Patent Application
20240420377
Embodiments relate to a method and device for processing point cloud content.
Point cloud content is content represented by a point cloud, which is a set of points belonging to a coordinate system representing a three-dimensional space. The point cloud content may express media configured in three dimensions, and is used to provide various services such as virtual reality (VR), augmented reality (AR), mixed reality (MR), and self-driving services. However, tens of thousands to hundreds of thousands of point data are required to represent point cloud content. Therefore, there is a need for a method for efficiently processing a large amount of point data.
Embodiments provide a device and method for efficiently processing point cloud data. Embodiments provide a point cloud data processing method and device for addressing latency and encoding/decoding complexity.
The technical scope of the embodiments is not limited to the aforementioned technical objects, and may be extended to other technical objects that may be inferred by those skilled in the art based on the entire contents disclosed herein.
To achieve these objects and other advantages and in accordance with the purpose of the disclosure, as embodied and broadly described herein, a method of transmitting point cloud data may include encoding point cloud data, and transmitting a bitstream containing the point cloud data. In another aspect of the present disclosure, a method of receiving point cloud data may include receiving a bitstream containing point cloud data, and decoding the point cloud data.
Devices and methods according to embodiments may process point cloud data with high efficiency.
The devices and methods according to the embodiments may provide a high-quality point cloud service.
The devices and methods according to the embodiments may provide point cloud content for providing general-purpose services such as a VR service and a self-driving service.
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the principle of the disclosure. For a better understanding of various embodiments described below, reference should be made to the description of the following embodiments in connection with the accompanying drawings. The same reference numbers will be used throughout the drawings to refer to the same or like parts. In the drawings:
Reference will now be made in detail to the preferred embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present disclosure, rather than to show the only embodiments that may be implemented according to the present disclosure. The following detailed description includes specific details in order to provide a thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that the present disclosure may be practiced without such specific details.
Although most terms used in the present disclosure have been selected from general ones widely used in the art, some terms have been arbitrarily selected by the applicant and their meanings are explained in detail in the following description as needed. Thus, the present disclosure should be understood based upon the intended meanings of the terms rather than their simple names or meanings.
The point cloud content providing system illustrated in
The point cloud data transmission device 10000 according to the embodiments may secure and process point cloud video (or point cloud content) and transmit the same. According to embodiments, the transmission device 10000 may include a fixed station, a base transceiver system (BTS), a network, an artificial intelligence (AI) device and/or system, a robot, an AR/VR/XR device and/or server. According to embodiments, the transmission device 10000 may include a device, a robot, a vehicle, an AR/VR/XR device, a portable device, a home appliance, an Internet of Thing (IoT) device, and an AI device/server which are configured to perform communication with a base station and/or other wireless devices using a radio access technology (e.g., 5G New RAT (NR), Long Term Evolution (LTE)).
The transmission device 10000 according to the embodiments includes a point cloud video acquirer 10001, a point cloud video encoder 10002, and/or a transmitter (or communication module) 10003.
The point cloud video acquirer 10001 according to the embodiments acquires a point cloud video through a processing process such as capture, synthesis, or generation. The point cloud video is point cloud content represented by a point cloud, which is a set of points positioned in a 3D space, and may be referred to as point cloud video data. The point cloud video according to the embodiments may include one or more frames. One frame represents a still image/picture. Therefore, the point cloud video may include a point cloud image/frame/picture, and may be referred to as a point cloud image, frame, or picture.
The point cloud video encoder 10002 according to the embodiments encodes the acquired point cloud video data. The point cloud video encoder 10002 may encode the point cloud video data based on point cloud compression coding. The point cloud compression coding according to the embodiments may include geometry-based point cloud compression (G-PCC) coding and/or video-based point cloud compression (V-PCC) coding or next-generation coding. The point cloud compression coding according to the embodiments is not limited to the above-described embodiment. The point cloud video encoder 10002 may output a bitstream containing the encoded point cloud video data. The bitstream may contain not only the encoded point cloud video data, but also signaling information related to encoding of the point cloud video data.
The transmitter 10003 according to the embodiments transmits the bitstream containing the encoded point cloud video data. The bitstream according to the embodiments is encapsulated in a file or segment (e.g., a streaming segment), and is transmitted over various networks such as a broadcasting network and/or a broadband network. Although not shown in the figure, the transmission device 10000 may include an encapsulator (or an encapsulation module) configured to perform an encapsulation operation. According to embodiments, the encapsulator may be included in the transmitter 10003. According to embodiments, the file or segment may be transmitted to the reception device 10004 over a network, or stored in a digital storage medium (e.g., USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc.). The transmitter 10003 according to the embodiments is capable of wired/wireless communication with the reception device 10004 (or the receiver 10005) over a network of 4G, 5G, 6G, etc. In addition, the transmitter may perform a necessary data processing operation according to the network system (e.g., a 4G, 5G or 6G communication network system). The transmission device 10000 may transmit the encapsulated data in an on-demand manner.
The reception device 10004 according to the embodiments includes a receiver 10005, a point cloud video decoder 10006, and/or a renderer 10007. According to embodiments, the reception device 10004 may include a device, a robot, a vehicle, an AR/VR/XR device, a portable device, a home appliance, an Internet of Things (IoT) device, and an AI device/server which are configured to perform communication with a base station and/or other wireless devices using a radio access technology (e.g., 5G New RAT (NR), Long Term Evolution (LTE)).
The receiver 10005 according to the embodiments receives the bitstream containing the point cloud video data or the file/segment in which the bitstream is encapsulated from the network or storage medium. The receiver 10005 may perform necessary data processing according to the network system (e.g., a communication network system of 4G, 5G, 6G, etc.). The receiver 10005 according to the embodiments may decapsulate the received file/segment and output a bitstream. According to embodiments, the receiver 10005 may include a decapsulator (or a decapsulation module) configured to perform a decapsulation operation. The decapsulator may be implemented as an element (or component) separate from the receiver 10005.
The point cloud video decoder 10006 decodes the bitstream containing the point cloud video data. The point cloud video decoder 10006 may decode the point cloud video data according to the method by which the point cloud video data is encoded (e.g., in a reverse process to the operation of the point cloud video encoder 10002). Accordingly, the point cloud video decoder 10006 may decode the point cloud video data by performing point cloud decompression coding, which is the reverse process to the point cloud compression. The point cloud decompression coding includes G-PCC coding.
The renderer 10007 renders the decoded point cloud video data. The renderer 10007 may output point cloud content by rendering not only the point cloud video data but also audio data. According to embodiments, the renderer 10007 may include a display configured to display the point cloud content. According to embodiments, the display may be implemented as a separate device or component rather than being included in the renderer 10007.
The arrows indicated by dotted lines in the drawing represent a transmission path of feedback information acquired by the reception device 10004. The feedback information is information for reflecting interactivity with a user who consumes the point cloud content, and includes information about the user (e.g., head orientation information, viewport information, and the like). In particular, when the point cloud content is content for a service (e.g., self-driving service, etc.) that requires interaction with the user, the feedback information may be provided to the content transmitting side (e.g., the transmission device 10000) and/or the service provider. According to embodiments, the feedback information may be used in the reception device 10004 as well as the transmission device 10000, or may not be provided.
The head orientation information according to embodiments is information about the user's head position, orientation, angle, motion, and the like. The reception device 10004 according to the embodiments may calculate the viewport information based on the head orientation information. The viewport information may be information about a region of a point cloud video that the user is viewing. A viewpoint is a point through which the user is viewing the point cloud video, and may refer to a center point of the viewport region. That is, the viewport is a region centered on the viewpoint, and the size and shape of the region may be determined by a field of view (FOV). Accordingly, the reception device 10004 may extract the viewport information based on a vertical or horizontal FOV supported by the device in addition to the head orientation information. Also, the reception device 10004 performs gaze analysis or the like to check the way the user consumes a point cloud, a region that the user gazes at in the point cloud video, a gaze time, and the like. According to embodiments, the reception device 10004 may transmit feedback information including the result of the gaze analysis to the transmission device 10000. The feedback information according to the embodiments may be acquired in the rendering and/or display process. The feedback information according to the embodiments may be secured by one or more sensors included in the reception device 10004. According to embodiments, the feedback information may be secured by the renderer 10007 or a separate external element (or device, component, or the like). The dotted lines in
According to embodiments, the transmission device 10000 may be called an encoder, a transmission device, a transmitter, or the like, and the reception device 10004 may be called a decoder, a receiving device, a receiver, or the like.
The point cloud data processed in the point cloud content providing system of
The elements of the point cloud content providing system illustrated in
The block diagram of
The point cloud content providing system according to the embodiments (e.g., the point cloud transmission device 10000 or the point cloud video acquirer 10001) may acquire a point cloud video (20000). The point cloud video is represented by a point cloud belonging to a coordinate system for expressing a 3D space. The point cloud video according to the embodiments may include a Ply (Polygon File format or the Stanford Triangle format) file. When the point cloud video has one or more frames, the acquired point cloud video may include one or more Ply files. The Ply files contain point cloud data, such as point geometry and/or attributes. The geometry includes positions of points. The position of each point may be represented by parameters (e.g., values of the X, Y, and Z axes) representing a three-dimensional coordinate system (e.g., a coordinate system composed of X, Y and Z axes). The attributes include attributes of points (e.g., information about texture, color (in YCbCr or RGB), reflectance r, transparency, etc. of each point). A point has one or more attributes. For example, a point may have an attribute that is a color, or two attributes that are color and reflectance. According to embodiments, the geometry may be called positions, geometry information, geometry data, or the like, and the attribute may be called attributes, attribute information, attribute data, or the like. The point cloud content providing system (e.g., the point cloud transmission device 10000 or the point cloud video acquirer 10001) may secure point cloud data from information (e.g., depth information, color information, etc.) related to the acquisition process of the point cloud video.
The point cloud content providing system (e.g., the transmission device 10000 or the point cloud video encoder 10002) according to the embodiments may encode the point cloud data (20001). The point cloud content providing system may encode the point cloud data based on point cloud compression coding. As described above, the point cloud data may include the geometry and attributes of a point. Accordingly, the point cloud content providing system may perform geometry encoding of encoding the geometry and output a geometry bitstream. The point cloud content providing system may perform attribute encoding of encoding attributes and output an attribute bitstream. According to embodiments, the point cloud content providing system may perform the attribute encoding based on the geometry encoding. The geometry bitstream and the attribute bitstream according to the embodiments may be multiplexed and output as one bitstream. The bitstream according to the embodiments may further contain signaling information related to the geometry encoding and attribute encoding.
The point cloud content providing system (e.g., the transmission device 10000 or the transmitter 10003) according to the embodiments may transmit the encoded point cloud data (20002). As illustrated in
The point cloud content providing system (e.g., the reception device 10004 or the receiver 10005) according to the embodiments may receive the bitstream containing the encoded point cloud data. In addition, the point cloud content providing system (e.g., the reception device 10004 or the receiver 10005) may demultiplex the bitstream.
The point cloud content providing system (e.g., the reception device 10004 or the point cloud video decoder 10005) may decode the encoded point cloud data (e.g., the geometry bitstream, the attribute bitstream) transmitted in the bitstream. The point cloud content providing system (e.g., the reception device 10004 or the point cloud video decoder 10005) may decode the point cloud video data based on the signaling information related to encoding of the point cloud video data contained in the bitstream. The point cloud content providing system (e.g., the reception device 10004 or the point cloud video decoder 10005) may decode the geometry bitstream to reconstruct the positions (geometry) of points. The point cloud content providing system may reconstruct the attributes of the points by decoding the attribute bitstream based on the reconstructed geometry. The point cloud content providing system (e.g., the reception device 10004 or the point cloud video decoder 10005) may reconstruct the point cloud video based on the positions according to the reconstructed geometry and the decoded attributes.
The point cloud content providing system according to the embodiments (e.g., the reception device 10004 or the renderer 10007) may render the decoded point cloud data (20004). The point cloud content providing system (e.g., the reception device 10004 or the renderer 10007) may render the geometry and attributes decoded through the decoding process, using various rendering methods. Points in the point cloud content may be rendered to a vertex having a certain thickness, a cube having a specific minimum size centered on the corresponding vertex position, or a circle centered on the corresponding vertex position. All or part of the rendered point cloud content is provided to the user through a display (e.g., a VR/AR display, a general display, etc.).
The point cloud content providing system (e.g., the reception device 10004) according to the embodiments may secure feedback information (20005). The point cloud content providing system may encode and/or decode point cloud data based on the feedback information. The feedback information and the operation of the point cloud content providing system according to the embodiments are the same as the feedback information and the operation described with reference to
Point cloud content includes a point cloud video (images and/or videos) representing an object and/or environment located in various 3D spaces (e.g., a 3D space representing a real environment, a 3D space representing a virtual environment, etc.). Accordingly, the point cloud content providing system according to the embodiments may capture a point cloud video using one or more cameras (e.g., an infrared camera capable of securing depth information, an RGB camera capable of extracting color information corresponding to the depth information, etc.), a projector (e.g., an infrared pattern projector to secure depth information), a LiDAR, or the like. The point cloud content providing system according to the embodiments may extract the shape of geometry composed of points in a 3D space from the depth information and extract the attributes of each point from the color information to secure point cloud data. An image and/or video according to the embodiments may be captured based on at least one of the inward-facing technique and the outward-facing technique.
The left part of
The right part of
As shown in the figure, the point cloud content may be generated based on the capturing operation of one or more cameras. In this case, the coordinate system may differ among the cameras, and accordingly the point cloud content providing system may calibrate one or more cameras to set a global coordinate system before the capturing operation. In addition, the point cloud content providing system may generate point cloud content by synthesizing an arbitrary image and/or video with an image and/or video captured by the above-described capture technique. The point cloud content providing system may not perform the capturing operation described in
The point cloud content providing system may generate one piece of point cloud content by performing coordinate transformation on points of the point cloud video secured from each camera. The point cloud content providing system may perform coordinate transformation on the points based on the coordinates of the position of each camera. Accordingly, the point cloud content providing system may generate content representing one wide range, or may generate point cloud content having a high density of points.
As described with reference to
The point cloud encoder according to the embodiments includes a coordinate transformer (Transform coordinates) 40000, a quantizer (Quantize and remove points (voxelize)) 40001, an octree analyzer (Analyze octree) 40002, and a surface approximation analyzer (Analyze surface approximation) 40003, an arithmetic encoder (Arithmetic encode) 40004, a geometry reconstructor (Reconstruct geometry) 40005, a color transformer (Transform colors) 40006, an attribute transformer (Transform attributes) 40007, a RAHT transformer (RAHT) 40008, an LOD generator (Generate LOD) 40009, a lifting transformer (Lifting) 40010, a coefficient quantizer (Quantize coefficients) 40011, and/or an arithmetic encoder (Arithmetic encode) 40012.
The coordinate transformer 40000, the quantizer 40001, the octree analyzer 40002, the surface approximation analyzer 40003, the arithmetic encoder 40004, and the geometry reconstructor 40005 may perform geometry encoding. The geometry encoding according to the embodiments may include octree geometry coding, direct coding, trisoup geometry encoding, and entropy encoding. The direct coding and trisoup geometry encoding are applied selectively or in combination. The geometry encoding is not limited to the above-described example.
As shown in the figure, the coordinate transformer 40000 according to the embodiments receives positions and transforms the same into coordinates. For example, the positions may be transformed into position information in a three-dimensional space (e.g., a three-dimensional space represented by an XYZ coordinate system). The position information in the three-dimensional space according to the embodiments may be referred to as geometry information.
The quantizer 40001 according to the embodiments quantizes the geometry. For example, the quantizer 40001 may quantize the points based on a minimum position value of all points (e.g., a minimum value on each of the X, Y, and Z axes). The quantizer 40001 performs a quantization operation of multiplying the difference between the minimum position value and the position value of each point by a preset quantization scale value and then finding the nearest integer value by rounding the value obtained through the multiplication. Thus, one or more points may have the same quantized position (or position value). The quantizer 40001 according to the embodiments performs voxelization based on the quantized positions to reconstruct quantized points. As in the case of a pixel, which is the minimum unit containing 2D image/video information, points of point cloud content (or 3D point cloud video) according to the embodiments may be included in one or more voxels. The term voxel, which is a compound of volume and pixel, refers to a 3D cubic space generated when a 3D space is divided into units (unit=1.0) based on the axes representing the 3D space (e.g., X-axis, Y-axis, and Z-axis). The quantizer 40001 may match groups of points in the 3D space with voxels. According to embodiments, one voxel may include only one point. According to embodiments, one voxel may include one or more points. In order to express one voxel as one point, the position of the center of a voxel may be set based on the positions of one or more points included in the voxel. In this case, attributes of all positions included in one voxel may be combined and assigned to the voxel.
The octree analyzer 40002 according to the embodiments performs octree geometry coding (or octree coding) to present voxels in an octree structure. The octree structure represents points matched with voxels, based on the octal tree structure.
The surface approximation analyzer 40003 according to the embodiments may analyze and approximate the octree. The octree analysis and approximation according to the embodiments is a process of analyzing a region containing a plurality of points to efficiently provide octree and voxelization.
The arithmetic encoder 40004 according to the embodiments performs entropy encoding on the octree and/or the approximated octree. For example, the encoding scheme includes arithmetic encoding. As a result of the encoding, a geometry bitstream is generated.
The color transformer 40006, the attribute transformer 40007, the RAHT transformer 40008, the LOD generator 40009, the lifting transformer 40010, the coefficient quantizer 40011, and/or the arithmetic encoder 40012 perform attribute encoding. As described above, one point may have one or more attributes. The attribute encoding according to the embodiments is equally applied to the attributes that one point has. However, when an attribute (e.g., color) includes one or more elements, attribute encoding is independently applied to each element. The attribute encoding according to the embodiments includes color transform coding, attribute transform coding, region adaptive hierarchical transform (RAHT) coding, interpolation-based hierarchical nearest-neighbor prediction (prediction transform) coding, and interpolation-based hierarchical nearest-neighbor prediction with an update/lifting step (lifting transform) coding. Depending on the point cloud content, the RAHT coding, the prediction transform coding and the lifting transform coding described above may be selectively used, or a combination of one or more of the coding schemes may be used. The attribute encoding according to the embodiments is not limited to the above-described example.
The color transformer 40006 according to the embodiments performs color transform coding of transforming color values (or textures) included in the attributes. For example, the color transformer 40006 may transform the format of color information (for example, from RGB to YCbCr). The operation of the color transformer 40006 according to embodiments may be optionally applied according to the color values included in the attributes.
The geometry reconstructor 40005 according to the embodiments reconstructs (decompresses) the octree and/or the approximated octree. The geometry reconstructor 40005 reconstructs the octree/voxels based on the result of analyzing the distribution of points. The reconstructed octree/voxels may be referred to as reconstructed geometry (restored geometry).
The attribute transformer 40007 according to the embodiments performs attribute transformation to transform the attributes based on the reconstructed geometry and/or the positions on which geometry encoding is not performed. As described above, since the attributes are dependent on the geometry, the attribute transformer 40007 may transform the attributes based on the reconstructed geometry information. For example, based on the position value of a point included in a voxel, the attribute transformer 40007 may transform the attribute of the point at the position. As described above, when the position of the center of a voxel is set based on the positions of one or more points included in the voxel, the attribute transformer 40007 transforms the attributes of the one or more points. When the trisoup geometry encoding is performed, the attribute transformer 40007 may transform the attributes based on the trisoup geometry encoding.
The attribute transformer 40007 may perform the attribute transformation by calculating the average of attributes or attribute values of neighboring points (e.g., color or reflectance of each point) within a specific position/radius from the position (or position value) of the center of each voxel. The attribute transformer 40007 may apply a weight according to the distance from the center to each point in calculating the average. Accordingly, each voxel has a position and a calculated attribute (or attribute value).
The attribute transformer 40007 may search for neighboring points existing within a specific position/radius from the position of the center of each voxel based on the K-D tree or the Morton code. The K-D tree is a binary search tree and supports a data structure capable of managing points based on the positions such that nearest neighbor search (NNS) may be performed quickly. The Morton code is generated by presenting coordinates (e.g., (x, y, z)) representing 3D positions of all points as bit values and mixing the bits. For example, when the coordinates representing the position of a point are (5, 9, 1), the bit values for the coordinates are (0101, 1001, 0001). Mixing the bit values according to the bit index in order of z, y, and x yields 010001000111. This value is expressed as a decimal number of 1095. That is, the Morton code value of the point having coordinates (5, 9, 1) is 1095. The attribute transformer 40007 may order the points based on the Morton code values and perform NNS through a depth-first traversal process. After the attribute transformation operation, the K-D tree or the Morton code is used when the NNS is needed in another transformation process for attribute coding.
As shown in the figure, the transformed attributes are input to the RAHT transformer 40008 and/or the LOD generator 40009.
The RAHT transformer 40008 according to the embodiments performs RAHT coding for predicting attribute information based on the reconstructed geometry information. For example, the RAHT transformer 40008 may predict attribute information of a node at a higher level in the octree based on the attribute information associated with a node at a lower level in the octree.
The LOD generator 40009 according to the embodiments generates a level of detail (LOD) to perform prediction transform coding. The LOD according to the embodiments is a degree of detail of point cloud content. As the LOD value decrease, it indicates that the detail of the point cloud content is degraded. As the LOD value increases, it indicates that the detail of the point cloud content is enhanced. Points may be classified by the LOD.
The lifting transformer 40010 according to the embodiments performs lifting transform coding of transforming the attributes a point cloud based on weights. As described above, lifting transform coding may be optionally applied.
The coefficient quantizer 40011 according to the embodiments quantizes the attribute-coded attributes based on coefficients.
The arithmetic encoder 40012 according to the embodiments encodes the quantized attributes based on arithmetic coding.
Although not shown in the figure, the elements of the point cloud encoder of
As described with reference to
The upper part of
As shown in the middle of the upper part of
The lower part of
The point cloud encoder (e.g., the point cloud encoder of
Accordingly, for the above-described specific region (or a node other than the leaf node of the octree), the point cloud encoder according to the embodiments may skip voxelization and perform direct coding to directly code the positions of points included in the specific region. The coordinates of a direct coding point according to the embodiments are referred to as direct coding mode (DCM). The point cloud encoder according to the embodiments may also perform trisoup geometry encoding, which is to reconstruct the positions of the points in the specific region (or node) based on voxels, based on a surface model. The trisoup geometry encoding is geometry encoding that represents an object as a series of triangular meshes. Accordingly, the point cloud decoder may generate a point cloud from the mesh surface. The direct coding and trisoup geometry encoding according to the embodiments may be selectively performed. In addition, the direct coding and trisoup geometry encoding according to the embodiments may be performed in combination with octree geometry coding (or octree coding).
To perform direct coding, the option to use the direct mode for applying direct coding should be activated. A node to which direct coding is to be applied is not a leaf node, and points less than a threshold should be present within a specific node. In addition, the total number of points to which direct coding is to be applied should not exceed a preset threshold. When the conditions above are satisfied, the point cloud encoder (or the arithmetic encoder 40004) according to the embodiments may perform entropy coding on the positions (or position values) of the points.
The point cloud encoder (e.g., the surface approximation analyzer 40003) according to the embodiments may determine a specific level of the octree (a level less than the depth d of the octree), and the surface model may be used staring with that level to perform trisoup geometry encoding to reconstruct the positions of points in the region of the node based on voxels (Trisoup mode). The point cloud encoder according to the embodiments may specify a level at which trisoup geometry encoding is to be applied. For example, when the specific level is equal to the depth of the octree, the point cloud encoder does not operate in the trisoup mode. In other words, the point cloud encoder according to the embodiments may operate in the trisoup mode only when the specified level is less than the value of depth of the octree. The 3D cube region of the nodes at the specified level according to the embodiments is called a block. One block may include one or more voxels. The block or voxel may correspond to a brick. Geometry is represented as a surface within each block. The surface according to embodiments may intersect with each edge of a block at most once.
One block has 12 edges, and accordingly there are at least 12 intersections in one block. Each intersection is called a vertex (or apex). A vertex present along an edge is detected when there is at least one occupied voxel adjacent to the edge among all blocks sharing the edge. The occupied voxel according to the embodiments refers to a voxel containing a point. The position of the vertex detected along the edge is the average position along the edge of all voxels adjacent to the edge among all blocks sharing the edge.
Once the vertex is detected, the point cloud encoder according to the embodiments may perform entropy encoding on the starting point (x, y, z) of the edge, the direction vector (Δx, Δy, Δz) of the edge, and the vertex position value (relative position value within the edge). When the trisoup geometry encoding is applied, the point cloud encoder according to the embodiments (e.g., the geometry reconstructor 40005) may generate restored geometry (reconstructed geometry) by performing the triangle reconstruction, up-sampling, and voxelization processes.
The vertices positioned at the edge of the block determine a surface that passes through the block. The surface according to the embodiments is a non-planar polygon. In the triangle reconstruction process, a surface represented by a triangle is reconstructed based on the starting point of the edge, the direction vector of the edge, and the position values of the vertices. The triangle reconstruction process is performed by: i) calculating the centroid value of each vertex, ii) subtracting the center value from each vertex value, and iii) estimating the sum of the squares of the values obtained by the subtraction.
The minimum value of the sum is estimated, and the projection process is performed according to the axis with the minimum value. For example, when the element x is the minimum, each vertex is projected on the x-axis with respect to the center of the block, and projected on the (y, z) plane. When the values obtained through projection on the (y, z) plane are (ai, bi), the value of θ is estimated through atan2(bi, ai), and the vertices are ordered based on the value of θ. The table below shows a combination of vertices for creating a triangle according to the number of the vertices. The vertices are ordered from 1 to n. The table below shows that for four vertices, two triangles may be constructed according to combinations of vertices. The first triangle may consist of vertices 1, 2, and 3 among the ordered vertices, and the second triangle may consist of vertices 3, 4, and 1 among the ordered vertices.
Triangles formed from vertices ordered 1, . . . , n
The upsampling process is performed to add points in the middle along the edge of the triangle and perform voxelization. The added points are generated based on the upsampling factor and the width of the block. The added points are called refined vertices. The point cloud encoder according to the embodiments may voxelize the refined vertices. In addition, the point cloud encoder may perform attribute encoding based on the voxelized positions (or position values).
In order to increase the compression efficiency of the point cloud video, the point cloud encoder according to the embodiments may perform entropy coding based on context adaptive arithmetic coding.
As described with reference to
The right part of
As described with reference to
The point cloud encoder (e.g., the LOD generator 40009) may classify (reorganize) points by LOD. The figure shows the point cloud content corresponding to LODs. The leftmost picture in the figure represents original point cloud content. The second picture from the left of the figure represents distribution of the points in the lowest LOD, and the rightmost picture in the figure represents distribution of the points in the highest LOD. That is, the points in the lowest LOD are sparsely distributed, and the points in the highest LOD are densely distributed. That is, as the LOD rises in the direction pointed by the arrow indicated at the bottom of the figure, the space (or distance) between points is narrowed.
As described with reference to
The upper part of
As described with reference to
The point cloud encoder according to the embodiments may generate a predictor for points to perform prediction transform coding for setting a predicted attribute (or predicted attribute value) of each point. That is, N predictors may be generated for N points. The predictor according to the embodiments may calculate a weight (=1/distance) based on the LOD value of each point, indexing information about neighboring points present within a set distance for each LOD, and a distance to the neighboring points.
The predicted attribute (or attribute value) according to the embodiments is set to the average of values obtained by multiplying the attributes (or attribute values) (e.g., color, reflectance, etc.) of neighbor points set in the predictor of each point by a weight (or weight value) calculated based on the distance to each neighbor point. The point cloud encoder according to the embodiments (e.g., the coefficient quantizer 40011) may quantize and inversely quantize the residuals (which may be called residual attributes, residual attribute values, or attribute prediction residuals) obtained by subtracting a predicted attribute (attribute value) from the attribute (attribute value) of each point. The quantization process is configured as shown in the following table.
When the predictor of each point has neighbor points, the point cloud encoder (e.g., the arithmetic encoder 40012) according to the embodiments may perform entropy coding on the quantized and inversely quantized residual values as described above. When the predictor of each point has no neighbor point, the point cloud encoder according to the embodiments (e.g., the arithmetic encoder 40012) may perform entropy coding on the attributes of the corresponding point without performing the above-described operation.
The point cloud encoder according to the embodiments (e.g., the lifting transformer 40010) may generate a predictor of each point, set the calculated LOD and register neighbor points in the predictor, and set weights according to the distances to neighbor points to perform lifting transform coding. The lifting transform coding according to the embodiments is similar to the above-described prediction transform coding, but differs therefrom in that weights are cumulatively applied to attribute values. The process of cumulatively applying weights to the attribute values according to embodiments is configured as follows.
1) Create an array Quantization Weight (QW) for storing the weight value of each point. The initial value of all elements of QW is 1.0. Multiply the QW values of the predictor indexes of the neighbor nodes registered in the predictor by the weight of the predictor of the current point, and add the values obtained by the multiplication.
2) Lift prediction process: Subtract the value obtained by multiplying the attribute value of the point by the weight from the existing attribute value to calculate a predicted attribute value.
3) Create temporary arrays called updateweight and update and initialize the temporary arrays to zero.
4) Cumulatively add the weights calculated by multiplying the weights calculated for all predictors by a weight stored in the QW corresponding to a predictor index to the updateweight array as indexes of neighbor nodes. Cumulatively add, to the update array, a value obtained by multiplying the attribute value of the index of a neighbor node by the calculated weight.
5) Lift update process: Divide the attribute values of the update array for all predictors by the weight value of the updateweight array of the predictor index, and add the existing attribute value to the values obtained by the division.
6) Calculate predicted attributes by multiplying the attribute values updated through the lift update process by the weight updated through the lift prediction process (stored in the QW) for all predictors. The point cloud encoder (e.g., coefficient quantizer 40011) according to the embodiments quantizes the predicted attribute values. In addition, the point cloud encoder (e.g., the arithmetic encoder 40012) performs entropy coding on the quantized attribute values.
The point cloud encoder (e.g., the RAHT transformer 40008) according to the embodiments may perform RAHT transform coding in which attributes of nodes of a higher level are predicted using the attributes associated with nodes of a lower level in the octree. RAHT transform coding is an example of attribute intra coding through an octree backward scan. The point cloud encoder according to the embodiments scans the entire region from the voxel and repeats the merging process of merging the voxels into a larger block at each step until the root node is reached. The merging process according to the embodiments is performed only on the occupied nodes. The merging process is not performed on the empty node. The merging process is performed on an upper node immediately above the empty node.
The equation below represents a RAHT transformation matrix. In the equation, gl
Here, gl−1
The value of gDC is also quantized and subjected to entropy coding like the high-pass coefficients.
The point cloud decoder illustrated in
The point cloud decoder illustrated in
As described with reference to
The point cloud decoder according to the embodiments includes an arithmetic decoder (Arithmetic decode) 11000, an octree synthesizer (Synthesize octree) 11001, a surface approximation synthesizer (Synthesize surface approximation) 11002, and a geometry reconstructor (Reconstruct geometry) 11003, a coordinate inverse transformer (Inverse transform coordinates) 11004, an arithmetic decoder (Arithmetic decode) 11005, an inverse quantizer (Inverse quantize) 11006, a RAHT transformer 11007, an LOD generator (Generate LOD) 11008, an inverse lifter (inverse lifting) 11009, and/or a color inverse transformer (Inverse transform colors) 11010.
The arithmetic decoder 11000, the octree synthesizer 11001, the surface approximation synthesizer 11002, and the geometry reconstructor 11003, and the coordinate inverse transformer 11004 may perform geometry decoding. The geometry decoding according to the embodiments may include direct coding and trisoup geometry decoding. The direct coding and trisoup geometry decoding are selectively applied. The geometry decoding is not limited to the above-described example, and is performed as a reverse process to the geometry encoding described with reference to
The arithmetic decoder 11000 according to the embodiments decodes the received geometry bitstream based on the arithmetic coding. The operation of the arithmetic decoder 11000 corresponds to the reverse process to the arithmetic encoder 40004.
The octree synthesizer 11001 according to the embodiments may generate an octree by acquiring an occupancy code from the decoded geometry bitstream (or information on the geometry secured as a result of decoding). The occupancy code is configured as described in detail with reference to
When the trisoup geometry encoding is applied, the surface approximation synthesizer 11002 according to the embodiments may synthesize a surface based on the decoded geometry and/or the generated octree.
The geometry reconstructor 11003 according to the embodiments may regenerate geometry based on the surface and/or the decoded geometry. As described with reference to
The coordinate inverse transformer 11004 according to the embodiments may acquire positions of the points by transforming the coordinates based on the reconstructed geometry.
The arithmetic decoder 11005, the inverse quantizer 11006, the RAHT transformer 11007, the LOD generator 11008, the inverse lifter 11009, and/or the color inverse transformer 11010 may perform the attribute decoding described with reference to
The arithmetic decoder 11005 according to the embodiments decodes the attribute bitstream by arithmetic coding.
The inverse quantizer 11006 according to the embodiments inversely quantizes the information about the decoded attribute bitstream or attributes secured as a result of the decoding, and outputs the inversely quantized attributes (or attribute values). The inverse quantization may be selectively applied based on the attribute encoding of the point cloud encoder.
According to embodiments, the RAHT transformer 11007, the LOD generator 11008, and/or the inverse lifter 11009 may process the reconstructed geometry and the inversely quantized attributes. As described above, the RAHT transformer 11007, the LOD generator 11008, and/or the inverse lifter 11009 may selectively perform a decoding operation corresponding to the encoding of the point cloud encoder.
The color inverse transformer 11010 according to the embodiments performs inverse transform coding to inversely transform a color value (or texture) included in the decoded attributes. The operation of the color inverse transformer 11010 may be selectively performed based on the operation of the color transformer 40006 of the point cloud encoder.
Although not shown in the figure, the elements of the point cloud decoder of
The transmission device shown in
The data input unit 12000 according to the embodiments receives or acquires point cloud data. The data input unit 12000 may perform an operation and/or acquisition method the same as or similar to the operation and/or acquisition method of the point cloud video acquirer 10001 (or the acquisition process 20000 described with reference to
The data input unit 12000, the quantization processor 12001, the voxelization processor 12002, the octree occupancy code generator 12003, the surface model processor 12004, the intra/inter-coding processor 12005, and the arithmetic coder 12006 perform geometry encoding. The geometry encoding according to the embodiments is the same as or similar to the geometry encoding described with reference to
The quantization processor 12001 according to the embodiments quantizes geometry (e.g., position values of points). The operation and/or quantization of the quantization processor 12001 is the same as or similar to the operation and/or quantization of the quantizer 40001 described with reference to
The voxelization processor 12002 according to the embodiments voxelizes the quantized position values of the points. The voxelization processor 12002 may perform an operation and/or process the same or similar to the operation and/or the voxelization process of the quantizer 40001 described with reference to
The octree occupancy code generator 12003 according to the embodiments performs octree coding on the voxelized positions of the points based on an octree structure. The octree occupancy code generator 12003 may generate an occupancy code. The octree occupancy code generator 12003 may perform an operation and/or method the same as or similar to the operation and/or method of the point cloud encoder (or the octree analyzer 40002) described with reference to
The surface model processor 12004 according to the embodiments may perform trisoup geometry encoding based on a surface model to reconstruct the positions of points in a specific region (or node) on a voxel basis. The surface model processor 12004 may perform an operation and/or method the same as or similar to the operation and/or method of the point cloud encoder (e.g., the surface approximation analyzer 40003) described with reference to
The intra/inter-coding processor 12005 according to the embodiments may perform intra/inter-coding on point cloud data. The intra/inter-coding processor 12005 may perform coding the same as or similar to the intra/inter-coding described with reference to
The arithmetic coder 12006 according to the embodiments performs entropy encoding on an octree of the point cloud data and/or an approximated octree. For example, the encoding scheme includes arithmetic encoding. The arithmetic coder 12006 performs an operation and/or method the same as or similar to the operation and/or method of the arithmetic encoder 40004.
The metadata processor 12007 according to the embodiments processes metadata about the point cloud data, for example, a set value, and provides the same to a necessary processing process such as geometry encoding and/or attribute encoding. Also, the metadata processor 12007 according to the embodiments may generate and/or process signaling information related to the geometry encoding and/or the attribute encoding. The signaling information according to the embodiments may be encoded separately from the geometry encoding and/or the attribute encoding. The signaling information according to the embodiments may be interleaved.
The color transform processor 12008, the attribute transform processor 12009, the prediction/lifting/RAHT transform processor 12010, and the arithmetic coder 12011 perform the attribute encoding. The attribute encoding according to the embodiments is the same as or similar to the attribute encoding described with reference to
The color transform processor 12008 according to the embodiments performs color transform coding to transform color values included in attributes. The color transform processor 12008 may perform color transform coding based on the reconstructed geometry. The reconstructed geometry is the same as described with reference to
The attribute transform processor 12009 according to the embodiments performs attribute transformation to transform the attributes based on the reconstructed geometry and/or the positions on which geometry encoding is not performed. The attribute transform processor 12009 performs an operation and/or method the same as or similar to the operation and/or method of the attribute transformer 40007 described with reference to
The arithmetic coder 12011 according to the embodiments may encode the coded attributes based on the arithmetic coding. The arithmetic coder 12011 performs an operation and/or method the same as or similar to the operation and/or method of the arithmetic encoder 400012.
The transmission processor 12012 according to the embodiments may transmit each bitstream containing encoded geometry and/or encoded attributes and metadata information, or transmit one bitstream configured with the encoded geometry and/or the encoded attributes and the metadata information. When the encoded geometry and/or the encoded attributes and the metadata information according to the embodiments are configured into one bitstream, the bitstream may include one or more sub-bitstreams. The bitstream according to the embodiments may contain signaling information including a sequence parameter set (SPS) for signaling of a sequence level, a geometry parameter set (GPS) for signaling of geometry information coding, an attribute parameter set (APS) for signaling of attribute information coding, and a tile parameter set (TPS) for signaling of a tile level, and slice data. The slice data may include information about one or more slices. One slice according to embodiments may include one geometry bitstream Geom00 and one or more attribute bitstreams Attr00 and Attr10.
A slice refers to a series of syntax elements representing the entirety or part of a coded point cloud frame.
The TPS according to the embodiments may include information about each tile (e.g., coordinate information and height/size information about a bounding box) for one or more tiles. The geometry bitstream may contain a header and a payload. The header of the geometry bitstream according to the embodiments may contain a parameter set identifier (geom_parameter_set_id), a tile identifier (geom_tile_id) and a slice identifier (geom_slice_id) included in the GPS, and information about the data contained in the payload. As described above, the metadata processor 12007 according to the embodiments may generate and/or process the signaling information and transmit the same to the transmission processor 12012. According to embodiments, the elements to perform geometry encoding and the elements to perform attribute encoding may share data/information with each other as indicated by dotted lines. The transmission processor 12012 according to the embodiments may perform an operation and/or transmission method the same as or similar to the operation and/or transmission method of the transmitter 10003. Details are the same as those described with reference to
The reception device illustrated in
The reception device according to the embodiment may include a receiver 13000, a reception processor 13001, an arithmetic decoder 13002, an occupancy code-based octree reconstruction processor 13003, a surface model processor (triangle reconstruction, up-sampling, voxelization) 13004, an inverse quantization processor 13005, a metadata parser 13006, an arithmetic decoder 13007, an inverse quantization processor 13008, a prediction/lifting/RAHT inverse transform processor 13009, a color inverse transform processor 13010, and/or a renderer 13011. Each element for decoding according to the embodiments may perform a reverse process to the operation of a corresponding element for encoding according to the embodiments.
The receiver 13000 according to the embodiments receives point cloud data. The receiver 13000 may perform an operation and/or reception method the same as or similar to the operation and/or reception method of the receiver 10005 of
The reception processor 13001 according to the embodiments may acquire a geometry bitstream and/or an attribute bitstream from the received data. The reception processor 13001 may be included in the receiver 13000.
The arithmetic decoder 13002, the occupancy code-based octree reconstruction processor 13003, the surface model processor 13004, and the inverse quantization processor 13005 may perform geometry decoding. The geometry decoding according to embodiments is the same as or similar to the geometry decoding described with reference to
The arithmetic decoder 13002 according to the embodiments may decode the geometry bitstream based on arithmetic coding. The arithmetic decoder 13002 performs an operation and/or coding the same as or similar to the operation and/or coding of the arithmetic decoder 11000.
The occupancy code-based octree reconstruction processor 13003 according to the embodiments may reconstruct an octree by acquiring an occupancy code from the decoded geometry bitstream (or information about the geometry secured as a result of decoding). The occupancy code-based octree reconstruction processor 13003 performs an operation and/or method the same as or similar to the operation and/or octree generation method of the octree synthesizer 11001. When the trisoup geometry encoding is applied, the surface model processor 13004 according to the embodiments may perform trisoup geometry decoding and related geometry reconstruction (e.g., triangle reconstruction, up-sampling, voxelization) based on the surface model method. The surface model processor 13004 performs an operation the same as or similar to that of the surface approximation synthesizer 11002 and/or the geometry reconstructor 11003.
The inverse quantization processor 13005 according to the embodiments may inversely quantize the decoded geometry.
The metadata parser 13006 according to the embodiments may parse metadata contained in the received point cloud data, for example, a set value. The metadata parser 13006 may pass the metadata to geometry decoding and/or attribute decoding. The metadata is the same as that described with reference to
The arithmetic decoder 13007, the inverse quantization processor 13008, the prediction/lifting/RAHT inverse transform processor 13009 and the color inverse transform processor 13010 perform attribute decoding. The attribute decoding is the same as or similar to the attribute decoding described with reference to
The arithmetic decoder 13007 according to the embodiments may decode the attribute bitstream by arithmetic coding. The arithmetic decoder 13007 may decode the attribute bitstream based on the reconstructed geometry. The arithmetic decoder 13007 performs an operation and/or coding the same as or similar to the operation and/or coding of the arithmetic decoder 11005.
The inverse quantization processor 13008 according to the embodiments may inversely quantize the decoded attribute bitstream. The inverse quantization processor 13008 performs an operation and/or method the same as or similar to the operation and/or inverse quantization method of the inverse quantizer 11006.
The prediction/lifting/RAHT inverse transform processor 13009 according to the embodiments may process the reconstructed geometry and the inversely quantized attributes. The prediction/lifting/RAHT inverse transform processor 13009 performs one or more of operations and/or decoding the same as or similar to the operations and/or decoding of the RAHT transformer 11007, the LOD generator 11008, and/or the inverse lifter 11009. The color inverse transform processor 13010 according to the embodiments performs inverse transform coding to inversely transform color values (or textures) included in the decoded attributes. The color inverse transform processor 13010 performs an operation and/or inverse transform coding the same as or similar to the operation and/or inverse transform coding of the color inverse transformer 11010. The renderer 13011 according to the embodiments may render the point cloud data.
The structure of
The cloud network 1400 may represent a network that constitutes part of the cloud computing infrastructure or is present in the cloud computing infrastructure. Here, the cloud network 1400 may be configured using a 3G network, 4G or Long Term Evolution (LTE) network, or a 5G network.
The server 1460 may be connected to at least one of the robot 1410, the self-driving vehicle 1420, the XR device 1430, the smartphone 1440, the home appliance 1450, and/or the HMD 1470 over the cloud network 1400 and may assist in at least a part of the processing of the connected devices 1410 to 1470.
The HMD 1470 represents one of the implementation types of the XR device and/or the PCC device according to the embodiments. The HMD type device according to the embodiments includes a communication unit, a control unit, a memory, an I/O unit, a sensor unit, and a power supply unit.
Hereinafter, various embodiments of the devices 1410 to 1450 to which the above-described technology is applied will be described. The devices 1410 to 1450 illustrated in
The XR/PCC device 1430 may employ PCC technology and/or XR (AR+VR) technology, and may be implemented as an HMD, a head-up display (HUD) provided in a vehicle, a television, a mobile phone, a smartphone, a computer, a wearable device, a home appliance, a digital signage, a vehicle, a stationary robot, or a mobile robot.
The XR/PCC device 1430 may analyze 3D point cloud data or image data acquired through various sensors or from an external device and generate position data and attribute data about 3D points. Thereby, the XR/PCC device 1430 may acquire information about the surrounding space or a real object, and render and output an XR object. For example, the XR/PCC device 1430 may match an XR object including auxiliary information about a recognized object with the recognized object and output the matched XR object.
The XR/PCC device 1430 may be implemented as a mobile phone 1440 by applying PCC technology.
The mobile phone 1440 may decode and display point cloud content based on the PCC technology.
The self-driving vehicle 1420 may be implemented as a mobile robot, a vehicle, an unmanned aerial vehicle, or the like by applying the PCC technology and the XR technology.
The self-driving vehicle 1420 to which the XR/PCC technology is applied may represent a self-driving vehicle provided with means for providing an XR image, or a self-driving vehicle that is a target of control/interaction in the XR image. In particular, the self-driving vehicle 1420 which is a target of control/interaction in the XR image may be distinguished from the XR device 1430 and may be operatively connected thereto.
The self-driving vehicle 1420 having means for providing an XR/PCC image may acquire sensor information from sensors including a camera, and output the generated XR/PCC image based on the acquired sensor information. For example, the self-driving vehicle 1420 may have an HUD and output an XR/PCC image thereto, thereby providing an occupant with an XR/PCC object corresponding to a real object or an object present on the screen.
When the XR/PCC object is output to the HUD, at least a part of the XR/PCC object may be output to overlap the real object to which the occupant's eyes are directed. On the other hand, when the XR/PCC object is output on a display provided inside the self-driving vehicle, at least a part of the XR/PCC object may be output to overlap an object on the screen. For example, the self-driving vehicle 1220 may output XR/PCC objects corresponding to objects such as a road, another vehicle, a traffic light, a traffic sign, a two-wheeled vehicle, a pedestrian, and a building.
The virtual reality (VR) technology, the augmented reality (AR) technology, the mixed reality (MR) technology and/or the point cloud compression (PCC) technology according to the embodiments are applicable to various devices.
In other words, the VR technology is a display technology that provides only CG images of real-world objects, backgrounds, and the like. On the other hand, the AR technology refers to a technology that shows a virtually created CG image on the image of a real object. The MR technology is similar to the AR technology described above in that virtual objects to be shown are mixed and combined with the real world. However, the MR technology differs from the AR technology in that the AR technology makes a clear distinction between a real object and a virtual object created as a CG image and uses virtual objects as complementary objects for real objects, whereas the MR technology treats virtual objects as objects having equivalent characteristics as real objects. More specifically, an example of MR technology applications is a hologram service.
Recently, the VR, AR, and MR technologies are sometimes referred to as extended reality (XR) technology rather than being clearly distinguished from each other. Accordingly, embodiments of the present disclosure are applicable to any of the VR, AR, MR, and XR technologies. The encoding/decoding based on PCC, V-PCC, and G-PCC techniques is applicable to such technologies.
The PCC method/device according to the embodiments may be applied to a vehicle that provides a self-driving service.
A vehicle that provides the self-driving service is connected to a PCC device for wired/wireless communication.
When the point cloud data (PCC) transmission/reception device according to the embodiments is connected to a vehicle for wired/wireless communication, the device may receive/process content data related to an AR/VR/PCC service, which may be provided together with the self-driving service, and transmit the same to the vehicle. In the case where the PCC transmission/reception device is mounted on a vehicle, the PCC transmission/reception device may receive/process content data related to the AR/VR/PCC service according to a user input signal input through a user interface device and provide the same to the user. The vehicle or the user interface device according to the embodiments may receive a user input signal. The user input signal according to the embodiments may include a signal indicating the self-driving service.
As described with reference to
According to embodiments, point cloud data may be classified into category 1 for static point cloud data, category 2 for dynamic point cloud data, and category 3 for point cloud data acquired through dynamic movement, depending on the type and acquisition method of the point cloud data. Category 1 is composed of a point cloud of a single frame with a high density of points for an object or space. Category 3 data may be divided into as frame-based data with multiple frames acquired while moving, and fused data of a single frame matching a point cloud acquired for a large space by a LiDAR sensor with a color image acquired as a 2D image.
According to embodiments, inter-prediction (coding/decoding) may be used to efficiently compress three-dimensional point cloud data with multiple frames over time, such as frame-based point cloud data with multiple frames. Inter-prediction coding/decoding may be applied to geometry information and/or attribute information. Inter-prediction may be referred to as inter-image prediction or inter-frame prediction, and intra-prediction may be referred to as intra-frame prediction.
Embodiments relate to methods of increasing compression efficiency of attributes of geometry-based point cloud compression (G-PCC) for compressing three-dimensional point cloud data.
Embodiments may increase compression efficiency of attribute information through a method of selecting a neighbor point set and an attribute inter-prediction method used for inter(−frame) prediction of attribute information.
The point cloud data transmission/reception device/method according to embodiments may perform the followings:
Selection of a neighbor point set for attribute information inter-prediction;
Attribute inter-prediction using attribute change vector on a per prediction unit (PU) basis
Signaling related to selection of a neighbor point set and inter-prediction
Point cloud data is composed of a set of points, and each of the points may include geometry information and attribute information. The geometry information is three-dimensional position (X, Y. Z) information, and the attribute information is values of colors (RGB, YUV, etc.) and/or reflectance. The G-PCC encoding process may include compressing the geometry and compressing the attribute information based on the geometry reconstructed with position information changed through compression (reconstructed geometry=decoded geometry).
The G-PCC decoding process may include receiving an encoded geometry bitstream and attribute bitstream, decoding geometry, and decoding attribute information based on the geometry reconstructed through the decoding.
In the attribute information compression process according to the embodiments, prediction transform, lifting transform, or RAHT is used as a technique. In the prediction transform and the lifting transform, points may be grouped by dividing the same into Levels of Detail (hereinafter referred to as LOD). This operation may be referred to as LOD generation. Hereinafter, a group having different LODs may be referred to as an LOD set. Here, i denotes the level of LOD and is an integer starting from 0. LOD_0 is a set composed of points having the longest distances therebetween. As i increases, the distance between points belonging to LOD_i decreases (see
The distance-based LOD generation is a LOD generation method for grouping points based on a distance between points according to geometry information about the points. For example, at least distances between points belonging to a specific LOD level may be greater than or equal to a distance.
The decimation-based LOD generation may be a LOD generation method for grouping points based on an interval of sorted points. For example, an LOD may be generated by assigning an index to points sorted by any criterion in order and grouping them by sampling points at 3-index intervals.
The octree-based LOD generation is a method of generating an LOD by sampling points based on a node (or a block) of an octree. The LOD levels may correspond to nodes of the octree. In sampling points from an LOD level to generate the next LOD level, points may be sampled from an octree node corresponding to the LOD level to configure the next LOD level.
According to embodiments, after generating the LOD set, the transmission/reception device/method may search for the X (>0) nearest neighbors in a group having the same or lower LOD level (a group in which the distance between nodes is large) based on the LOD set, and register the nearest neighbors as a neighbor set in the predictor. X is the maximum number of points that may be configured as neighbors. X may be input as a user parameter.
According to embodiments, the transmission/reception device/method may find the neighbors of P3 belonging to LOD_1 in LOD_0 and LOD_1 as shown in the example of
Every point may have one predictor. The attribute values of points may be predicted from their neighbors registered in the predictor. The predictor may predict the attribute value of the current point from the neighboring set. The residual between the original attribute value of the current point and the attribute value predicted by the predictor of the current point may be encoded and signaled to the reception device according to the embodiments.
According to embodiments, the transmission/reception device/method may carry out a method of searching for a neighbor set and a method of inter-predicting a prediction unit (PU)-based attribute inter-prediction method, which may be used between frames for attribute inter-prediction.
According to embodiments, the transmission/reception device/method may change a method of configuring a neighbor set for inter-prediction of attribute information, and may support optimization of attribute prediction through a change value in a PU of an attribute in performing PU-based attribute inter-prediction. The neighbor set configuration method and the attribute prediction method may be applied to both the transmission device and the reception device.
According to embodiments, the transmission/reception device/method may configure a neighbor set from a reference frame, and may increase attribute compression efficiency with inter-prediction through a PU.
According to embodiments, the transmission/reception device/method may generate a neighbor set based on the LODs of the current frame and the reference frame. The neighbor set may be configured to be as large as the maximum number of neighbor points that is set in intra-prediction (prediction in the current frame) or inter-prediction (of reference frame).
According to embodiments, after generating the LOD set in intra-prediction, the transmission/reception device/method may search for the X (>0) nearest neighbors in a group having the same or lower LOD level (a group in which the distance between nodes is large) based on the LOD set, and register the nearest neighbors as an intra-neighbor set in the predictor.
For the reference frame, which corresponds to pre-processed data, an LOD may have already been generated. When the intra LOD to which the current point for which a neighbor set is searched for in the current frame is LOD_n, the X (>0) nearest neighbors may be found in a group having the same or lower LOD (a group in which the distance between nodes is large) from the LOD generated from the reference frame and registered as an inter neighbor set in the predictor.
For example, when the current point belongs to LOD_n of the LOD set of the current frame, the nearest neighbor points may be searched for among the points belonging to LOD_n or a lower LOD in the LOD set of the reference frame for the current point and registered as an inter neighbor set in the predictor.
The current frame and the reference frame may be referred to as a first frame and a second frame, or the like. The LOD of the current frame and the LOD of the reference frame may be referred to as a first LOD and a second LOD, or the like.
According to embodiments, the transmission/reception method/device may not generate the LOD in the inter-compression process. The transmission/reception method/device may construct an octree in the attribute compression process, rather than generating the LOD, and may find a node of the octree matching the PU of the geometry. As a PU of the reference frame, a PU matching the octree node of the current frame may be found based on the motion vector. The PU of the reference frame may be referred to as PUref, and the matched PU of the current frame may be referred to as PUcur. The neighbor set may be configured to be as large as the maximum number of neighbors in the intra-prediction (in the current frame) and/or the inter-prediction (of the reference frame), respectively.
According to embodiments, in predicting attribute information, the transmission/reception device/method may search for a matching PU of the reference frame based on a node (or a block) of an octree including the current point and may search for the nearest neighbors of the current point in the PU of the reference frame and register the found neighbors in the predictor. The predictor may predict attribute information about the current point based on the found nearest neighbors. In this case, the node of the octree to which the current point belongs in the current frame may correspond to the PU of the current frame. The PU of the current frame may be represented as PUcur, and the PU of the reference frame may be represented as PUref.
A PU according to embodiments may be referred to as a prediction region, a prediction zone, a prediction node, a prediction block, or the like, and may represent a unit serving as a reference for prediction.
According to embodiments, the transmission/reception device/method may search for X (>0) nearest neighbors among adjacent nodes that are around PUcur, and may register the nearest neighbors as an intra neighbor set in the predictor. The range of adjacent nodes of PUcur may be set by receiving an input.
The neighbor search may be performed in the following manner. Based on the octree level of the PU, Morton codes may be shifted to local Morton codes and sorted, and then the nearest neighbors of a point within a specific range (search_range) based on the nearest Morton code may be searched for.
According to embodiments, the transmission/reception device/method may search for X (>0) nearest neighbors among adjacent nodes that are around PUref and PUref, and may register the nearest neighbors as an inter neighbor set in the predictor. The range of adjacent nodes of PUref may be set by receiving an input. It may be set to be the same as PUcur.
The neighbor search may be performed in the following manner. Based on the octree level of the PU, Morton codes may be shifted to local Morton codes and sorted, and then the nearest neighbors of a point within a specific range (search_range) based on the nearest Morton code may be searched for.
According to embodiments, the transmission/reception device/method may search for neighbors in a PU of a current frame to which a current point belongs and a region adjacent to the PU. Further, the transmission/reception device/method may search for neighbors in a PU of a reference frame corresponding to the PU of the current frame and a region adjacent to the PU. The found neighbors may be registered in the predictor for the current point, and may be used to predict attribute information about the current point. The unit may be referred to as various terms, such as a node, a block, a region, and a zone.
The transmission/reception device/method may not additionally generate the LOD in the inter-compression process. The transmission/reception method/device may construct an octree in the attribute compression process, rather than configuring the LOD, and may find a node of the octree matching PUcur of the geometry. The PUref of the reference frame may be searched for through an octree node of the reference frame matching the octree node of the current frame matched based on the motion vector.
The PU of the reference frame may be referred to as a reference PU (PUref), and the matched PU of the current frame may be referred to as a current PU (PUcur).
According to embodiments, the transmission/reception device/method may obtain an average color value of points belonging to PUcur, and obtain an average color value of points belonging to PUref and adjacent nodes of PUref, and may change the PUref to a node having the smallest difference between PUcur and the average color value. Thereby, a motion change of the geometry of the point and an error caused by a difference in color may be prevented. The information about the change of matching of PUref may be signaled to the reception device (or decoder). The neighbor set may be configured to be as large as the maximum number of neighbors in the intra-frame manner (in the current frame), or as large as the maximum number of neighbors in the inter-frame manner (of the reference frame).
A PU according to embodiments may be referred to as a prediction region, a prediction zone, a prediction node, a prediction block, or the like, and may represent a unit serving as a reference for prediction.
According to embodiments, the transmission/reception device/method may obtain an average attribute value of points belonging to PUcur, obtain an average attribute value of points belonging to PUref and adjacent nodes of PUref in the reference frame, and may change PUref to a node (or a region) having the smallest difference between PUcur and the average color value. The attribute information to be compared may include color and reflectance.
Alternatively, according to embodiments, the transmission/reception device/method may obtain an average attribute value of points belonging to PUref and adjacent nodes of PUref in the reference frame, and may change PUref to the node (or region) having the smallest difference from the attribute value of the current point. The attribute information to be compared may include color and reflectance.
When a neighbor set is generated based on the PU, the attribute change vector may be generated between the PU of the current frame (PUcur) and matching PUref of the reference frame for the attribute information, similar to the motion vector prediction for each PU of the geometry. The attribute change vector is a vector indicating a change in attribute value, and may be, for example, a color change vector indicating a difference between R, G, and B values or a vector indicating a difference in other attribute information.
The point cloud data may be captured with different colors depending on the surrounding environment, even when it has the same color. For example, in the case of a road, the color may be changed consistently depending on the direction of light. The PU-specific color change vector is additional information for this case. By applying the color change vector to the PU of the reference frame (PUref), the residual value may decrease and the size of the bitstream may be reduced. The PU-specific color change vector may be signaled to the reception device (or decoder), and information indicating whether to apply the attribute change vector may be determined through rate distortion optimization (RDO), and may be signaled to the reception device (or decoder).
An encoder may be referred to as an encoding device, and a decoder may be referred to as a decoding device.
The transmission device/method of
Referring to
A neighbor set configurator 1640 of the transmission device/method may perform a neighbor set configuration according to the above-described embodiments. The range of an adjacent region (or nodes) for configuring the neighbor set may be a parameter input from the user.
The attribute information encoder of
According to embodiments, the transmission/reception device/method may determine whether to configure an LOD (1610), and an LOD configurator 1620 or a PU configurator 1630 may perform an operation according to the determination. The LOD configurator 1620 may configure an LOD based on the point cloud data, and the PU configurator 1630 may configure a PU. The PU may be configured based on a node of an octree.
Information indicating whether to use the LOD for attribute inter-prediction is transmitted to a reception device (or a decoder), and an LOD configurator (1720 in
The LOD configurator 1620 may configure the LOD for each group. In the case of inter-prediction, the LOD of the reference frame may be transmitted to an intra/inter neighbor set configurator 1640.
The PU configurator 1630 may configure an octree node-based attribute PU according to the PU of the geometry. When whether to correct the PU according to attribute information is set, the average attribute information about the PU of the current frame may be compared with the average attribute information about the PU of the reference frame and the nodes (or regions) around the PU to change the PU to the most similar node. Whether to correct the PU according to the attribute information may be transmitted to the reception device (or decoder), and whether to adjust the PU may also be transmitted to the reception device such that the reception device may configure the PU to be the same as in the encoder.
The PU configurator 1630 may configure a PU of the current frame and a matching PU of the reference frame, calculate a PU-specific attribute information change vector, and transmit the calculated change vector to the reception device (or decoder). Information indicating whether to use the PU-specific attribute information change vector may also be transmitted to the reception device (or the decoder). The reception device may predict and restore an attribute value through an attribute inter-information PU predictor (1750 in
The intra/inter neighbor set configurator 1640 may search for a neighbor close to the point as a point for attribute prediction based on the LOD or the PU generated for each group to configure an inter neighbor set and an intra neighbor set. The maximum number of neighbors per point may be set as a user encoding option, and the default number ts may be 3. The search range for the inter neighbor set may be signaled to the decoder and used in configuring the neighbor set.
An attribute information inter-predictor 1650 may predict the attribute information about the current point in the current frame based on the PU points in the reference frame to which the PU-specific attribute information change vector is applied, depending on whether the PU-specific attribute information change vector is used.
The intra/inter neighbor set configurator 1640, the attribute information inter-predictor 1650, or the attribute information intra-predictor may receive the inter neighbor set and the intra neighbor set from the intra/inter neighbor set configurator and select the best predicted value through the RDO. When the best prediction belongs to the inter neighbor set, inter_flag may be set to TRUE and may be transmitted together with the mode to the reception device (or decoder). When the best prediction belongs to the intra neighbor set, inter_flag may be set to FALSE and may be transmitted together with the mode to the reception device (or decoder).
The reception device/method of
Referring to
The reception device according to the embodiments may include an attribute information decoder. The attribute information decoder may include the following elements.
The attribute information decoder may decode information about whether the PU is configured transmitted from the transmission device (or encoder), and an LOD configurator 1720 or a PU configurator 1730 may perform an operation according to whether to configure an LOD.
The LOD configurator 1720 may configure an LOD for each group. In the case of inter-prediction, the LOD of the reference frame may be transmitted to a neighbor set intra/inter configurator 1740.
The PU configurator 1730 may configure an octree node-based attribute information PU corresponding to the PU of the geometry. When whether to correct the PU according to the attribute is set, the average attribute information about the PU of the current frame may be compared with the average attribute information about the PU of the reference frame and the nodes around the PU to change the PU to the most similar node (having the smallest difference). The reception device according to the embodiments may decode information about whether to correct the PU according to the attribute information transmitted from the transmission device (or encoder) and decode information about whether to adjust the PU to reconstruct the PU.
The PU configurator 1730 may configure a PU of the current frame and a matching PU of the reference frame, and then decode a PU-specific attribute information change vector and information indicating whether to use the PU-specific attribute information change vector transmitted from the encoder, and the attribute inter-information PU predictor 1750 may predict or restore the attribute.
The intra/inter neighbor set configurator 1740 may search for a neighbor close to the point as a point for attribute prediction based on the LOD or the PU generated for each group to configure an inter neighbor set and an intra neighbor set. The search range for the inter neighbor set transmitted from the encoder may be decoded and used in configuring the neighbor set.
An attribute information inter-predictor 1750 may predict the attribute information about the current point based on the points belonging to the PU in the reference frame to which the PU-specific attribute information change vector is applied, depending on whether the reconstructed PU-specific attribute information change vector is used.
The attribute information inter-predictor 1750 may receive the inter neighbor set and the intra neighbor set from the intra intra/inter neighbor set configurator 1740, and reconstruct the attribute information by restoring the received inter_flag, mode, and residual value.
According to embodiments, the transmission/reception device/method may signal related information in order to perform attribute information prediction according to embodiments. The signaling information according to the embodiments may be used at the transmitting end or the receiving end.
The encoded point cloud may be configured as described below. A point cloud data encoder that performs geometry encoding and/or attribute encoding may generate an encoded point cloud (or a bitstream containing the point cloud). In addition, signaling information related to the point cloud data may be generated and processed by a metadata processor of the point cloud data transmission device and included in the point cloud as described below.
Each abbreviation means the following. Each abbreviation may be referred to by another term within the scope of the equivalent meaning.
In the attribute information encoding/decoding process, related information for attribute inter-prediction for a point cloud data sequence may be added to and signaled in the SPS or the APS. When there are tiles or slices having different attribute characteristics in the same sequence, the related information for the attribute inter-prediction function for the sequence may be added to and signaled in the TPS or the Attr for each slice.
According to embodiments, the transmission/reception device/method may provide tiles or slices to allow the point cloud to be partitioned into regions for processing.
When the point cloud data is partitioned into regions, an option for generating different sets of neighbor points for the respective regions may be configured to provide a selection method exhibiting low complexity and low reliability of results or a selection method exhibiting high complexity and high reliability. The option may be configured differently depending on the processing capacity of the receiver.
The option may be configured differently because, when the point cloud data is partitioned into regions, the attribute characteristics of a specific region may be different from the attribute characteristics of the sequence.
Therefore, when the point cloud data is divided into tiles, a different maximum range of neighbor points may be applied according to each tile. When the point cloud data is divided into slices, a different maximum range of neighbor points may be applied according to each slice.
PU-related information for attribute inter-prediction may be added to the attribute PU header.
In the attribute information encoding/decoding process, information for attribute inter-prediction may be added to a sequence parameter set and signaled. The added parameters may be efficiently signaled for the neighbor configuration function and inter-prediction. The name of the signaling information may be understood within the scope of the meaning and function of the signaling information.
attr_inter_LOD_generation_flag[i] may indicate whether to configure an LOD in attribute information inter-prediction of the point cloud data sequence. True: LOD applied; False: PU applied.
attr_inter_pu_generation_with_avg_attr_flag[i] indicates whether to readjust the matching PU in the reference frame based on the average attribute value in the matching PUs in the geometry-based current frame and the reference frame when the PUs are configured to perform attribute inter-prediction in compressing the attribute information about a point cloud data sequence.
attr_inter_neighbor_search_range[i] may indicate the point search range for configuring a neighbor set in inter-frame prediction when inter-predicting attribute information about a point cloud data sequence.
profile_idc may indicate a profile to which the bitstream conforms as specified in Annex A. The bitstream does not contain a value of profile_idc other than the values specified in Annex A. The other values of profile fix_idc may be reserved for future use in ISO/IEC.
profile_compatibility_flags equal to 1 indicates that the bitstream conforms to the profile indicated by profile_idc equal to j.
sps_num_attribute_sets may indicate the number of attributes coded in the bitstream. The value of sps_num_attribute_sets shall be in the range of 0 to 63.
attribute_dimension[i] may specify the number of components of the i-th attribute.
attribute_instance_id[i] may specify an instance ID for the i-th attribute.
In the attribute information encoding/decoding process, information for attribute inter-prediction may be added to an attribute parameter set and signaled. The added parameters may be efficiently signaled for the neighbor configuration function and inter-prediction. The name of the signaling information may be understood within the scope of the meaning and function of the signaling information.
attr_inter_LOD_generation_flag[i] may indicate whether to configure an LOD in attribute information inter-prediction of the point cloud data sequence. True: LOD applied; False: PU applied.
attr_inter_pu_generation_with_avg_attr_flag[i] indicates whether to readjust the matching PU in the reference frame based on the average attribute value in the matching PUs in the geometry-based current frame and the reference frame when the PUs are configured to perform attribute inter-prediction in compressing the attribute information about a point cloud data sequence.
attr_inter_neighbor_search_range[i] may indicate the point search range for configuring a neighbor set in inter-frame prediction when inter-predicting attribute information about a point cloud data sequence.
aps_attr parameter_set_id may provide an identifier for the APS for reference by other syntax elements. The value of aps_attr_parameter_set_id is in the range of 0 to 15.
aps_seq_parameter_set_id may specify the value of sps_seq_parameter_set_id for the active SPS. The value of aps_seq_parameter_set_id may be in the range of 0 to 15.
Lifting_num_pred_nearest_neighbours may specify the maximum number of nearest neighbors to be used for prediction. The value of Lifting_num_pred_nearest_neighbours may be in the range of 1 to xx.
lifting_max_num_direct predictors specifies the maximum number of predictor to be used for direct prediction. The value of lifting_max_num_direct_predictors shall be range of 0 to lifting_num_pred_nearest_neighbours. The value of the variable MaxNumPredictors that is used in the decoding process as follows:
Lifting_max_num_direct_predictors may specify the maximum number of predictors to be used for direct prediction. The value of lifting_max_num_direct_predictors may be in the range of 0 to lifting_num_pred_nearest_neighbours. The value of the variable
MaxNumPredictors that is used in the decoding process is as follows:
MaxNumPredictors=lifting_max_num_direct predicots+1
In the attribute information encoding/decoding process, information for attribute inter-prediction may be added to a tile parameter set and signaled. The added parameters may be efficiently signaled for the neighbor configuration function and inter-prediction. The name of the signaling information may be understood within the scope of the meaning and function of the signaling information.
attr_inter_LOD_generation_flag[i] may indicate whether to configure an LOD in attribute information inter-prediction of the point cloud data sequence. True: LOD applied; False: PU applied.
attr_inter_pu_generation_with_avg_attr_flag[i] indicates whether to readjust the matching PU in the reference frame based on the average attribute value in the matching PUs in the geometry-based current frame and the reference frame when the PUs are configured to perform attribute inter-prediction in compressing the attribute information about a point cloud data sequence.
attr_inter_neighbor_search_range[i] may indicate the point search range for configuring a neighbor set in inter-frame prediction when inter-predicting attribute information about a point cloud data sequence.
num_tiles may specify the number of tiles signaled for the bitstream. When not present, num_tiles may be inferred to be 0.
tile_bounding_box_offset_x[i] may indicate the x offset of the i-th tile in the Cartesian coordinates. When not present, the value of tile_bounding_box_offset_x[0] may be inferred to be sps_bounding_box_offset_x.
tile_bounding_box_offset_y[i] may indicate the y offset of the i-th tile in the Cartesian coordinates. When not present, the value of tile_bounding_box_offset_y[0] may be inferred to be sps_bounding_box_offset_y.
In the attribute information encoding/decoding process, information for attribute inter-prediction may be added to an attribute slice header and signaled. The added parameters may be efficiently signaled for the neighbor configuration function and inter-prediction. The name of the signaling information may be understood within the scope of the meaning and function of the signaling information.
attr_inter_LOD_generation_flag[i] may indicate whether to configure an LOD in attribute information inter-prediction of the point cloud data sequence. True: LOD applied; False: PU applied.
attr_inter_pu_generation_with_avg_attr_flag[i] indicates whether to readjust the matching PU in the reference frame based on the average attribute value in the matching PUs in the geometry-based current frame and the reference frame when the PUs are configured to perform attribute inter-prediction in compressing the attribute information about a point cloud data sequence.
attr_inter_neighbor_search_range[i] may indicate the point search range for configuring a neighbor set in inter-frame prediction when inter-predicting attribute information about a point cloud data sequence.
abh_attr parameter_set_id may specify the value of aps_attr_parameter_set_id of the active APS.
abh_attr_sps_attr_idx may specify the attribute set in the active SPS. The value of abh_attr_sps_attr_idx may be in the range of 0 to sps_num_attribute_sets in the active SPS.
ash_attr_geom_slice_id may specify the value of gsh_slice_id in the active geometry slice header.
In the attribute information encoding/decoding process, information for attribute inter-prediction may be added to an Attr PU header and signaled. The added parameters may be efficiently signaled for the neighbor configuration function and inter-prediction. In addition, inter-prediction-related option information may be signaled through the Attr PU header by generating the Attr PU header. Parameters may be efficiently signaled to support inter-prediction. The name of the signaling information may be understood within the scope of the meaning and function of the signaling information.
pu_tile_id may indicate the tile ID to which the PU belongs.
pu_slice_id may indicate the slice ID to which the PU belongs.
pu_cnt may indicate the number of PUs included in a slice.
pu_id may indicate the PU ID.
PU_octree_level indicates the octree level of a PU in generating the PU based on the octree.
PU_Octree_MC indicates the Morton code value at the octree level of a PU in generating the PU based on the octree.
pu_local_motion_vector indicates a local motion vector applied to the PU.
pu_local_attr_vector indicates a local attribute change vector applied to the PU.
pu_local_attr_apply_flag indicates whether an attribute change vector is applied to the PU.
pu_origin_xyz indicates the position of the origin of the entire PUs.
pu_original_log2_scale indicates the origin scale value of the entire PUs.
AttrDim=attribute_dimension_minus1[ash_attr_sps_attr_idx]+1
attribute_dimension_minus1[attrId] plus 1 specifies the number of components of the attrId-th attribute.
The transmission method of
Referring to
The encoding of the point cloud data (S2400) may include encoding geometry and encoding an attribute, wherein the encoding of the attribute may include generating a level of detail (LOD) and predicting the attribute based on the LOD.
The LOD generation may be performed by the LOD configurator 1620 of
In predicting the attribute based on the LOD, the attribute may be predicted based on the LOD of the reference frame. The reference frame may represent a previously processed frame and may be referred to as a previous frame.
When the attribute is not predicted based on the LOD, the transmission method according to the embodiments may include predicting the attribute based on a prediction region (or a PU). Accordingly, the encoding of the attribute may include configuring a prediction region and predicting the attribute based on the prediction region. The prediction region may be referred to as a PU, a prediction zone, a prediction node, a prediction block, or the like, and may represent a unit serving as a reference for prediction.
In predicting the attribute based on the prediction region, the transmission method according to the embodiments may predict the attribute information about the current point by searching for neighbors from regions adjacent to the prediction region to which the current point belongs, and registering the found neighbors in a predictor.
In addition, the transmission method according to the embodiments may include predicting attribute information about the current point by searching for neighbors from a reference prediction region of a previous frame (or a reference frame) corresponding to the prediction region and regions adjacent to the reference prediction region and registering the found neighbors in a predictor. In this case, the average value of the attribute of the points belonging to the prediction region of the current frame may be compared with the average value of the attribute of the points belonging to the reference prediction region and the regions adjacent to the reference prediction region to change the reference prediction region. For example, the reference prediction region may be changed to a region having the smallest difference between the average values. The attribute information that is averaged for comparison may include color and reflectance.
In attribute prediction, the transmission method according to the embodiments may include calculating an attribute change vector based on a difference in the value of the attribute information between the prediction region of the current frame and the reference prediction region of the reference frame. For example, a color change vector may be calculated based on the difference in the value of the color information. Accordingly, the attribute information about the current point may be predicted based on the attribute change vector.
According to embodiments, the bitstream contains information indicating whether to change the reference prediction region based on the average value of the attribute information about the points belonging to the prediction region of the current frame.
A transmission device according to embodiments may include an encoder configured to encode point cloud data and a transmitter configured to transmit a bitstream containing the point cloud data. Each of the operations of the transmission method according to the embodiments may be performed by components such as a processor, a unit, and a module. The components may be referred to by various terms that may represent the functions of the respective operations.
The reception method of
The reception method of
A reception method according to embodiments may include receiving a bitstream containing point cloud data (S2500) and decoding the point cloud data (S2510).
The decoding of the point cloud data (S2510) may include decoding geometry and decoding an attribute, wherein the decoding of the attribute may include generating a level of detail (LOD) and predicting the attribute based on the LOD.
The LOD generation may be performed by the LOD configurator 1720 of
In predicting the attribute based on the LOD, the attribute may be predicted based on the LOD of the reference frame. The reference frame may represent a previously processed frame and may be referred to as a previous frame.
When the attribute is not predicted based on the LOD, the reception method according to the embodiments may include predicting the attribute based on a prediction region (or a PU). Accordingly, the decoding of the attribute may include configuring a prediction region and predicting the attribute based on the prediction region. The prediction region may be referred to as a PU, a prediction zone, a prediction node, a prediction block, or the like, and may represent a unit serving as a reference for prediction.
In predicting the attribute based on the prediction region, the reception method according to the embodiments may predict the attribute information about the current point by searching for neighbors from regions adjacent to the prediction region to which the current point belongs, and registering the found neighbors in a predictor.
In addition, the reception method according to the embodiments may include predicting attribute information about the current point by searching for neighbors from a reference prediction region of a previous frame (or a reference frame) corresponding to the prediction region and regions adjacent to the reference prediction region and registering the found neighbors as predictors. In this case, the average value of the attribute of the points belonging to the prediction region of the current frame may be compared with the average value of the attribute of the points belonging to the reference prediction region and the regions adjacent to the reference prediction region to change the reference prediction region. For example, the reference prediction region may be changed to a region having the smallest difference between the average values. The attribute information that is averaged for comparison may include color and reflectance.
In attribute prediction, the reception method according to the embodiments may include calculating an attribute change vector based on a difference in the value of the attribute information between the prediction region of the current frame and the reference prediction region of the reference frame. For example, a color change vector may be calculated based on the difference in the value of the color information. Accordingly, the attribute information about the current point may be predicted based on the attribute change vector.
According to embodiments, the bitstream contains information indicating whether to change the reference prediction region based on the average value of the attribute information about the points belonging to the prediction region of the current frame.
A reception device according to embodiments may include a receiver configured to receive a bitstream containing point cloud data and a decoder configured to decode the point cloud data. Each of the operations of the reception method according to the embodiments may be performed by components such as a processor, a unit, and a module. The components may be referred to by various terms that may represent the functions of the respective operations.
For efficient compression of point cloud data having multiple frames, inter-prediction coding is a necessary technique. The size of the bitstream may be reduced by analyzing the redundancy and motion of content within frames over time and compressing the frames based on the analysis, rather than compressing every frame with independent inter-prediction coding.
In order to perform the attribute inter-prediction in the G-PCC encoding/decoding process of the above-described embodiments, provided are a neighbor set selection method and an attribute inter-prediction method using an attribute change vector for each PU.
Thus, the present embodiments may improve the attribute compression efficiency by not only performing LOD configuration through the encoder/decoder of geometry-based point cloud compression (G-PCC) for compressing three-dimensional point cloud data, but also by using or correcting the PU of the geometry without the LOD configuration to find a neighbor set through intra/inter-prediction and select the best predicted value through RDO.
Methods/devices (a transmission method/device and/or a reception method/device) according to embodiments may efficiently encode/decode point cloud data by using PU-specific attribute change vectors to efficiently deal with the phenomenon of a global change in color at the same point depending on the surrounding environment.
The point cloud data transmission/reception device (e.g., the neighbor set generator) according to the above-described embodiments may increase the attribute compression/decompression efficiency with an optimal neighbor set through neighbor set configuration and use of an attribute change vector for each PU (or prediction region), and/or related signaling.
Accordingly, the present embodiments may provide an efficient attribute bitstream for providing inter-prediction coding of an encoder/decoder of geometry-based point cloud compression (G-PCC) for compressing three-dimensional point cloud data, thereby enabling efficient encoding/decoding of point cloud data.
Therefore, as described above, based on the attribute inter-prediction method and/or related signaling information according to embodiments, the transmission/reception method/device according to embodiments may efficiently compress data contained in frames over time to reduce the size of the bitstream. Further, the method/device according to the embodiments may quickly and accurately reconstruct and present the point cloud data to a user.
A process of the transmitting/reception device according to the above-described embodiments may be described in combination with the following point cloud compression processing. The operations according to the embodiments described in the present disclosure may be performed by a transmission/reception device including a memory and/or a processor according to embodiments. The memory may store programs for processing/controlling operations according to embodiments, and the processor may control various operations described in the present disclosure. The processor may be referred to as a controller or the like. The operations may be performed by firmware, software, and/or a combination thereof. The firmware, software, and/or a combination thereof may be stored in the processor or the memory.
Embodiments have been described from the method and/or device perspective, and descriptions of methods and devices may be applied so as to complement each other.
Although the accompanying drawings have been described separately for simplicity, it is possible to design new embodiments by merging the embodiments illustrated in the respective drawings. Designing a recording medium readable by a computer on which programs for executing the above-described embodiments are recorded as needed by those skilled in the art also falls within the scope of the appended claims and their equivalents. The devices and methods according to embodiments may not be limited by the configurations and methods of the embodiments described above. Various modifications can be made to the embodiments by selectively combining all or some of the embodiments. Although preferred embodiments have been described with reference to the drawings, those skilled in the art will appreciate that various modifications and variations may be made in the embodiments without departing from the spirit or scope of the disclosure described in the appended claims. Such modifications are not to be understood individually from the technical idea or perspective of the embodiments.
Various elements of the devices of the embodiments may be implemented by hardware, software, firmware, or a combination thereof. Various elements in the embodiments may be implemented by a single chip, for example, a single hardware circuit. According to embodiments, the components according to the embodiments may be implemented as separate chips, respectively. According to embodiments, at least one or more of the components of the device according to the embodiments may include one or more processors capable of executing one or more programs. The one or more programs may perform any one or more of the operations/methods according to the embodiments or include instructions for performing the same.
Executable instructions for performing the method/operations of the device according to the embodiments may be stored in a non-transitory CRM or other computer program products configured to be executed by one or more processors, or may be stored in a transitory CRM or other computer program products configured to be executed by one or more processors.
In addition, the memory according to the embodiments may be used as a concept covering not only volatile memories (e.g., RAM) but also nonvolatile memories, flash memories, and PROMs. In addition, it may also be implemented in the form of a carrier wave, such as transmission over the Internet. In addition, the processor-readable recording medium may be distributed to computer systems connected over a network such that the processor-readable code may be stored and executed in a distributed fashion.
In this specification, the term “/” and “,” should be interpreted as indicating “and/or.” For instance, the expression “A/B” may mean “A and/or B.” Further, “A, B” may mean “A and/or B.” Further, “A/B/C” may mean “at least one of A, B, and/or C.” Also, “A/B/C” may mean “at least one of A, B, and/or C.” Further, in this specification, the term “or” should be interpreted as indicating “and/or.” For instance, the expression “A or B” may mean 1) only A, 2) only B, or 3) both A and B. In other words, the term “or” used in this document should be interpreted as indicating “additionally or alternatively.”
Terms such as first and second may be used to describe various elements of the embodiments. However, various components according to the embodiments should not be limited by the above terms. These terms are only used to distinguish one element from another. For example, a first user input signal may be referred to as a second user input signal. Similarly, the second user input signal may be referred to as a first user input signal. Use of these terms should be construed as not departing from the scope of the various embodiments. The first user input signal and the second user input signal are both user input signals, but do not mean the same user input signals unless context clearly dictates otherwise.
The terms used to describe the embodiments are used for the purpose of describing specific embodiments, and are not intended to limit the embodiments. As used in the description of the embodiments and in the claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. The expression “and/or” is used to include all possible combinations of terms. The terms such as “includes” or “has” are intended to indicate existence of figures, numbers, steps, elements, and/or components and should be understood as not precluding possibility of existence of additional existence of figures, numbers, steps, elements, and/or components. As used herein, conditional expressions such as “if” and “when” are not limited to an optional case and are intended to be interpreted, when a specific condition is satisfied, to perform the related operation or interpret the related definition according to the specific condition.
Operations according to the embodiments described in this specification may be performed by a transmission/reception device including a memory and/or a processor according to embodiments. The memory may store programs for processing/controlling the operations according to the embodiments, and the processor may control various operations described in this specification. The processor may be referred to as a controller or the like. In embodiments, operations may be performed by firmware, software, and/or a combination thereof. The firmware, software, and/or a combination thereof may be stored in the processor or the memory.
The operations according to the above-described embodiments may be performed by the transmission device and/or the reception device according to the embodiments. The transmission/reception device may include a transmitter/receiver configured to transmit and receive media data, a memory configured to store instructions (program code, algorithms, flowcharts and/or data) for a process according to embodiments, and a processor configured to control operations of the transmission/reception device.
The processor may be referred to as a controller or the like, and may correspond to, for example, hardware, software, and/or a combination thereof. The operations according to the above-described embodiments may be performed by the processor. In addition, the processor may be implemented as an encoder/decoder for the operations of the above-described embodiments.
As described above, related details have been described in the best mode for carrying out the embodiments.
As described above, the embodiments are fully or partially applicable to a point cloud data transmission/reception device and system. Those skilled in the art may change or modify the embodiments in various ways within the scope of the embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0154736 | Nov 2021 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2022/017777 | 11/11/2022 | WO |
