digital signal processor (DSP), tensor processing unit (TPU), vision processing unit (VPU), neural processing unit (NPU), synergistic processing unit (SPU), or physics processing unit (PPU), microcontroller units (MCUs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout the present disclosure. Although only one processor is shown in FIGS. 1 and 2, it is understood that multiple processors can be included. Processor 102 may be a hardware device having one or more processing cores. Processor 102 may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Software can include computer instructions written in an interpreted language, a compiled language, or machine code. Other techniques for instructing hardware are also permitted under the broad category of software.

Memory 104 can broadly include both memory (a.k.a, primary/system memory) and storage (a.k.a. secondary memory). For example, memory 104 may include random-access memory (RAM), read-only memory (ROM), static RAM (SRAM), dynamic RAM (DRAM), ferro-electric RAM (FRAM), electrically erasable programmable ROM (EEPROM), compact disc read-only memory (CD-ROM) or other optical disk storage, hard disk drive (HDD), such as magnetic disk storage or other magnetic storage devices, Flash drive, solid-state drive (SSD), or any other medium that can be used to carry or store desired program code in the form of instructions that can be accessed and executed by processor 102. Broadly, memory 104 may be embodied by any computer-readable medium, such as a non-transitory computer-readable medium. Although only one memory is shown in FIGS. 1 and 2, it is understood that multiple memories can be included.

Interface 106 can broadly include a data interface and a communication interface that is configured to receive and transmit a signal in a process of receiving and transmitting information with other external network elements. For example, interface 106 may include input/output (I/O) devices and wired or wireless transceivers. Although only one memory is shown in FIGS. 1 and 2, it is understood that multiple interfaces can be included.

Processor 102, memory 104, and interface 106 may be implemented in various forms in system 100 or 200 for performing point cloud coding functions. In some embodiments, processor 102, memory 104, and interface 106 of system 100 or 200 are implemented (e.g., integrated) on one or more system-on-chips (SoCs). In one example, processor 102, memory 104, and interface 106 may be integrated on an application processor (AP) SoC that handles application processing in an operating system (OS) environment, including running point cloud encoding and decoding applications. In another example, processor 102, memory 104, and interface 106 may be integrated on a specialized processor chip for point cloud coding, such as a GPU or ISP chip dedicated to graphic processing in a real-time operating system (RTOS).

As shown in FIG. 1, in encoding system 100, processor 102 may include one or more modules, such as an encoder 101. Although FIG. 1 shows that encoder 101 is within one processor 102, it is understood that encoder 101 may include one or more sub-modules that can be implemented on different processors located closely or remotely with each other. Encoder 101 (and any corresponding sub-modules or sub-units) can be hardware units (e.g., portions of an integrated circuit) of processor 102 designed for use with other components or software units implemented by processor 102 through executing at least part of a program, i.e., instructions. The instructions of the program may be stored on a computer-readable medium, such as memory 104, and when executed by processor 102, it may perform a process having one or more functions related to point cloud encoding, such as voxelization, transformation, quantization, arithmetic encoding, etc., as described below in detail.

Similarly, as shown in FIG. 2, in decoding system 200, processor 102 may include one or more modules, such as a decoder 201. Although FIG. 2 shows that decoder 201 is within one processor 102, it is understood that decoder 201 may include one or more sub-modules that can be implemented on different processors located closely or remotely with each other. Decoder 201 (and any corresponding sub-modules or sub-units) can be hardware units (e.g., portions of an integrated circuit) of processor 102 designed for use with other components or software units implemented by processor 102 through executing at least part of a program, i.e., instructions. The instructions of the program may be stored on a computer-readable medium, such as memory 104, and when executed by processor 102, it may perform a process having one or more functions related to point cloud decoding, such as arithmetic decoding, dequantization, inverse transformation, reconstruction, synthesis, as described below in detail.

FIG. 3 illustrates a detailed block diagram of exemplary encoder 101 in encoding system 100 in FIG. 1, according to some embodiments of the present disclosure. As shown in FIG. 3, encoder 101 may include a coordinate transform module 302, a voxelization module 304, a geometry analysis module 306, and an arithmetic encoding module 308, together configured to encode positions associated with points of a point cloud into a geometry bitstream (i.e., geometry encoding). As shown in FIG. 3, encoder 101 may also include a color transform module 310, an attribute transform module 312, a quantization module 314, and an arithmetic encoding module 316, together configured to encode attributes associated with points of a point cloud into an attribute bitstream (i.e., attribute encoding). It is understood that each of the elements shown in FIG. 3 is independently shown to represent characteristic functions different from each other in a point cloud encoder, and it does not mean that each component is formed by the configuration unit of separate hardware or single software. That is, each element is included to be listed as an element for convenience of explanation, and at least two of the elements may be combined to form a single element, or one element may be divided into a plurality of elements to perform a function. It is also understood that some of the elements are not necessary elements that perform functions described in the present disclosure but instead may be optional elements for improving performance. It is further understood that these elements may be implemented using electronic hardware, firmware, computer software, or any combination thereof. Whether such elements are implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on encoder 101. It is still further understood that the modules shown in FIG. 3 are for illustrative purposes only, and in some examples, different modules may be included in encoder 101 for point cloud encoding.

As shown in FIG. 3, geometry positions and attributes associated with points may be encoded separately. A point cloud may be a collection of points with positions X_k=(x_k, y_k, z_k), k=1, . . . , K, where K is the number of points in the point cloud, and attributes A_k=(A_1k, A_2k, . . . , A_Dk), k=1, . . . , K, where D is the number of attributes for each point. In some embodiments, attribute coding depends on decoded geometry. As a consequence, point cloud positions may be coded first. Since geometry positions may be represented by floating-point numbers in an original coordinate system, coordinate transform module 302 and a voxelization module 304 may be configured to perform a coordinate transformation followed by voxelization that quantizes and removes duplicate points. The process of position quantization, duplicate point removal, and assignment of attributes to the remaining points is called voxelization. The voxelized point cloud may be represented using, for example, an octree structure in a lossless manner. Geometry analysis module 306 may be configured to perform geometry analysis using, for example, the octree or trisoup scheme. Arithmetic encoding module 308 may be configured to arithmetically encode the resulting structure from geometry analysis module 306 into the geometry bitstream.

In some embodiments, geometry analysis module 306 is configured to perform geometry analysis using the octree scheme. Under the octree scheme, a cubical axis-aligned bounding box B may be defined by the two extreme points (0,0,0) and (2^d, 2^d, 2^d) where d is the maximum size of the given point cloud along the x, y, or z direction. All point cloud points may be included in this defined cube. A cube may be divided into eight sub-cubes, which creates the octree structure allowing one parent to have 8 children, and an octree structure may then be built by recursively subdividing sub-cubes, as shown in FIG. 5A. As shown in FIG. 5B, an 8-bit code may be generated by associating a 1-bit value with each sub-cube to indicate whether it contains points (i.e., full and has value 1) or not (i.e., empty and has value 0). Only full sub-cubes with a size greater than 1 (i.e., non-voxels) may be further subdivided. The geometry information (x, y, z) for one position may be represented by this defined octree structure. Since points may be duplicated, multiple points may be mapped to the same sub-cube of size 1 (i.e., the same voxel). In order to handle such a situation, the number of points for each sub-cube of dimension 1 is also arithmetically encoded. By construction of the octree, a current cube associated with a current node may be surrounded by six cubes of the same depth sharing a face with it. Depending on the location of the current cube, one cube may have up to six same-sized cubes to share one face, as shown in FIG. 6. In addition, the current cube may also have some neighboring cubes which share lines or points with the current cube.

Referring back to FIG. 3, as to attribute encoding, optionally, color transform module 310 may be configured to convert red/green/blue (RGB) color attributes of each point to YCbCr color attributes if the attributes include color. Attribute transform module 312 may be configured to perform attribute transformation based on the results from geometry analysis module 306 (e.g., using the octree scheme), including but not limited to, the region adaptive hierarchical transform (RAHT), interpolation-based hierarchical nearest-neighbor prediction (predicting transform), and interpolation-based hierarchical nearest-neighbor prediction with an update/lifting step (lifting transform). Optionally, quantization module 314 may be configured to quantize the transformed coefficients of attributes from attribute transform module 312 to generate quantization levels of the attributes associated with each point to reduce the dynamic range. Arithmetic encoding module 316 may be configured to arithmetically encode the resulting transformed coefficients of attributes associated with each point or the quantization levels thereof into the attribute bitstream.

In some embodiments, a prediction may be formed from neighboring coded attributes, for example, in predicting transform and lifting transform by attribute transform module 312. Then, the difference between the current attribute and the prediction may be coded. According to some aspects of the present disclosure, in the AVS G-PCC standard, after the geometry positions are coded, a Morton code or Hilbert code may be used to convert a point cloud in a 3D space (e.g., a point cloud cube) into a 1D array, as shown in FIG. 7. Each position in the cube will have a corresponding Morton or Hilbert code, but some positions may not have any corresponding point cloud attribute. In other words, some positions may be empty. The attribute coding may follow the predefined Morton order or Hilbert order. A predictor may be generated from the previous coded points in the 1D array following the Morton order or Hilbert order. The attribute difference between the current point and its prediction points may be encoded into the bitstream. In some embodiments, the point cloud in the 3D space (e.g., a point cloud cube) is converted into a 1D array without any pre-defined order, but instead in its native input order, for example, the order in which the point cloud data is collected. That is, in some examples, the attribute coding may follow the native input order of the point cloud, instead of the predefined Morton order or Hilbert order. In other words, the order followed by the points in the 1D array may be either a Morton order, a Hilbert order, or the native input order.

As shown in FIG. 7, to reduce the memory usage, some predefined numbers may be specified to limit the number of neighboring points that can be used in generating the prediction. For example, only at most M points among previous at most N consecutively coded points may be used for coding the current attribute. That is, a set of n candidate points may be used as the candidates to select a set of m prediction points (m≤n) for predicting the current point in attribute coding. The number n of candidate points in the set is equal to or smaller than the maximum number N of candidate points (n≤N), and the number m of prediction points in the set is equal to or smaller than the maximum number M of prediction points (m≤M). As shown in FIG. 7, if the number of neighboring points prior to the current point in the 1D array following the Morton order, the Hilbert order, or the native input order is larger than the maximum number N of candidate points, then the number n of candidate points in the set of candidate points for the current point (shaded in grey) is equal to the maximum number N; if the number of neighboring points prior to the current point in the 1D array following the Morton order, the Hilbert order, or the native input order is larger than or equal to the maximum number N of candidate points, then the number n of candidate points in the set of candidate points for the current point (shaded in grey) is smaller to the maximum number N, then all the neighboring points prior to the current point are used as the set of candidate points for the current point. In FIG. 7, the maximum number M of prediction points is set to be 3, and a set of 3 prediction points (P, bolded and underlined) may be selected from the set of n candidate points, for example, based on the positions associated with the n candidate points and the current points (e.g., the distances between each candidate point and the current point).

In some embodiments, M and N are set as a fixed number of 3 and 128, respectively. If more than 128 points before the current point are already coded, only 3 out of the previous 128 neighboring points could be used to form attribute predictors (prediction points) according to a predefined order. If there are less than 128 coded points before the current point, all coded points before the current point will be used as candidate points to find the prediction points. Among the previous up to 128 candidate points, up to 3 prediction points are selected, which have the closest “distance” (e.g., Euclidean distance) between these candidate points and the current point. The Euclidean distance d as one example may be defined as follows, while other distance metrics can also be used in other examples:

$\begin{array}{cc}d=❘x1-x2❘+❘y1-y2❘+❘z1-z2❘,& \left(1\right)\end{array}$

where (x1, y1, z1) and (x2, y2, z2) are the coordinates of the current point and the candidate point along the Morton order, the Hilbert order, or the native input order, respectively. Once m prediction points (e.g., the 3 closest candidate points) have been selected, a weighted attribute average from these m points may be formed as the predictor to code the attribute of the current point, according to some embodiments. It is understood that in some examples, the prediction points may be selected from the candidate points that are in the cubes sharing the same face/line/point with the current point cloud.

Since the set of n candidate points needs to be stored in the memory and traversed in order to select the set of m prediction points for coding the attributes associated with the current position, the maximum number M of candidate points is introduced to limit the size of memory and amount of computation resources that may be occupied by the candidate points storage and searching.

According to some aspects of the present disclosure, the difference in attribute values between the current point and its predictor may be referred to as a “residual.” Depending on the application, PCC can be either lossless or lossy. Hence, the residual may or may not be quantized by using the predefined quantization process. According to the present disclosure, the residual without or with quantization may be referred to as a “level,” which is a signed integer (e.g., a positive or negative integer value) coded into the bitstream.

There are three color attributes for each point, which come from the three color components. If the levels for all the three color components are zeros, this point is called a zero-level point. Otherwise, if there is at least one non-zero level for one color component with the point, this point is called a non-zero level point. The number of consecutive zero-level points is referred to as a “zero-run length.” The zero-run length values and levels for non-zero level points are coded into the bitstream. More specifically, before coding the first point, encoder 101 may set the zero-run length counter as zero.

Starting from the first point along the predefined coding order, the residuals between the three color predictors and their corresponding color attributes for the current point can be obtained. Then, the corresponding levels for the three components of the current point can also be obtained. If the current point is a zero-level point, encoder 101 may increase the zero-run length value by one, and the process proceeds to the next point. If the current point is a non-zero level point, the zero-run length value will be coded first, and then the three color levels for this non-zero level point will be coded right after. After the level coding of a non-zero level point, the zero-run length value will be reset to zero, and the process proceeds to the next point till finishing all points. On the decoding side, decoder 201 may decode the zero-run length value, and the three color levels corresponding to the number of zero-run length points are set as zero. Then, the levels for the non-zero level point are decoded, and then the next zero-run length value is decoded. This process continues until all points are decoded. Tables 1 and 2 illustrate example syntax elements used for color-residual coding and color-level coding, respectively.

TABLE 1
Syntax elements for color-residual coding
color_residual_coding( ) { Descriptor
color_first_comp_zero      ae(v)
if (!color_first_comp_zero) {
color_component[0] = (2*coded_level_sign −1)
*|coded_level_coding (true) + 1|
color_component[1] = coded_level_coding (false)
color_component[2] = coded_level_coding (false)
} else {
color_component[0] = 0
color_second_comp_zero     ae(v)
If (!color_second_comp_zero) {
color_component[1] = (2*coded_level_sign −1)
*|coded_level_coding (true) + 1
color_component[2] = coded_level_coding (false)
else {
color_component[1] = 0
color_component[2] = (2*coded_level_sign −1)
*|coded_level_coding (true) + 1|
}
}
}

TABLE 2
Syntax elements for color-level coding
coded_level_coding (isComponentNoneZero) { Descriptor
coded_level_equal_zero           ae(v)
if (!coded_level_equal_zero)
coded_level_sign                 ae(v)
if (!coded_level_equal_zero) {
coded_level_sign                 ae(v)
coded_level_gt1                  ae(v)
if (coded_level_gt1) {
coded_level_minus2_parity        ae(v)
coded_level_minus2_div2_gt0      ae(v)
if (coded_level_minus2_div2_gt0)
coded_level_minu2_div2_minus1    ae(v)
}
}
}

For a non-zero level point, there is at least one non-zero level among the three components. The values of the three color-components are coded in the color_residual_coding( ) syntax element. Several one-bit flags plus the remainder of the absolute level may be coded to represent levels of the three color-components. The absolute level or absolute level of color residual minus one may be coded in the function coded_level_coding( ) which is also referred to hereinafter as the “coded level.”

According to some aspects of the present disclosure, a first flag (color_first_comp_zero) is coded to indicate whether the first component of color is zero or not; if the first color-component is zero, a second flag (color_second_comp_zero) is coded to indicate whether the second color-component of color is zero; if the second component of color is zero, the absolute level minus one and the sign of the third component will be coded according to the following coded-level technique.

For instance, a first flag is coded to indicate whether the first color-component of color is zero; if the first color-component is zero, a second flag may be coded to indicate whether the second-color component is zero; if the second component of color is not zero, the absolute level minus one and sign of the second color-component and the absolute level and sign of the third color-component will be coded according to the following coded-level technique.

According to another aspect of the present disclosure, a first flag may be coded to indicate whether the color-first component is zero; if the first color-component is not zero, the absolute level minus one and the sign of the first color-component, as well as the absolute levels and signs of the second and third color-components will be coded according to the following coded-level technique.

For example, the first flag (coded_level_equal_zero) is coded to indicate whether the code-level is zero or not; if the coded level is the absolute level of one color-component minus one, e.g., namely, when the isComponentNoneZero flag is set to “true,” the sign (coded_level_sign) of the level of this color-component will be coded. On the other hand, if the first flag indicates that the coded level is not zero, and if the coded level is the absolute level of one color-component, e.g., when the isComponentNoneZero flag is set to “false,” the sign of the level of this color-component will be coded. The second flag (coded_level_gt1) will be coded to indicate if the coded level is greater than one; if the coded level is greater than one, the parity of the coded level minus two is coded, and the third flag (coded_level_minus2_div2_gt0) will be coded to indicate whether the coded level minus two divided by two is greater than zero; if the coded level minus two divided by two is greater than zero, the coded level minus two divided by two minus one will be coded.

Referring to Tables 1 and 2, a color_first_comp_zero value equal to 0 specifies that the absolute coded level for the first component of color is not zero. A color_first_comp_zero value equal to 1 specifies that the absolute coded level for the first component is zero.

A color_second_comp_zero value equal to 0 specifies that the absolute coded level for the second component of color is not zero. A color_second_comp_zero value equal to 1 specifies that the absolute coded level for the second component is zero.

A coded_level_equal_zero value equal to 0 specifies that the absolute coded level for this component is not zero. A coded_level_equal_zero value equal to 1 specifies that the absolute coded level for this component is zero.

A coded_level_gt1 value equal to 0 specifies that the coded level for this component is one. A coded_level_gt1 value equal to 1 specifies that the coded level for this component is greater than one. When a coded_level_gt1 value is not included in the bitstream, decoder 201 may infer the coded_level_gt1 value is equal to 0.

A coded_level_minus2_parity specifies the parity of the coded level minus two for the current color-component. A coded_level_minus2_parity value equal to 0 specifies that the current coded level minus two is an even number. A coded_level_minus2_parity value equal to 1 specifies that the current coded level minus two is an odd number. When a coded_level_minus2_parity value is not present in the bitstream, decoder 201 may infer that coded_level_minus2_parity value is equal to 0.

A coded_level_minus2_div2_gt0 value equal to 0 specifies that the coded level minus two dividing two is zero. A coded_level_minus2_div2_gt0 value equal to 1 specifies that the coded level minus two divided by two is greater than zero. When a coded_level_minus2_div2_gt0 value is not present in the bitstream, decoder 201 may infer the coded_level_minus2_div2_gt0 value is equal to 0.

A coded_level_minu2_div2_minus1 syntax element specifies the value of the coded level minus two divided by two minus one. When a coded_level_minu2_div2_minus1 syntax is not present in the bitstream, decoder 201 may infer coded_level_minu2_div2_minus1 syntax element is equal to 0.

A coded_level and a coded_level_sign are the return values of function coded_level_coding (isComponentminusOne), which represent the coded level. The coded level may include the absolute level of the color residual or the absolute level of the color residual minus one and the sign of non-zero color residual, as indicated below according to expression (2).

$\begin{array}{cc}\mathrm{coded\_level}=\left(2*\mathrm{coded\_level}\mathrm{\_sign}-1\right)*(\mathrm{coded\_level}\mathrm{\_equal}\mathrm{\_zero}?0:1+\left(\mathrm{coded\_level}\mathrm{\_gt1}+\mathrm{coded\_level}\mathrm{\_minus2}\mathrm{\_parity}+\left(\mathrm{coded\_level}\mathrm{\_minus2}\mathrm{\_div2}\mathrm{\_gt0}+\mathrm{coded\_level}\mathrm{\_minu2}\mathrm{\_div2}\mathrm{\_minus}1\right)<<1\right).& \left(2\right)\end{array}$

The residual levels of three color components, e.g., color_component[idx], where idx is an index from 0 to 2, are calculated from color_residual_coding( ).

Moreover, the zero-run length of the reflectance level and the non-zero reflectance-level may be coded into the bitstream. More specifically, before coding the first point, encoder 101 may set the zero-run length counter as zero. Starting from the first point along the predefined coding order, the residuals between the predictors and corresponding original points are obtained. Then, the corresponding reflectance-levels may be obtained. If the current reflectance-level is zero, encoder 101 increases the value of the zero-run length counter by one, and the process proceeds to the next point. If the reflectance-level is not zero, encoder 101 may code the zero-run length, followed by coding the non-zero reflectance-level. After coding a non-zero reflectance level, encoder 101 may reset the zero-run length counter to zero, and the process proceeds to the next point. On the decoding side, decoder 201 may decode the zero-run length, and the reflectance-levels corresponding to the number of zero-run length points are set as zero. Then, decoder 201 may decode the non-zero reflectance level, followed by decoding the next number of zero-run length. This process may continue until all points are decoded.

For a non-zero reflectance-level, if the current point is not a duplicated point, the sign of the reflectance-level is coded with a “residual_sign” syntax element. Then, an “abs_level_minus1_parity” syntax element, which indicates the parity of the absolute level minus one, may be coded by encoder 101. Another syntax element “abs_level_minus1_div2_gt0” may be coded to indicate whether the value of the absolute level minus one divided by two is greater than zero; if abs_level_minus1_div2_gt0 is greater than zero, encoder 101 may encode an “abs_level_minus1_div2_gt1” syntax element to indicate whether the value of the absolute level minus one divided by two is greater than one; if the abs_level_minus1_div2_gt1 syntax element is greater than 1, encoder 101 may encode “abs_level_minu1_div2_minus2” syntax element to indicate the value of the absolute level minus one divided by two minus two. Table 3 shown below illustrates example reflectance-level coding syntax elements.

TABLE 3
Reflectance-level coding syntax elements
attribute_data_reflectance( ) {  Descriptor
zero_run_length_code(useGolomb)
for( i = 0; i < pointCloudNum; i++ ) {
if (residual_zero_run_length) {
-- residual_zero_run_length
} else {
if ( lisDuplicatePoint) {
residual_sign                    ae(1)
}
abs_level_minus1_parity          ae(v)
abs_level_minus1_div2_gt0        ae(v)
if (abs_level_minus1_div2_gt0) {
abs_level_minus1_div2_gt1        ae(v)
if (abs_level_minus1_div2_gt1) {
abs_level_minu1_div2_minus2      ae(v)
}
}
zero_run_length_code(useGolomb)
}
}
termination_bit_one /* equals to 1 */ ae(v)
}

Referring to Table 3, the abs_level_minus1_parity syntax element specifies the parity of absolute reflectance level minus one. An abs_level_minus1_parity value equal to 0 may indicate that the absolute reflectance level minus one is an even number; on the other hand, an abs_level_minus1_parity value equal to 1 may indicate that the absolute reflectance level minus one is an odd number.

An abs_level_minus1_div2_gt0 value equal to 0 may indicate that the value of the absolute reflectance level minus one divided by two is zero. An abs_level_minus1_div2_gt0 value equal to 1 may indicate that the value of the absolute reflectance level minus one divided by two is greater than zero. When not present, decoder 201 may infer that the value of abs_level_minus1_div2_got0 is equal to 0.

An abs_level_minus1_div2_gt1 value equal to 0 may indicate that the value of the absolute reflectance level minus one divided by two is one. An abs_level_minus1_div2_gt1 value equal to 1 may indicate that the value of the absolute reflectance level minus one divided by two is greater than one. When not present in the bitstream, decoder 201 may infer the value of the abs_level_minus1_div2_gt1 is equal to 0.

The abs_level_minu1_div2_minus2 syntax value may indicate the value of the absolute reflectance level minus 1 divided by two minus two. When not present, decoder 201 may infer that the value of abs_level_minu1_div2_minus2 is equal to 0.

A residual_sign value equal to 0 may indicate that the sign of the reflectance level is negative; on the other hand, a residual_sign value equal to 1 may indicate that the sign of the reflectance level is positive. When not present in the bitstream, decoder 201 may infer that the value of residual_sign is equal to 1. The reflectance may be calculated according to expression (3).

$\begin{array}{cc}\mathrm{Reflectance}=\left(2*\mathrm{residual\_sign}-1\right)*\left(1+\mathrm{abs\_level}\mathrm{\_minus1}\mathrm{\_parity}+\left(\mathrm{abs\_level}\mathrm{\_minus1}\mathrm{\_div2}\mathrm{\_gt0}+\mathrm{abs\_level}\mathrm{\_minus1}\mathrm{\_div2}\mathrm{\_gt1}+\mathrm{abs\_level}\mathrm{\_minul}\mathrm{\_div2}\mathrm{\_minus2}\right)<<1\right).& \left(3\right)\end{array}$

Still further, encoder 101 may encode the value of the zero-run length into the bitstream. For example, encoder 101 may encode the first syntax zero_run_length_level_equal_zero (e.g., a first syntax element) into the bitstream to indicate whether the zero-run length is equal to zero; if it is not zero, encoder 101 may encode the zero_run_length_level_equal_one syntax element (e.g., a second syntax element) to indicate whether the zero-run length is equal to one; if it is not one, encoder 101 may encode the zero_run_length_level_equal_two syntax element (e.g., a third syntax element) into the bitstream to indicate whether the zero-run length is equal to two; if it is not two, encoder 101 may encode the zero_run_length_level_minus3_parity syntax element (e.g., fourth syntax element) and the zero_run_length_level_minus3_div2 syntax element (e.g., a fifth syntax element) into the bitstream to indicate the parity of the zero-run length minus three and the value of the zero-run length minus three divided by two, respectively. Examples of the syntax elements used for zero-run length encoding are provided below in Table 4.

TABLE 4
Zero-run length syntax elements
zero_run_length_code(useGolomb) { Descriptor
zero_run_length_level_equal_zero ae(v)
if (!zero_run_length_level_equal_zero) {
zero_run_length_level_equal_one  ae(v)
if (!zero_run_length_level_equal_one) {
zero_run_length_level_equal_two  ae(v)
if (!run_length_level_equal_two) {
zero_run_length_level_minus3_parity ae(v)
zero_run_length_level_minus3_div2 ae(v)
}
}
}
if (useGolomb )
run_length_LSB                   ae(v)

Referring to Table 4, a zero_run_length_level_minus3_parity specifies the parity of the zero-run length level minus three. zero_run_length_level_minus3_parity equal to 0 specifies that the zero-run length level minus three is an even number. zero_run_length_level_minus3_parity equal to 1 specifies that the zero-run length level minus three is an odd number. When not present, it is inferred to be equal to 0.

A zero_run_length_level_equal_zero value equal to 0 may indicate that the zero-run length level is not zero; on the other hand, a zero_run_length_level_equal_zero value equal to 1 specifies that the zero-run length level is zero.

A zero_run_length_level_equal_one value equal to 0 may indicate that the zero-run length level is not one; on the other hand, a zero_run_length_level_equal_one value equal to 1 specifies that the zero-run length level is one.

A zero_run_length_level_equal_two value equal to 0 may indicate that the zero-run length level is not two; on the other hand, a zero_run_length_level_equal_two value equal to 1 may indicate that the zero-run length level is two.

A zero_run_length_level_minus3_div2 syntax element may indicate the value of the zero-run length level minus three divided by two. When not present in the bitstream, decoder 201 may infer that the value of the zero_run_length_level_minus3_div2 syntax element is equal to 0. The variable zero_run_length_level may be calculated according to expression (4).

$\begin{array}{cc}\mathrm{zero\_run}\mathrm{\_length}\mathrm{\_level}=\mathrm{zero\_run}\mathrm{\_length}\mathrm{\_level}\mathrm{\_equal}\mathrm{\_zero}?0:\left(\mathrm{zero\_run}\mathrm{\_length}\mathrm{\_level}\mathrm{\_equal}\mathrm{\_one}?1:\left(\mathrm{zero\_run}\mathrm{\_length}\mathrm{\_level}\mathrm{\_equal}\mathrm{\_two}?2:\left(3+\mathrm{zero\_run}\mathrm{\_length}\mathrm{\_level}\mathrm{\_minus3}\mathrm{\_parity}+\left(\mathrm{zero\_run}\mathrm{\_length}\mathrm{\_level}\mathrm{\_minus3}\mathrm{\_div2}<<1\right)\right)\right)\right).& \left(4\right)\end{array}$

The value of zero-run_length may be calculated according to expression (5)

$\begin{array}{cc}\mathrm{zero\_run}\mathrm{\_length}=\mathrm{useGolomb}?\left(2\star \mathrm{zero\_run}\mathrm{\_lenght}\mathrm{\_level}+\mathrm{zero\_run}\mathrm{\_length}\mathrm{\_LSB}\right)\text{⁠}:\mathrm{zero\_run}\mathrm{\_length}\mathrm{\_level}.& \left(5\right)\end{array}$

FIG. 4 illustrates a detailed block diagram of exemplary decoder 201 in decoding system 200 in FIG. 2, according to some embodiments of the present disclosure. As shown in FIG. 4, decoder 201 may include an arithmetic decoding module 402, a geometry synthesis module 404, a reconstruction module 406, and a coordinate inverse transform module 408, together configured to decode positions associated with points of a point cloud from the geometry bitstream (i.e., geometry decoding). As shown in FIG. 4, decoder 201 may also include an arithmetic decoding module 410, a dequantization module 412, an attribute inverse transform module 414, and a color inverse transform module 416, together configured to decode attributes associated with points of a point cloud from the attribute bitstream (i.e., attribute decoding). It is understood that each of the elements shown in FIG. 4 is independently shown to represent characteristic functions different from each other in a point cloud decoder, and it does not mean that each component is formed by the configuration unit of separate hardware or single software. That is, each element is included to be listed as an element for convenience of explanation, and at least two of the elements may be combined to form a single element, or one element may be divided into a plurality of elements to perform a function. It is also understood that some of the elements are not necessary elements that perform functions described in the present disclosure but instead may be optional elements for improving performance. It is further understood that these elements may be implemented using electronic hardware, firmware, computer software, or any combination thereof. Whether such elements are implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on decoder 201. It is still further understood that the modules shown in FIG. 4 are for illustrative purposes only, and in some examples, different modules may be included in decoder 201 for point cloud decoding.

When a point cloud bitstream (e.g., a geometry bitstream or an attribute bitstream) is input from a point cloud encoder (e.g., encoder 101), the input bitstream may be decoded by decoder 201 in a procedure opposite to that of the point cloud encoder. Thus, the details of decoding that are described above with respect to encoding may be skipped for ease of description. Arithmetic decoding modules 402 and 410 may be configured to decode the geometry bitstream and attribute bitstream, respectively, to obtain various information encoded into the bitstream. For example, arithmetic decoding module 410 may decode the attribute bitstream to obtain the attribute information associated with each point, such as the quantization levels or the coefficients of the attributes associated with each point. Optionally, dequantization module 412 may be configured to dequantize the quantization levels of attributes associated with each point to obtain the coefficients of attributes associated with each point. Besides the attribute information, arithmetic decoding module 410 may parse the bitstream to obtain various other information (e.g., in the form of syntax elements), such as the syntax element indicative of the order followed by the points in the 1D array for attribute coding.

Inverse attribute transform module 414 may be configured to perform inverse attribute transformation, such as inverse RAHT, inverse predicting transform, or inverse lifting transform, to transform the data from the transform domain (e.g., coefficients) back to the attribute domain (e.g., luma and/or chroma information for color attributes). Optionally, color inverse transform module 416 may be configured to convert YCbCr color attributes to RGB color attributes.

As to the geometry decoding, geometry synthesis module 404, reconstruction module 406, and coordinate inverse transform module 408 of decoder 201 may be configured to perform the inverse operations of geometry analysis module 306, voxelization module 304, and coordinate transform module 302 of encoder 101, respectively.

Consistent with the scope of the present disclosure, encoder 101 and decoder 201 may be configured to adopt various novel schemes of syntax element representation and organization, as disclosed herein, to improve the flexibility and generality of point cloud coding.

According to some aspects of the present disclosure, various attribute-presence syntax elements are introduced at different levels to control the enablement/disablement of all attributes or an individual attribute in point cloud coding. In some embodiments, the different parameters under the same condition check at the same level (e.g., associated with the same attribute) can be grouped altogether to reduce the number of condition checks, thereby further simplifying the scheme. FIG. 8 illustrates an exemplary hierarchy of parameter sets of G-PCC, according to some embodiments of the present disclosure. A point cloud may be represented in a 1D array including a set of points each associated with a property, such as geometry and attributes (e.g., color and reflectance). The set of points associated with different time stamps may be viewed as a “sequence.”

As shown in FIG. 8, the syntax elements (e.g., parameters, flags, etc.) used for coding the headers of the point cloud may be organized in a hierarchy having various levels. At the top level, the hierarchy may include a sequence header, for example, a header of a sequence parameter set (SPS) associated with the sequence representing the point cloud. At the second level, the hierarchy may include one or more property headers belonging to the sequence header, such as a geometry parameter header and one or more attribute parameter headers. In some embodiments, geometry parameter headers, and attribute parameter headers can also be at the same level as SPS. For example, as shown in FIG. 8, the next level under the SPS may include one header of a geometry parameter set belonging to the SPS and associated with the geometry, as well as one or more headers (1 to n) of attribute parameter sets belonging to the SPS and each associate with a respective attribute (e.g., color or reflectance). At the third level, the hierarchy may include one or more slice property headers belonging to each property header, such as slice geometry parameter headers and slice attribute parameter headers. That is, the sequence representing the point cloud may be divided into one or more slices each including a slice of points, and each slice of points may be associated with one or more slice property headers. For example, as shown in FIG. 8, the next level under the geometry parameter set may include one or more headers of slice geometry parameter sets each belonging to the geometry parameter set and associated with a respective slice of points. Similarly, the next level under each attribute parameter set may include one or more headers of slice attribute parameter sets each belonging to the respective attribute parameter set and associated with a respective slice of points. It is understood that in some examples, the hierarchy may include fewer or more levels, such as picture/frame level(s).

According to some aspects of the present disclosure, the difference in attribute values between the current point and its predictor may be referred to as a “residual.” Depending on the application, PCC can be either lossless or lossy. Hence, the residual may or may not be quantized by using the predefined quantization process. According to the present disclosure, the residual without or with quantization may be referred to as a “level,” which is a signed integer (e.g., a positive or negative integer value) coded into the bitstream.

To reduce bitstream overhead, the maximum number of attributes (e.g., color, reflectance, depth, etc.) may be indicated as the maximum number of attributes minus 1. To that end, a maxNumAttributesMinus1 syntax element may be coded into the bitstream. According to some aspects consistent with the present disclosure, decoder 201 may infer the value of the maxNumAttributesMinus1 syntax element is equal to −1. Moreover, the present disclosure moves the colorQuantParam and reflQuantParam syntax elements from the SPS header to the attribute header, as illustrated below in Table 5.

TABLE 5
Exemplary changes to the SPS header
sequence_header( ) {   Descriptor
profile_id             u(8)
level_id               u(8)
.......
attribute_present_flag
if (attribute_present_flag) {
attribute_adapt_pred   u(1)
maxNumAttributesMinus1 u(4)
}
byte_alignment( )
}

TABLE 6
Exemplary changes to the attribute header
attribute_header( ) { Descriptor
for    ( attrIdx   =   0; attrIdx <
(maxNumAttributesMinus1 + 1); attrIdx ++ ){
..............
if (attrIdx == 0) {
....
colorReorderMode      ue(v)
colorGolombNum        ue(v)
colorQuantParam       ue(v)
}
if (attrIdx == 1) {
.......
refReorderMode        ue(v)
refGolombNum          ue(v)
reflQuantParam        ue(v)
}
}
}
.......
}
byte_alignment( )
}

Referring to Table 6, the maxNumAttributesMinus1 plus 1 syntax element may indicate the maximum number of supported attributes. The value of maxNumAttributesMinus1 may be in the range of 0 to 15, inclusive. When not present in the bitstream, decoder 201 may infer the value of maxNumAttributesMinus1 as equal to −1.

In the current AVS-GPCC specification, MPEG-GPCC specification, etc., each attribute only supports a single parameter set. For example, a point cloud may be associated with a single set of color data (e.g., a first attribute), a single set of reflectance data (e.g., a second attribute), a single set of distance data (e.g., a third attribute) and so on. However, there are scenarios in which supporting multiple parameter sets may be beneficial. These scenarios include, without limitation, a point cloud associated with a painting that has faded. For instance, a compressed point cloud of a renaissance painting may be associated with a first parameter set associated with the colors used when the painting was originally made, and a second parameter set associated with the present colors (which have faded since it was originally made).

Hence, enabling multiple attribute coding parameter sets for one type of attribute may be desirable. To support a wider range of GPCC applications, the present disclosure enables multiple attribute coding parameter sets for one type of attribute, as shown below in Tables 7-9.

TABLE 7
Exemplary SPS header to support multiple attribute coding parameter sets
sequence_header( ) {    Descriptor
profile_id              u(8)
level_id                u(8)
......
attribute_present_flag
if (attribute_present_flag) {
attribute_adapt_pred    u(1)
sps_multi_data_set_flag u(1)
maxNumAttributesMinus1  u(4)
}
byte_alignment( )
}

TABLE 8
Exemplary attribute header to support multiple attribute coding parameter sets
attribute_header( ) {            Descriptor
for   ( attrIdx   =   0; attrIdx < (max NumAttributesMinus1   +
1); attrIdx ++ ){
attributePresentFlag [ attrIdx ] u(1)
if(attributePresentFlag [ attrIdx ]){
if(sps_multi_data_set_flag)
multi_data_set_flag              u(1)
if(multi_data_set_flag)
attribute_num_data_set_minus1[attrIdx] ue(v)
for(i=0;i<     (attribute_num_data_set_minus1[attrIdx]+1);
i++){
outputBitDepthMinus1[ attrIdx ]  ue(v)
if (attrIdx == 0 || attrIdx == 1) {
maxNumOfNeighboursLog2Minus7[ attrIdx ] u(2)
numOflevelOfDetail[ attrIdx ]    ue(v)
maxNumOfPredictNeighbours[ attrIdx ] ue(v)
intraLodFlag[ attrIdx ]          u(1)
crossAttrTypePred                u(1)
if (crossAttrTypePred){
attrEncodeOrder                  u(1)
crossAttrTypePredParam1          u(15)
crossAttrTypePredParam2          u(21)
}
}
if (attrIdx == 0) {
cross_component_Pred             u(1)
orderSwitch                      u(1)
half_zero_runlength_enable       u(1)
chroma QpOffsetCb                se(v)
chromaQpOffsetCr                 se(v)
colorReorderMode                 ue(v)
colorGolombNum                   ue(v)
}
if (attrIdx == 1) {
nearestPredParam1                ue(v)
nearestPredParam2                ue(v)
axisBias                         ue(v)
refReorderMode                   ue(v)
refGolombNum                     ue(v)
}
transform                        ue(v)
if (transform && attributePresentFlag [ attrIdx ]
maxNumofCoeff                    ue(v)
coeffLengthControl               ue(v)
attrTransformQpDelta             ue(v)
initPredTransRatio               se(v)
transResLayer                    u(1)
attrTransformNumPoints           ue(v)
maxTransNum                      ue(v)
QpOffsetDC                       se(v)
QpOffsetAC                       se(v)
if ( attributePresentFlag[0]) {
chromaQpOffsetDC                 se(v)
chromaQpOffsetAC                 se(v)
}
if ( attributePresentFlag[1]) {
RefGroupPred                     u(1)
}
} //if (transform && ( attributePresentFlag[idx]
} // for(i=0;i< Num
} // if(attributePresentFlag [ attrIdx ]){
} // for ( attrIdx = 0; attrIdx < (maxNumAttributesMinus1
byte_alignment( )
}

TABLE 9
Exemplary attribute present flag to support multiple attribute coding
parameter sets
general_attribute_data_bitstream( ) { Descriptor
if (attributePresentFlag[1]) {
for(i=0;i< (attribute_num_data_set_minus1[1] +1); i++){
attribute_data_reflectance( )
byte_alignment( )
}
}
if (attributePresentFlag[0]) {
for(i=0;i< (attribute_num_data_set_minus1[0]+1); i++){
attribute_data_color( )
byte_alignment( )
}
}
}

Referring to Table 7, an sps_multi_data_set_flag may be used to indicate whether the bitstream includes multiple attribute coding parameter sets. For example, encoder 101 may generate an sps_multi_data_set_flag value (e.g., a first syntax element) equal to 1, which may indicate that multiple attribute coding parameter sets are enabled for the current point cloud. On the other hand, an sps_multi_data_set_flag value equal to 0 specifies that multiple attribute coding parameter sets are not enabled for the point cloud. When not present in the bitstream, decoder 201 may infer that the value of the sps_multi_data_set_flag is equal to 0.

Referring to Table 8, a multi_data_set_flag[attrIdx] value equal to 1 may indicate that multiple attribute parameter sets are enabled for the current type of attribute, and the number of allowed attribute coding parameter sets will be further specified by the attribute_num_data_set_minus1 syntax element. On the other hand, a multi_data_set_flag value equal to 0 specifies that multiple attribute parameter sets are not enabled for the current type of attribute, and the number of allowed attribute coding parameter sets is equal to 1. When not present in the bitstream, decoder 201 may infer that the value of the multi_data_set_flag is equal to 0. In some embodiments, the multi_data_set_flag may be indicated as a multi_data_set_flag[attrIdx], where the [attrIdx] is associated with the attribute index correlated to the attribute to which the multi_data_set_flag refers. By way of example and not limitation, assume the attribute associated with the multi_data_set_flag is the “color attribute” with an index value of 0, the second syntax element coded into the bitstream may include multi_data_set_flag[0].

Referring to Table 8, the attribute_num_data_set_minus1[attrIdx] syntax element plus 1 may indicate the number of parameter sets for coding the current attribute. The current attribute may be indicated by the address index (attrIdx). For instance, an attribute index of 1 may indicate a color attribute, an attribute index of 2 may indicate a reflectance attribute, an attribute index of 3 may indicate a depth attribute, and so on. The value of attribute_num_data_set_minus1 may be in the range of 0 to 15, inclusive. When not present in the bitstream, decoder 201 may infer that the value of attribute_num_data_set_minus1 is equal to 0.

The number of allowed attribute coding parameter sets (also referred to herein as “parameter sets”) may be calculated according to expression (6).

$\begin{array}{cc}\mathrm{num\_allowed}\mathrm{\_attribute}\mathrm{\_coding}=\mathrm{attribute\_num}\mathrm{\_data}\mathrm{\_set}\mathrm{\_minus1}+1.& \left(6\right)\end{array}$

When all attributes may use the same transform-related syntax, alternative tables may be specified, as illustrated in Tables 10-12.

TABLE 10
Exemplary SPS header to support multiple attribute coding parameter sets
sequence_header( ) {    Descriptor
profile_id              u(8)
level_id                u(8)
......
attribute_present_flag
if (attribute_present_flag) {
attribute_adapt_pred    u(1)
sps_multi_data_set_flag u(1)
maxNumAttributesMinus1  u(4)
}
byte_alignment( )
}

TABLE 11
Exemplary attribute header to support multiple attribute coding parameter sets
attribute_header( ) {            Descriptor
for   ( attrIdx   =   0; attrIdx < (maxNumAttributesMinus1   +
1); attrIdx ++ ){
attributePresentFlag [ attrIdx ] u(1)
if(attributePresentFlag [ attrIdx ]){
if(sps_multi_data_set_flag)
multi_data_set_flag              u(1)
if(multi_data_set_flag)
attribute_num_data_set_minus1[attrIdx] ue(v)
for(i=0;i<     (attribute_num_data_set_minus1[attrIdx]+1);
i++){
outputBitDepthMinus1[ attrIdx ]  ue(v)
if (attrIdx == 0) || attrIdx == 1) {
maxNumOfNeighboursLog2Minus7[ attrIdx ] u(2)
numOflevelOfDetail[ attrIdx ]    ue(v)
maxNumOfPredictNeighbours[ attrIdx ] ue(v)
intraLodFlag[ attrIdx ]          u(1)
crossAttrTypePred                u(1)
if (crossAttrTypePred){
attrEncodeOrder                  u(1)
crossAttrTypePredParam1          u(15)
crossAttrTypePredParam2          u(21)
}
}
if (attrIdx == 0) {
cross_component_Pred             u(1)
orderSwitch                      u(1)
half_zero_runlength_enable       u(1)
chromaQpOffsetCb                 se(v)
chromaQpOffsetCr                 se(v)
colorReorderMode                 ue(v)
colorGolombNum                   ue(v)
}
if (attrIdx == 1) {
nearestPredParam1                ue(v)
nearestPredParam2                ue(v)
axisBias                         ue(v)
refReorderMode                   ue(v)
refGolombNum                     ue(v)
}
} // for(i=0;i< Num
} // if(attributePresentFlag [ attrIdx ]){
} // for ( attrIdx = 0; attrIdx < (maxNumAttributesMinus1
transform                        ue(v+)
if                    (transform                      &&
( attributePresentFlag[0] || attributePresentFlag[1]) ) {
maxNumofCoeff                    ue(v)
coeffLengthControl               ue(v)
attrTransformQpDelta             ue(v)
initPredTransRatio               se(v)
transResLayer                    u(1)
attrTransformNumPoints           ue(v)
maxTransNum                      ue(v)
QpOffsetDC                       se(v)
QpOffsetAC                       se(v)
if ( attributePresentFlag[0]) {
chromaQpOffsetDC                 se(v)
chromaQpOffsetAC                 se(v)
}
if ( attributePresentFlag[1]) {
RefGroupPred                     u(1)
}
} //if (transform && ( attributePresentFlag[idx]
byte_alignment( )
}

TABLE 12
Exemplary attribute present flag to support multiple attribute coding
parameter sets
general_attribute_data_bitstream( ) { Descriptor
if (attributePresentFlag[1]) {
for(i=0;i< (attribute_num_data_set_minus1[1] +1); i++){
attribute_data_reflectance( )
byte_alignment( )
}
}
if (attributePresentFlag[0]) {
For(i=0;i< (attribute_num_data_set_minus1[0]+1); i++){
attribute_data_color( )
byte_alignment( )
}
}
}

FIG. 9 illustrates a flow chart of an exemplary method 900 of point cloud encoding, according to some embodiments of the present disclosure. Method 900 may be performed by encoder 101 of encoding system 100 or any other suitable point cloud encoding systems. Method 900 may include operations 902-918, as described below. It is understood that some of the operations may be optional, and some of the operations may be performed simultaneously, or in a different order than shown in FIG. 9.

At 902, the encoder may generate a first syntax element indicative of multiple attribute parameter sets for the point cloud. For example, encoder 101 may generate an sps_multi_data_set_flag value (e.g., a first syntax element) equal to 1 may indicate that multiple attribute coding parameter sets are enabled for the current point cloud. On the other hand, an sps_multi_data_set_flag value equal to 0 specifies that multiple attribute coding parameter sets are not enabled for the current type of attribute. When not present in the bitstream, encoder 101 may infer that the value of the sps_multi_data_set_flag is equal to 0.

At 904, the encoder may input the first syntax element into a bitstream. For example, encoder 101 may input the sps_multi_data_set_flag into the bitstream.

At 906, the encoder may, in response to the first syntax element indicating that the multiple attribute parameter sets are enabled for the point cloud, generate a second syntax element indicative of multiple parameter sets for an attribute. For example, encoder 101 may generate a multi_data_set_flag (e.g., a second syntax element) to indicate whether an attribute has multiple parameter sets. Different multi_data_set_flag syntax elements may be generated for different attributes. For instance, a first multi_data_set flag may be generated to indicate whether the color attribute has multiple parameter sets, a second multi_data_flag may be generated to indicate whether the reflectance attribute has multiple parameter sets, a third multi_data_flag may be generated to indicate whether the depth attribute has multiple parameter sets, and so on. In some embodiments, a multi_data_set_flag value equal to 1 may indicate that multiple attribute parameter sets are enabled for the current type of attribute. On the other hand, a multi_data_set_flag value equal to 0 specifies that multiple attribute coding parameter sets are not enabled for the current type of attribute. When not present in the bitstream, decoder 201 may infer that the value of the multi_data_set_flag is equal to 0.

At 908, the encoder may input the second syntax element indicative of multiple parameter sets for the attribute into the bitstream. For example, encoder 101 may input the multi_data_set flag into the bitstream.

At 910, the encoder may, in response to the second syntax element indicating the attribute has multiple parameter sets, generate a third syntax element indicative of a number of parameter sets associated with the attribute. For example, encoder 101 may generate, for each type of attribute, an attribute_num_data_set_minus1 syntax element (e.g., a third syntax element) to indicate the number of parameter sets associated with a type of attribute. For instance, a first attribute_num_data_set_minus1 syntax element may be generated to indicate the number of parameter sets associated with the color attribute, a second attribute_num_data_set_minus1 syntax element may be generated to indicate the number of parameter sets associated with the reflectance attribute, a third attribute_num_data_set_minus1 syntax element may be generated to indicate the number of parameter sets associated with the depth attribute, and so on. The attribute_num_data_set_minus1[attrIdx] syntax element (e.g., a third syntax element) plus 1 may indicate the number of parameter sets for coding the current attribute. The current attribute may be indicated by the address index (attrIdx). For instance, an attribute index of 1 may indicate a color attribute, an attribute index of 2 may indicate a reflectance attribute, an attribute index of 3 may indicate a depth attribute, and so on. The value of attribute_num_data_set_minus1 may be in the range of 0 to 15, inclusive. When not present in the bitstream, encoder 101 may infer that the value of attribute_num_data_set_minus1 is equal to 0.

At 912, the encoder may input the third syntax element indicative of the number of parameter sets associated with the attribute into the bitstream. For example, encoder 101 may input the attribute_num_data_set_minus1 syntax element into the bitstream.

At 914, the encoder may, in response to the second syntax element indicating the attribute does not have multiple parameter sets, omit a generation of the third syntax element. For example, encoder 101 may not generate the attribute_num_data_set_minus1 syntax element.

At 916, the encoder may, in response to the multiple attribute parameter sets being enabled for the point cloud, compress the point cloud based on the multiple attribute parameter sets. For example, encoder 101 may compress and/or encode the point cloud by using multiple attribute parameter sets when an attribute has more than one parameter set associated therewith. For instance, encoder 101 may encode the point cloud with two or more color parameter sets. Encoder 101 may encode the point cloud with two or more reflectance parameter sets. Encoder 101 may encode the point cloud with two or more depth parameter sets.

At 918, the encoder may, in response to the multiple attribute parameter sets not being enabled for the point cloud, compress the point cloud based on a single attribute parameter set. For example, encoder 101 may compress and/or encode the point cloud by using a single attribute parameter set when each of the attributes is associated with a single parameter set.

FIG. 10 illustrates a flow chart of an exemplary method 1000 of point cloud decoding, according to some embodiments of the present disclosure. Method 1000 may be performed by decoder 201 of decoding system 200 or any other suitable point cloud encoding systems. Method 1000 may include operations 1002-1016 as described below. It is understood that some of the operations may be optional, and some of the operations may be performed simultaneously, or in a different order than shown in FIG. 10.

At 1002, the decoder may parse a bitstream to obtain a first syntax element indicative of an enablement of multiple attribute parameter sets for the point cloud. For example, decoder 201 may parse a bitstream to obtain an sps_multi_data_set flag (e.g., a first syntax element).

At 1004, the decoder may determine whether the first syntax element indicates that multiple attribute parameter sets are enabled for the point cloud. For example, decoder 201 may determine whether the multiple attribute parameter sets are enabled based on a value of the sps_multi_data_set_flag. An sps_multi_data_set_flag value equal to 1 may indicate that multiple attribute parameter sets are enabled for the current point cloud. On the other hand, an sps_multi_data_set_flag value equal to 0 specifies that multiple attribute parameter sets are not enabled for the current point cloud.

At 1006, the decoder may, in response to the first syntax element indicating that the multiple attribute parameter sets are enabled for the point cloud, parse the bitstream to obtain a second syntax element indicative of multiple parameter sets for an attribute. For example, when the sps_multi_data_set_flag is set to 1, decoder 201 may further parse the bitstream to obtain a multi_data_set_flag (e.g., a second syntax element).

At 1008, the decoder may determine whether the second syntax element indicates the attribute has multiple parameter sets. For example, based on a value of the multi_data_set_flag, decoder 201 may determine whether an attribute has multiple parameter sets. Different multi_data_set_flag syntax elements may be included in the bitstream for different attributes. For instance, a first multi_data_set flag may indicate whether the color attribute has multiple parameter sets, a second multi_data_flag may indicate whether the reflectance attribute has multiple parameter sets, a third multi_data_flag may indicate whether the depth attribute has multiple parameter sets, and so on. In some embodiments, a multi_data_set_flag value equal to 1 may indicate that multiple attribute coding parameter sets are enabled for the current type of attribute. On the other hand, a multi_data_set_flag value equal to 0 specifies that multiple attribute parameter sets are not enabled for the current type of attribute. When not present in the bitstream, decoder 201 may infer that the value of the multi_data_set_flag is equal to 0.

At 1010, the decoder may, in response to the second syntax element indicating the attribute has multiple parameter sets, parse the bitstream to obtain a third syntax element indicative of a number of parameter sets associated with the attribute. For example, decoder 201 may parse the bitstream to obtain an attribute_num_data_set_minus1 syntax element (e.g., a third syntax element) for each type of attribute.

At 1012, the decoder may identify the number of parameter sets associated with the attribute based on the third syntax element. For example, the attribute_num_data_set_minus1[attrIdx] syntax element (e.g., a third syntax element) plus 1 may indicate the number of parameter sets for coding the current attribute. The current attribute may be indicated by the address index (attrIdx). For instance, an attribute index of 1 may indicate a color attribute, an attribute index of 2 may indicate a reflectance attribute, an attribute index of 3 may indicate a depth attribute, and so on. The value of attribute_num_data_set_minus1 may be in the range of 0 to 15, inclusive. When not present in the bitstream, decoder 201 may infer that the value of attribute_num_data_set_minus1 is equal to 0. Decoder 201 may identify the number of allowed attribute parameter sets (also referred to herein as “parameter sets”) using the calculation associated with expression (6).

At 1014, the decoder may, in response to the second syntax element indicating the attribute does not have multiple parameter sets, determine the attribute has a single parameter set associated therewith. For example, decoder 201 may parse the second syntax element from the bitstream. Based on the receipt of the second syntax element, decoder 201 may determine that the associated attribute (e.g., color, reflectance, intensity, etc.) has a single parameter set associated therewith.

At 1016, the decoder may, in response to determining that the multiple attribute parameter sets are enabled for the point cloud, decompress the point cloud based on the multiple attribute parameter sets. For example, decoder 201 may decompress and/or decode the point cloud from the bitstream based on the multiple attribute parameter sets when present.

At 1018, the decoder may, in response to determining that the multiple attribute parameter sets are not enabled for the point cloud, decompress the point cloud based on a single attribute parameter set. For example, decoder 201 may decompress and/or decode the point cloud from the bitstream based on a single attribute parameter set when each attribute type has only a single parameter set associated therewith.

In various aspects of the present disclosure, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as instructions on a non-transitory computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a processor, such as processor 102 in FIGS. 1 and 2. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, HDD, such as magnetic disk storage or other magnetic storage devices, Flash drive, SSD, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a processing system, such as a mobile device or a computer. Disk and disc, as used herein, includes CD, laser disc, optical disc, digital video disc (DVD), and floppy disk where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

According to one aspect of the present disclosure, a method for decoding a point cloud that is represented in a 1D array that includes a set of points is provided. The method may include parsing, by at least one processor, a bitstream to obtain a first syntax element indicative of an enablement of multiple attribute parameter sets for the point cloud. The method may include determining, by the at least one processor, whether the first syntax element indicates that multiple attribute parameter sets are enabled for the point cloud. In response to determining that the multiple attribute parameter sets are enabled for the point cloud, the method may include decompressing, by the at least one processor, the point cloud based on the multiple attribute parameter sets.

In some embodiments, in response to determining that the multiple attribute parameter sets are not enabled for the point cloud, the method may include decompressing, by the at least one processor, the point cloud based on a single attribute parameter set.

In some embodiments, in response to the first syntax element indicating that the multiple attribute parameter sets are enabled for the point cloud, the method may include parsing, by the at least one processor, the bitstream to obtain a second syntax element indicative of multiple parameter sets for an attribute. In some embodiments, the method may include determining, by the at least one processor, whether the second syntax element indicates the attribute has multiple parameter sets.

In some embodiments, in response to the second syntax element indicating the attribute has multiple parameter sets, the method may include parsing, by the at least one processor, the bitstream to obtain a third syntax element indicative of a number of parameter sets associated with the attribute. In some embodiments, the method may include identifying, by the at least one processor, the number of parameter sets associated with the attribute based on the third syntax element.

In some embodiments, in response to the second syntax element indicating the attribute does not have multiple parameter sets, the method may include determining, by the at least one processor, the attribute has a single parameter set associated therewith.

In some embodiments, the first syntax element may include an sps_multi_data_set flag. In some embodiments, the second syntax element may include a multi_data_set flag. In some embodiments, the third syntax element may include an attribute_num_data_set_minus1[attrIdx] syntax element. In some embodiments, the value of the attribute_num_data_set_minus1[attrIdx] syntax element coded in the bitstream may be indicative of the number of allowed multiple attribute parameter sets for the attribute which is sum of the attribute_num_data_set_minus1[attrIdx] and 1.

According to another aspect of the present disclosure, a system for decoding a point cloud that is represented in a 1D array that includes a set of points is provided. The system may include at least one processor and memory storing instructions. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to parse a bitstream to obtain a first syntax element indicative of an enablement of multiple attribute parameter sets for the point cloud. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to determine whether the first syntax element indicates that multiple attribute parameter sets are enabled for the point cloud. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to, in response to determining that the multiple attribute parameter sets are enabled for the point cloud, decompress the point cloud based on the multiple attribute parameter sets.

In some embodiments, the memory storing instructions, which when executed by the at least one processor, may further cause the at least one processor to, in response to determining that the multiple attribute parameter sets are not enabled for the point cloud, decompress the point cloud based on a single attribute parameter set.

In some embodiments, the memory storing instructions, which when executed by the at least one processor, may further cause the at least one processor to, in response to the first syntax element indicating that the multiple attribute parameter sets are enabled for the point cloud, parse the bitstream to obtain a second syntax element indicative of multiple parameter sets for an attribute. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to determine whether the second syntax element indicates the attribute has multiple parameter sets.

In some embodiments, the memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to, in response to the second syntax element indicating the attribute has multiple parameter sets, parse the bitstream to obtain a third syntax element indicative of a number of parameter sets associated with the attribute. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to identify the number of parameter sets associated with the attribute based on the third syntax element.

In some embodiments, in response to the second syntax element indicating the attribute does not have multiple parameter sets, the memory storing instructions, which when executed by the at least one processor may cause the at least one processor to determine the attribute has a single parameter set associated therewith.

In some embodiments, the first syntax element may include an sps_multi_data_set flag. In some embodiments, the second syntax element may include a multi_data_set_flag. In some embodiments, the third syntax element may include an attribute_num_data_set_minus1[attrIdx] syntax element. In some embodiments, the value of the attribute_num_data_set_minus1[attrIdx] syntax element coded in the bitstream may be indicative of the number of allowed multiple attribute parameter sets for the attribute which is sum of the attribute_num_data_set_minus1[attrIdx] and 1.

According to a further aspect of the present disclosure, a method for encoding a point cloud that is represented in a 1D array that includes a set of points is provided. The method may include generating, by at least one processor, a first syntax element indicative of multiple attribute parameter sets for the point cloud. The method may include inputting, by the at least one processor, the first syntax element into a bitstream. In response to the multiple attribute parameter sets being enabled for the point cloud, the method may include compressing, by the at least one processor, the point cloud based on the multiple attribute parameter sets.

In some embodiments, in response to the multiple attribute parameter sets not being enabled for the point cloud, the method may include compressing, by the at least one processor, the point cloud based on a single attribute parameter set.

In some embodiments, in response to the first syntax element indicating that the multiple attribute parameter sets are enabled for the point cloud, the method may include generating, by the at least one processor, a second syntax element indicative of multiple parameter sets for an attribute. In some embodiments, the method may include inputting, by the at least one processor, the second syntax element indicative of multiple parameter sets for the attribute into the bitstream.

In some embodiments, in response to the second syntax element indicating the attribute has multiple parameter sets, the method may include generating, by the at least one processor, a third syntax element indicative of a number of parameter sets associated with the attribute. In some embodiments, inputting, by the at least one processor, the third syntax element indicative of the number of parameter sets associated with the attribute into the bitstream.

In some embodiments, in response to the second syntax element indicating the attribute does not have multiple parameter sets, the method may include omitting, by the at least one processor, a generation of the third syntax element.

In some embodiments, the first syntax element may include an sps_multi_data_set flag. In some embodiments, the second syntax element may include a multi_data_set flag. In some embodiments, the third syntax element may include an attribute_num_data_set_minus1[attrIdx] syntax element. In some embodiments, the value of the attribute_num_data_set_minus1[attrIdx] syntax element coded in the bitstream may be indicative of the number of allowed multiple attribute parameter sets for the attribute which is sum of the attribute_num_data_set_minus1[attrIdx] and 1.

According to a further aspect of the present disclosure, a system for encoding a point cloud that is represented in a 1D array that includes a set of points is provided. The system may include at least one processor and memory storing instructions. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to generate a first syntax element indicative of multiple attribute parameter sets for the point cloud. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to input the first syntax element into a bitstream. The memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to, in response to the multiple attribute parameter sets being enabled for the point cloud, compressing the point cloud based on the multiple attribute parameter sets.

In some embodiments, the memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to, in response to the multiple attribute parameter sets not being enabled for the point cloud, compress the point cloud based on a single attribute parameter set.

In some embodiments, the memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to, in response to the first syntax element indicating that the multiple attribute parameter sets are enabled for the point cloud, generate a second syntax element indicative of multiple parameter sets for an attribute. In some embodiments, the memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to input the second syntax element indicative of multiple parameter sets for the attribute into the bitstream.

In some embodiments, the memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to, in response to the second syntax element indicating the attribute has multiple parameter sets, generate a third syntax element indicative of a number of parameter sets associated with the attribute. In some embodiments, the memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to input the third syntax element indicative of the number of parameter sets associated with the attribute into the bitstream.

In some embodiments, in response to the second syntax element indicating the attribute does not have multiple parameter sets, the memory storing instructions, which when executed by the at least one processor, may cause the at least one processor to omit a generation of the third syntax element.

In some embodiments, the first syntax element may include an sps_multi_data_set flag. In some embodiments, the second syntax element may include a multi_data_set flag. In some embodiments, the third syntax element may include an attribute_num_data_set_minus1[attrIdx] syntax element. In some embodiments, the value of the attribute_num_data_set_minus1[attrIdx] syntax element coded in the bitstream may be indicative of the number of allowed multiple attribute parameter sets for the attribute which is sum of the attribute_num_data_set_minus1[attrIdx] and 1.

The foregoing description of the embodiments will so reveal the general nature of the present disclosure that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

Embodiments of the present disclosure have been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way.

Various functional blocks, modules, and steps are disclosed above. The arrangements provided are illustrative and without limitation. Accordingly, the functional blocks, modules, and steps may be reordered or combined in different ways than in the examples provided above. Likewise, some embodiments include only a subset of the functional blocks, modules, and steps, and any such subset is permitted.

The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. A method for decoding a point cloud, the point cloud being represented in a one-dimension (1D) array comprising a set of points, the method comprising: parsing, by at least one processor, a bitstream to obtain a first syntax element indicative of an enablement of multiple attribute parameter sets for the point cloud;determining, by the at least one processor, whether the first syntax element indicates that multiple attribute parameter sets are enabled for the point cloud; andin response to determining that the multiple attribute parameter sets are enabled for the point cloud, decompressing, by the at least one processor, the point cloud based on the multiple attribute parameter sets.

2. The method of claim 1, further comprising: in response to determining that the multiple attribute parameter sets are not enabled for the point cloud, decompressing, by the at least one processor, the point cloud based on a single attribute parameter set.

3. The method of claim 1, further comprising: in response to the first syntax element indicating that the multiple attribute parameter sets are enabled for the point cloud, parsing, by the at least one processor, the bitstream to obtain a second syntax element indicative of multiple parameter sets for an attribute; anddetermining, by the at least one processor, whether the second syntax element indicates the attribute has multiple parameter sets.

4. The method of claim 3, further comprising: in response to the second syntax element indicating the attribute has multiple parameter sets, parsing, by the at least one processor, the bitstream to obtain a third syntax element indicative of a number of parameter sets associated with the attribute; andidentifying, by the at least one processor, the number of parameter sets associated with the attribute based on the third syntax element.

5. The method of claim 4, further comprising: in response to the second syntax element indicating the attribute does not have multiple parameter sets, determining, by the at least one processor, the attribute has a single parameter set associated therewith.

6. The method of claim 4, wherein: the first syntax element includes an sps_multi_data_set_flag,the second syntax element includes a multi_data_set_flag,the third syntax element includes an attribute_num_data_set_minus1[attrIdx] syntax element, andthe value of the attribute_num_data_set_minus1[attrIdx] syntax element plus 1 coded in the bitstream is indicative of the number of allowed multiple attribute parameter sets for the attribute.

7. A system for decoding a point cloud, the point cloud being represented in a one-dimension (1D) array comprising a set of points, the system comprising: at least one processor; andmemory storing instructions, which when executed by the at least one processor, cause the at least one processor to: parse a bitstream to obtain a first syntax element indicative of an enablement of multiple attribute parameter sets for the point cloud;determine whether the first syntax element indicates that multiple attribute parameter sets are enabled for the point cloud; andin response to determining that the multiple attribute parameter sets are enabled for the point cloud, decompress the point cloud based on the multiple attribute parameter sets.

8. The system of claim 7, wherein the memory storing instructions, which when executed by the at least one processor, further cause the at least one processor to: in response to determining that the multiple attribute parameter sets are not enabled for the point cloud, decompress the point cloud based on a single attribute parameter set.

9. The system of claim 7, wherein the memory storing instructions, which when executed by the at least one processor, further cause the at least one processor to: in response to the first syntax element indicating that the multiple attribute parameter sets are enabled for the point cloud, parse the bitstream to obtain a second syntax element indicative of multiple parameter sets for an attribute; anddetermine whether the second syntax element indicates the attribute has multiple parameter sets.

10. The system of claim 9, wherein the memory storing instructions, which when executed by the at least one processor, further cause the at least one processor to: in response to the second syntax element indicating the attribute has multiple parameter sets, parse the bitstream to obtain a third syntax element indicative of a number of parameter sets associated with the attribute; andidentify the number of parameter sets associated with the attribute based on the third syntax element.

11. The system of claim 10, wherein the memory storing instructions, which when executed by the at least one processor, further cause the at least one processor to: in response to the second syntax element indicating the attribute does not have multiple parameter sets, determine the attribute has a single parameter set associated therewith.

12. The system of claim 10, wherein: the first syntax element includes an sps_multi_data_set_flag,the second syntax element includes a multi_data_set_flag, andthe third syntax element includes an attribute_num_data_set_minus1[attrIdx] syntax element, andthe value of the attribute_num_data_set_minus1[attrIdx] syntax element coded in the bitstream is indicative of the number of allowed multiple attribute parameter sets for the attribute which is sum of the attribute_num_data_set_minus1[attrIdx] and 1.

13. A method for encoding a point cloud, the point cloud being represented in a one-dimension (1D) array comprising a set of points, the method comprising: generating, by at least one processor, a first syntax element indicative of multiple attribute parameter sets for the point cloud;inputting, by the at least one processor, the first syntax element into a bitstream; andin response to the multiple attribute parameter sets being enabled for the point cloud, compressing, by the at least one processor, the point cloud based on the multiple attribute parameter sets.

14. The method of claim 13, further comprising: in response to the multiple attribute parameter sets not being enabled for the point cloud, compressing, by the at least one processor, the point cloud based on a single attribute parameter set.

15. The method of claim 13, further comprising: in response to the first syntax element indicating that the multiple attribute parameter sets are enabled for the point cloud, generating, by the at least one processor, a second syntax element indicative of multiple parameter sets for an attribute; andinputting, by the at least one processor, the second syntax element indicative of multiple parameter sets for the attribute into the bitstream.

16. The method of claim 15, further comprising: in response to the second syntax element indicating the attribute has multiple parameter sets, generating, by the at least one processor, a third syntax element indicative of a number of parameter sets associated with the attribute; andinputting, by the at least one processor, the third syntax element indicative of the number of parameter sets associated with the attribute into the bitstream.

17. The method of claim 16, further comprising: in response to the second syntax element indicating the attribute does not have multiple parameter sets, omitting, by the at least one processor, a generation of the third syntax element.

18. The method of claim 16, wherein: the first syntax element includes an sps_multi_data_set_flag,the second syntax element includes a multi_data_set_flag, andthe third syntax element includes an attribute_num_data_set_minus1[attrIdx] syntax element, andthe value of the attribute_num_data_set_minus1[attrIdx] syntax element coded in the bitstream is indicative of the number of allowed multiple attribute parameter sets for the attribute which is sum of the attribute_num_data_set_minus1[attrIdx] and 1.

19.-25. (canceled)