Encoding device, decoding device, encoding method, and decoding method

Abstract

An encoding device (100) is provided with: a memory (152); and a circuit (151) that can access the memory (152). In operation, the circuit (151) encodes displacement data used for deriving a displacement vector for each of a plurality of vertices included in a three-dimensional mesh, wherein the displacement vector indicates displacement of each vertex from a first position, generated by using a base mesh, the plurality of vertices include a first vertex, a second vertex, and a third vertex, and the displacement data of the first vertex indicates the difference between the displacement vector of the first vertex and a composite vector obtained by combining the displacement vector of the second vertex and the displacement vector of the third vertex.

Description

Encoding device, decoding device, encoding method, and decoding method

[0001] The present disclosure relates to an encoding device and the like.

[0002] In US Pat. No. 6,299,549 a method and apparatus for encoding and decoding three-dimensional mesh data is proposed.

[0003] Japanese Patent Application Laid-Open No. 2006-187015

[0004] Further improvements are desired in the encoding or decoding process for three-dimensional data. The present disclosure aims to improve the encoding or decoding process for three-dimensional data.

[0005] An encoding device according to one aspect of the present disclosure comprises a memory and a circuit capable of accessing the memory, and in operation, the circuit encodes displacement data used to derive a displacement vector for each of a plurality of vertices included in a three-dimensional mesh, the displacement vector indicating the displacement of each vertex from a first position generated using a base mesh, the plurality of vertices including a first vertex, a second vertex, and a third vertex, and the displacement data of the first vertex indicating the difference between the displacement vector of the first vertex and a composite vector obtained by combining the displacement vector of the second vertex and the displacement vector of the third vertex.

[0006] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0007] The present disclosure may contribute to improvements in encoding processes and the like related to three-dimensional data.

[0008] 1 is a conceptual diagram showing a three-dimensional mesh according to an embodiment. FIG. 2 is a conceptual diagram showing basic elements of a three-dimensional mesh according to an embodiment. FIG. 3 is a conceptual diagram showing mapping according to an embodiment. FIG. 4 is a block diagram showing a configuration example of an encoding / decoding system according to an embodiment. FIG. 5 is a block diagram showing a configuration example of an encoding device according to an embodiment. FIG. 6 is a block diagram showing another configuration example of an encoding device according to an embodiment. FIG. 7 is a block diagram showing another configuration example of a decoding device according to an embodiment. FIG. 8 is a block diagram showing another configuration example of a decoding device according to an embodiment. FIG. 9 is a block diagram showing another configuration example of a decoding device according to an embodiment. FIG. 10 is a conceptual diagram showing another configuration example of a bit stream according to an embodiment. FIG. 11 is a conceptual diagram showing yet another configuration example of a bit stream according to an embodiment. FIG. 12 is a block diagram showing a specific example of an encoding / decoding system according to an embodiment. FIG. 13 is a conceptual diagram showing an example configuration of point cloud data according to an embodiment. FIG. 14 is a conceptual diagram showing an example data file of point cloud data according to an embodiment. FIG. 15 is a conceptual diagram showing an example configuration of mesh data according to an embodiment. FIG. 16 is a conceptual diagram showing an example data file of mesh data according to an embodiment. FIG. 17 is a conceptual diagram showing types of three-dimensional data according to an embodiment. FIG. 18 is a block diagram showing an example configuration of a three-dimensional data encoder according to an embodiment. FIG. 19 is a block diagram showing an example configuration of a three-dimensional data decoder according to an embodiment. FIG. 19 is a block diagram showing another configuration example of a three-dimensional data encoder according to an embodiment. FIG. 19 is a block diagram showing another configuration example of a three-dimensional data decoder according to an embodiment. FIG. 1 is a conceptual diagram showing a specific example of encoding processing according to an embodiment. FIG. 2 is a conceptual diagram showing a specific example of decoding processing according to an embodiment. FIG. 3 is a block diagram showing an implementation example of an encoding device according to an embodiment. FIG. 4 is a block diagram showing an implementation example of a decoding device according to an embodiment. FIG. 5 is a block diagram showing another configuration example of an encoding / decoding system according to an embodiment. FIG. 6 is a block diagram showing another configuration example of an encoding device according to an embodiment. FIG. 7 is a block diagram showing another configuration example of a decoding device according to an embodiment. FIG. 8 is a block diagram showing a detailed configuration example of an encoding device according to an embodiment. FIG. 9 is a block diagram showing a modified example of the detailed configuration of an encoding device according to an embodiment. FIG. 10 is a flow diagram showing processing of an encoding device according to an embodiment. FIG. 11 is an explanatory diagram conceptually showing encoding of a mesh frame according to an embodiment.1 is a block diagram showing a detailed configuration example of a decoding device according to an embodiment; FIG. 2 is a block diagram showing a modified example of the detailed configuration of a decoding device according to an embodiment; FIG. 3 is a flow diagram showing processing by a decoding device according to an embodiment; FIG. 4 is an explanatory diagram conceptually showing decoding of a mesh frame according to an embodiment; FIG. 5 is an explanatory diagram showing an example of subdivision according to an embodiment; FIG. 6 is an explanatory diagram showing an example of displacement of vertices after displacement after subdivision according to an embodiment; FIG. 7 is an explanatory diagram showing example vertices of an original mesh according to an embodiment; FIG. 8 is an explanatory diagram showing an example of a mesh according to an embodiment; FIG. 9 is an explanatory diagram showing an example of division of a mesh into sub-meshes according to an embodiment; FIG. 10 is an explanatory diagram showing a first example of packing of displacement information into an image frame according to an embodiment; FIG. 11 is an explanatory diagram showing a second example of packing of displacement information into an image frame according to an embodiment; FIG. 12 is an explanatory diagram showing a third example of packing of displacement information into an image frame according to an embodiment; FIG. 13 is a flow diagram showing an example of detailed processing by an encoding device according to an embodiment; FIG. 14 is a flow diagram showing an example of detailed processing by a decoding device according to an embodiment; FIG. 15 is an explanatory diagram showing a process of reconstructing a second vertex according to an embodiment; FIG. 16 is an explanatory diagram showing a first example of a process of calculating a third vertex according to an embodiment; FIG. 17 is an explanatory diagram showing a first example of a storage location of parameters according to an embodiment; FIG. 18 is an explanatory diagram showing a second example of a storage location of parameters according to an embodiment. FIG. 10 is an explanatory diagram showing a second example of a calculation process for a third vertex according to an embodiment; FIG. 11 is an explanatory diagram showing a first example of an interpolation process according to an embodiment; FIG. 12 is an explanatory diagram showing a second example of an interpolation process according to an embodiment; FIG. 13 is an explanatory diagram showing a reconstruction process for a fourth vertex according to an embodiment; FIG. 14 is an explanatory diagram showing an example of a reconstructed mesh frame according to an embodiment; FIG. 15 is an explanatory diagram showing a third example of an interpolation process according to an embodiment; and FIG. 16 is an explanatory diagram showing a fourth example of an interpolation process according to an embodiment.

[0009] Introduction Three-dimensional (3D) meshes are used in computer graphics images, which may be composed of multiple temporally distinct frames, each of which may be represented by a 3D mesh.

[0010] A 3D mesh is composed of vertex information indicating the positions of each of the vertices in 3D space, connectivity information indicating the connections between the vertices, and attribute information indicating the attributes of each vertex or face. Each face is constructed according to the connectivity between the vertices. Various computer graphics images can be expressed using such 3D meshes.

[0011] Furthermore, for transmission and storage of the 3D mesh, efficient encoding and decoding of the 3D mesh is expected. For efficient encoding and decoding of the 3D mesh, arithmetic coding and decoding may be used.

[0012] Further improvements are desired in the encoding or decoding process for three-dimensional data. The present disclosure aims to improve the encoding or decoding process for three-dimensional data.

[0013] Below, examples of inventions that can be obtained from the disclosure of this specification will be given, and the effects and the like that can be obtained from these inventions will be explained.

[0014] (1) An encoding device comprising a memory and a circuit accessible to the memory, wherein the circuit, in operation, encodes displacement data used to derive a displacement vector for each of a plurality of vertices included in a three-dimensional mesh, the displacement vector indicating the displacement of each vertex from a first position generated using a base mesh, the plurality of vertices including a first vertex, a second vertex, and a third vertex, and the displacement data of the first vertex indicating the difference between the displacement vector of the first vertex and a composite vector obtained by combining the displacement vector of the second vertex and the displacement vector of the third vertex.

[0015] According to the above aspect, the encoding device may be able to reduce the amount of information in the displacement data of the first vertex because the displacement data of the first vertex indicates the difference between the displacement vector of the first vertex, the displacement vector of the second vertex, and the displacement vector of the third vertex. As a result, the encoding device may contribute to reducing the amount of encoded information and improve the efficiency of the encoding or decoding process. In this way, the encoding device may improve the encoding or decoding process for three-dimensional data.

[0016] (2) The encoding device described in (1), wherein the circuit generates the composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with equal weighting, and encodes the displacement data of the first vertex using the generated composite vector.

[0017] According to the above aspect, the encoding device can generate a composite vector by performing an easier calculation process by combining the displacement vector of the second vertex and the displacement vector of the third vertex with equal weighting, thereby contributing to reducing the processing load or power consumption, and thus improving the encoding or decoding process for three-dimensional data.

[0018] (3) The encoding device described in (1), wherein the circuit generates the composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with different weights, and encodes the displacement data of the first vertex using the generated composite vector.

[0019] According to the above aspect, the encoding device may be able to more appropriately generate a composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with different weights. For example, the weights of the displacement vector of the second vertex and the displacement vector of the third vertex may be appropriately set according to the parameters of the encoding process. In this case, the composite vector may be appropriately generated according to the parameters of the encoding process, which may contribute to improving the encoding or decoding process. Therefore, the encoding device may be able to improve the encoding or decoding process for three-dimensional data.

[0020] (4) The encoding device described in (1), wherein the composite vector is generated by weighting and combining multiple displacement vectors including the displacement vector of the second vertex and the displacement vector of the third vertex, and the sum of the weights is 1.

[0021] According to the above aspect, the encoding device may be able to more easily reduce the amount of information in the displacement data of the first vertex by using a reference point set on the line segment connecting the second vertex and the third vertex, thereby improving the encoding or decoding process for three-dimensional data.

[0022] (5) The encoding device described in (1), wherein the composite vector is generated by weighting and combining multiple displacement vectors including the displacement vector of the second vertex and the displacement vector of the third vertex, and the sum of the weights is not 1.

[0023] According to the above aspect, the encoding device may be able to reduce the amount of information in the displacement data of the first vertex by using a reference point that is not on the line segment connecting the second vertex and the third vertex, thereby improving the encoding or decoding process for three-dimensional data.

[0024] (6) A decoding device comprising a memory and a circuit capable of accessing the memory, wherein the circuit, in operation, decodes displacement data used to derive a displacement vector for each of a plurality of vertices included in a three-dimensional mesh, the displacement vector indicating the displacement of each vertex from a first position generated using a base mesh, the plurality of vertices including a first vertex, a second vertex, and a third vertex, and generates the displacement vector of the first vertex using a composite vector obtained by combining the displacement data of the first vertex, the displacement vector of the second vertex, and the displacement vector of the third vertex.

[0025] According to the above aspect, the decoding device may be able to reduce the amount of information in the displacement data of the first vertex because the displacement data of the first vertex indicates the difference between the composite vector obtained by combining the displacement vector of the first vertex, the displacement vector of the second vertex, and the displacement vector of the third vertex. As a result, the decoding device may contribute to reducing the amount of encoded information and improve the efficiency of the encoding or decoding process. In this way, the encoding device may improve the encoding or decoding process for three-dimensional data.

[0026] (7) The decoding device described in (6), wherein the circuit generates the composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with equal weighting, and encodes the displacement data of the first vertex using the generated composite vector.

[0027] According to the above aspect, the decoding device can generate a composite vector by performing an easier calculation process by combining the displacement vector of the second vertex and the displacement vector of the third vertex with equal weighting, thereby contributing to reducing the processing load or power consumption, and thus improving the encoding or decoding process for three-dimensional data.

[0028] (8) The decoding device described in (6), wherein the circuit generates the composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with different weights, and encodes the displacement data of the first vertex using the generated composite vector.

[0029] According to the above aspect, the decoding device may be able to more appropriately generate a composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with different weights. For example, the weights of the displacement vector of the second vertex and the displacement vector of the third vertex may be appropriately set according to the parameters of the encoding process. In this case, the composite vector may be appropriately generated according to the parameters of the encoding process, which may contribute to improving the encoding or decoding process. Therefore, the decoding device may be able to improve the encoding or decoding process for three-dimensional data.

[0030] (9) The decoding device described in (6), wherein the composite vector is generated by weighting and combining multiple displacement vectors including the displacement vector of the second vertex and the displacement vector of the third vertex, and the sum of the weights is 1.

[0031] According to the above aspect, the decoding device may be able to more easily reduce the amount of information in the displacement data of the first vertex by using a reference point set on the line segment connecting the second vertex and the third vertex, thereby improving the encoding or decoding process for three-dimensional data.

[0032] (10) The decoding device described in (6), wherein the composite vector is generated by weighting and combining multiple displacement vectors including the displacement vector of the second vertex and the displacement vector of the third vertex, and the sum of the weights is not 1.

[0033] According to the above aspect, the decoding device may be able to reduce the amount of information in the displacement data of the first vertex by using a reference point that is not on the line segment connecting the second vertex and the third vertex, thereby improving the encoding or decoding process for three-dimensional data.

[0034] (11) An encoding method in which displacement data used to derive a displacement vector (AP, BQ, YR) for each of a plurality of vertices (P, Q, R) included in a three-dimensional mesh is encoded, the displacement vector indicating the displacement of each vertex from a first position (A, B, Y) generated using a base mesh, the plurality of vertices including a first vertex (R), a second vertex (P), and a third vertex (Q), and the displacement data of the first vertex indicates the difference between the displacement vector of the first vertex and a composite vector obtained by combining the displacement vector of the second vertex and the displacement vector of the third vertex.

[0035] According to the above aspect, the same effects as those of the encoding device can be achieved.

[0036] (12) A decoding method that decodes displacement data used to derive a displacement vector (AP, BQ, YR) for each of a plurality of vertices (P, Q, R) included in a three-dimensional mesh, the displacement vector indicating the displacement of each vertex from a first position (A, B, Y) generated using a base mesh, the plurality of vertices including a first vertex (R), a second vertex (P), and a third vertex (Q), and generates the displacement vector of the first vertex using a composite vector obtained by combining the displacement data of the first vertex, the displacement vector of the second vertex, and the displacement vector of the third vertex.

[0037] According to the above aspect, the same effects as those of the above decoding device can be achieved.

[0038] Furthermore, these comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0039] <Expressions and Terms> The following expressions and terms are used herein.

[0040] (1) Three-dimensional Mesh A three-dimensional mesh is a collection of multiple faces, and represents, for example, a three-dimensional object. A three-dimensional mesh is mainly composed of vertex information, connectivity information, and attribute information. A three-dimensional mesh may be expressed as a polygon mesh or a mesh. A three-dimensional mesh may also vary over time. A three-dimensional mesh may include metadata related to the vertex information, connectivity information, and attribute information, and may also include other additional information.

[0041] (2) Vertex Information Vertex information is information indicating a vertex. For example, the vertex information indicates the position of a vertex in a three-dimensional space. Furthermore, a vertex corresponds to a vertex of a face that constitutes a three-dimensional mesh. Vertex information may be expressed as "geometry." Furthermore, vertex information may be expressed as position information.

[0042] (3) Connection Information Connection information is information that indicates connections between vertices. For example, connection information indicates connections for forming faces or edges of a three-dimensional mesh. Connection information may be expressed as "Connectivity." Connection information may also be expressed as face information.

[0043] (4) Attribute Information Attribute information is information that indicates attributes of a vertex or a face. For example, attribute information indicates attributes such as a color, an image, and a normal vector associated with a vertex or a face. Attribute information may be expressed as "texture."

[0044] (5) Faces A face is an element that constitutes a three-dimensional mesh. Specifically, a face is a polygon on a plane in three-dimensional space. For example, a face can be defined as a triangle in three-dimensional space.

[0045] (6) Plane A plane is a two-dimensional plane in a three-dimensional space. For example, a polygon is formed on a plane, and multiple polygons are formed on multiple planes.

[0046] (7) Bitstream: A bitstream corresponds to coded information. A bitstream may also be referred to as a stream, a coded bitstream, a compressed bitstream, or a coded signal.

[0047] (8) Encoding and Decoding The term encoding may be substituted with terms such as storing, including, writing, describing, signaling, sending, notifying, saving, or compressing, and these terms may be interchangeable. For example, encoding information may mean including the information in a bitstream. Also, encoding information into a bitstream may mean encoding the information to generate a bitstream that includes the encoded information.

[0048] Additionally, the term "decode" may be replaced with terms such as "read," "decode," "read," "load," "derive," "obtain," "receive," "extract," "reconstruct," "reconstruct," "decompress," or "decompress," and these terms may be interchangeable. For example, decoding information may mean obtaining information from a bitstream. Decoding information from a bitstream may mean decoding the bitstream to obtain information contained in the bitstream.

[0049] (9) Ordinal Numbers In the description, ordinal numbers such as first and second may be assigned to components, etc. These ordinal numbers may be changed as appropriate. Furthermore, new ordinal numbers may be assigned to components, etc., or removed. Furthermore, these ordinal numbers may be assigned to elements in order to identify them, and may not correspond to a meaningful order.

[0050] <Three-dimensional mesh> Fig. 1 is a conceptual diagram showing a three-dimensional mesh according to this embodiment. A three-dimensional mesh is composed of multiple faces. For example, each face is a triangle. The vertices of these triangles are defined in three-dimensional space. The three-dimensional mesh then represents a three-dimensional object. Each face may have a color or an image.

[0051] FIG. 2 is a conceptual diagram showing the basic elements of a three-dimensional mesh according to this embodiment. A three-dimensional mesh is composed of vertex information, connection information, and attribute information. The vertex information indicates the positions of the vertices of a face in three-dimensional space. The connection information indicates the connections between the vertices. A face can be identified by the vertex information and connection information. In other words, a colorless three-dimensional object is formed in three-dimensional space by the vertex information and connection information.

[0052] The attribute information may be associated with a vertex or a face. The attribute information associated with a vertex may be expressed as "Attribute Per Point." The attribute information associated with a vertex may indicate an attribute of the vertex itself, or may indicate an attribute of a face connected to the vertex.

[0053] For example, a color may be associated with a vertex as attribute information. The color associated with a vertex may be the color of the vertex itself, or the color of a face connected to the vertex. The color of a face may be the average of multiple colors associated with multiple vertices of the face. Furthermore, a normal vector may be associated with a vertex or a face as attribute information. Such a normal vector can represent the front and back of a face.

[0054] A two-dimensional image may be associated with a surface as attribute information. The two-dimensional image associated with a surface is also expressed as a texture image or an "Attribute Map." Information indicating mapping between the surface and the two-dimensional image may be associated with the surface as attribute information. Information indicating such mapping may be expressed as mapping information, vertex information of a texture image, texture coordinates, or "Attribute UV Coordinate."

[0055] Furthermore, information such as color, image, and moving image used as attribute information may be expressed as "parametric space."

[0056] The attribute information allows texture to be reflected on the three-dimensional object. That is, a three-dimensional object having color is formed in three-dimensional space based on the vertex information, connection information, and attribute information.

[0057] In the above, the attribute information is associated with the vertices or faces, but it may also be associated with the edges.

[0058] 3 is a conceptual diagram illustrating mapping according to this embodiment. For example, a region of a two-dimensional image on a two-dimensional plane can be mapped onto a surface of a three-dimensional mesh in three-dimensional space. Specifically, coordinate information of the region in the two-dimensional image is associated with the surface of the three-dimensional mesh. As a result, an image of the mapped region in the two-dimensional image is reflected on the surface of the three-dimensional mesh.

[0059] By using the mapping, the 2D image used as attribute information can be separated from the 3D mesh. For example, in encoding the 3D mesh, the 2D image may be encoded by an image encoding method or a video encoding method.

[0060] <System Configuration> Fig. 4 is a block diagram showing an example of the configuration of a coding / decoding system according to this embodiment. In Fig. 4, the coding / decoding system includes a coding device 100 and a decoding device 200.

[0061] For example, the encoding device 100 obtains a three-dimensional mesh and encodes the three-dimensional mesh into a bitstream. Then, the encoding device 100 outputs the bitstream to the network 300. For example, the bitstream includes the encoded three-dimensional mesh and control information for decoding the encoded three-dimensional mesh. By encoding the three-dimensional mesh, information about the three-dimensional mesh is compressed.

[0062] The network 300 transmits a bitstream from the encoding device 100 to the decoding device 200. The network 300 may be the Internet, a wide area network (WAN), a local area network (LAN), or a combination of these. The network 300 is not necessarily limited to bidirectional communication, and may be a unidirectional communication network for terrestrial digital broadcasting, satellite broadcasting, or the like.

[0063] Furthermore, the network 300 can be replaced by a recording medium such as a DVD (Digital Versatile Disc) or a BD (Blu-Ray Disc (registered trademark)).

[0064] The decoding device 200 obtains a bitstream and decodes a three-dimensional mesh from the bitstream. By decoding the three-dimensional mesh, information about the three-dimensional mesh is expanded. For example, the decoding device 200 decodes the three-dimensional mesh according to a decoding method corresponding to the encoding method used by the encoding device 100 to encode the three-dimensional mesh. That is, the encoding device 100 and the decoding device 200 perform encoding and decoding according to encoding methods and decoding methods that correspond to each other.

[0065] The 3D mesh before encoding may also be referred to as an original 3D mesh, and the 3D mesh after decoding may also be referred to as a reconstructed 3D mesh.

[0066] 5 is a block diagram showing an example of the configuration of a coding device 100 according to this embodiment. For example, the coding device 100 includes a vertex information encoder 101, a connection information encoder 102, and an attribute information encoder 103.

[0067] The vertex information encoder 101 is an electrical circuit that encodes vertex information. For example, the vertex information encoder 101 encodes the vertex information into a bitstream according to a format defined for the vertex information.

[0068] The connection information encoder 102 is an electrical circuit that encodes the connection information, for example, the connection information encoder 102 encodes the connection information into a bitstream according to a format defined for the connection information.

[0069] The attribute information encoder 103 is an electric circuit that encodes the attribute information. For example, the attribute information encoder 103 encodes the attribute information into a bit stream in accordance with a format defined for the attribute information.

[0070] The vertex information, connectivity information, and attribute information may be coded using variable-length coding or fixed-length coding, such as Huffman coding or context-adaptive binary arithmetic coding (CABAC).

[0071] The vertex information encoder 101, the connection information encoder 102, and the attribute information encoder 103 may be integrated together, or each of the vertex information encoder 101, the connection information encoder 102, and the attribute information encoder 103 may be further subdivided into multiple components.

[0072] 6 is a block diagram showing another example of the configuration of the encoding device 100 according to this embodiment. For example, the encoding device 100 includes a pre-processor 104 and a post-processor 105 in addition to the configuration shown in FIG.

[0073] The preprocessor 104 is an electrical circuit that performs processing before encoding the vertex information, connectivity information, and attribute information. For example, the preprocessor 104 may perform a conversion process, a separation process, a multiplexing process, or the like on the 3D mesh before encoding. More specifically, for example, the preprocessor 104 may separate the vertex information, connectivity information, and attribute information from the 3D mesh before encoding.

[0074] The post-processor 105 is an electrical circuit that performs processing after the vertex information, connection information, and attribute information are encoded. For example, the post-processor 105 may perform conversion processing, separation processing, multiplexing processing, or the like on the encoded vertex information, connection information, and attribute information. More specifically, for example, the post-processor 105 may multiplex the encoded vertex information, connection information, and attribute information into a bitstream. Furthermore, for example, the post-processor 105 may further perform variable-length coding on the encoded vertex information, connection information, and attribute information.

[0075] 7 is a block diagram showing an example of the configuration of a decoding device 200 according to this embodiment. For example, the decoding device 200 includes a vertex information decoder 201, a connection information decoder 202, and an attribute information decoder 203.

[0076] The vertex information decoder 201 is an electrical circuit that decodes vertex information. For example, the vertex information decoder 201 decodes vertex information from a bitstream according to a format defined for the vertex information.

[0077] The connection information decoder 202 is an electrical circuit that decodes the connection information, for example, the connection information decoder 202 decodes the connection information from the bitstream according to a format defined for the connection information.

[0078] The attribute information decoder 203 is an electric circuit that decodes the attribute information. For example, the attribute information decoder 203 decodes the attribute information from the bitstream in accordance with a format defined for the attribute information.

[0079] The vertex information, connection information, and attribute information may be decoded using variable length decoding or fixed length decoding, which may correspond to Huffman coding, context-adaptive binary arithmetic coding (CABAC), or the like.

[0080] The vertex information decoder 201, the connection information decoder 202, and the attribute information decoder 203 may be integrated together, or each of the vertex information decoder 201, the connection information decoder 202, and the attribute information decoder 203 may be further subdivided into multiple components.

[0081] 8 is a block diagram showing another example of the configuration of the decoding device 200 according to this embodiment. For example, the decoding device 200 includes a pre-processor 204 and a post-processor 205 in addition to the configuration shown in FIG.

[0082] The preprocessor 204 is an electrical circuit that performs processing before decoding the vertex information, connection information, and attribute information. For example, the preprocessor 204 may perform conversion processing, separation processing, multiplexing processing, or the like on the bitstream before decoding the vertex information, connection information, and attribute information.

[0083] More specifically, for example, the preprocessor 204 may separate a sub-bitstream corresponding to vertex information, a sub-bitstream corresponding to connectivity information, and a sub-bitstream corresponding to attribute information from the bitstream. Also, for example, the preprocessor 204 may perform variable-length decoding on the bitstream in advance before decoding the vertex information, connectivity information, and attribute information.

[0084] The post-processor 205 is an electrical circuit that performs processing after the vertex information, connection information, and attribute information are decoded. For example, the post-processor 205 may perform conversion processing, separation processing, multiplexing processing, or the like on the decoded vertex information, connection information, and attribute information. More specifically, for example, the post-processor 205 may multiplex the decoded vertex information, connection information, and attribute information onto a three-dimensional mesh.

[0085] <Bitstream> Vertex information, connection information, and attribute information are coded and stored in a bitstream. The relationship between this information and the bitstream is shown below.

[0086] 9 is a conceptual diagram showing an example of the configuration of a bitstream according to this embodiment. In this example, connection information, vertex information, and attribute information are integrated in the bitstream. For example, the connection information, vertex information, and attribute information may be included in a single file.

[0087] Furthermore, multiple portions of this information may be stored sequentially, such as a first portion of connection information, a first portion of vertex information, a first portion of attribute information, a second portion of connection information, a second portion of vertex information, a second portion of attribute information, etc. These multiple portions may correspond to multiple portions that are different in time, multiple portions that are different in space, or multiple different faces.

[0088] Furthermore, the storage order of the connection information, vertex information, and attribute information is not limited to the above example, and a storage order different from the above example may be used.

[0089] 10 is a conceptual diagram showing another example of the configuration of a bitstream according to this embodiment. In this example, a plurality of files are included in the bitstream, and connection information, vertex information, and attribute information are stored in different files. Here, a file containing connection information, a file containing vertex information, and a file containing attribute information are shown, but the storage format is not limited to this example. For example, two types of information among the connection information, vertex information, and attribute information may be included in one file, and the remaining type of information may be included in another file.

[0090] Alternatively, the information may be split and stored in more files. For example, multiple pieces of connectivity information may be stored in multiple files, multiple pieces of vertex information may be stored in multiple files, or multiple pieces of attribute information may be stored in multiple files. These multiple pieces may correspond to multiple temporally different pieces, multiple spatially different pieces, or multiple different faces.

[0091] Furthermore, the storage order of the connection information, vertex information, and attribute information is not limited to the above example, and a storage order different from the above example may be used.

[0092] 11 is a conceptual diagram showing another example of the configuration of a bitstream according to this embodiment. In this example, the bitstream is composed of multiple separable sub-bitstreams, and connection information, vertex information, and attribute information are stored in different sub-bitstreams.

[0093] Here, a sub-bitstream containing connection information, a sub-bitstream containing vertex information, and a sub-bitstream containing attribute information are shown, but the storage format is not limited to this example.

[0094] For example, two types of information among the connection information, vertex information, and attribute information may be included in one sub-bitstream, and the remaining type of information may be included in another sub-bitstream. Specifically, attribute information of a two-dimensional image or the like may be stored in a sub-bitstream that complies with an image coding method, separate from the sub-bitstreams of the connection information and vertex information.

[0095] Also, each sub-bitstream may include multiple files, and multiple pieces of connectivity information may be stored in multiple files, multiple pieces of vertex information may be stored in multiple files, or multiple pieces of attribute information may be stored in multiple files.

[0096] 9, 10, and 11, and a storage order different from the above examples may be used. For example, the vertex information, connection information, and attribute information may be stored in the bitstream in this order. Alternatively, the connection information, connection information, and attribute information may be stored in the bitstream in any of the following orders: connection information, attribute information, and vertex information; vertex information, attribute information, and connection information; attribute information, connection information, and vertex information; or attribute information, vertex information, and connection information.

[0097] Furthermore, each of the connection information, vertex information, and attribute information may be divided into a plurality of data, and the plurality of data may be stored in a cyclical or random order within the bitstream.

[0098] 12 is a block diagram showing a specific example of an encoding / decoding system according to this embodiment. In FIG. 12, the encoding / decoding system includes a three-dimensional data encoding system 110, a three-dimensional data decoding system 210, and an external connector 310.

[0099] The three-dimensional data encoding system 110 includes a controller 111, an input / output processor 112, a three-dimensional data encoder 113, a three-dimensional data generator 115, and a system multiplexer 114. The three-dimensional data decoding system 210 includes a controller 211, an input / output processor 212, a three-dimensional data decoder 213, a system demultiplexer 214, a presenter 215, and a user interface 216.

[0100] In the three-dimensional data encoding system 110, sensor data is input from a sensor terminal to a three-dimensional data generator 115. The three-dimensional data generator 115 generates three-dimensional data, such as point cloud data or mesh data, from the sensor data and inputs it to a three-dimensional data encoder 113.

[0101] For example, the three-dimensional data generator 115 generates vertex information, and generates connection information and attribute information corresponding to the vertex information. The three-dimensional data generator 115 may process the vertex information when generating the connection information and attribute information. For example, the three-dimensional data generator 115 may reduce the amount of data by deleting duplicate vertices, or may transform the vertex information (such as by shifting its position, rotating it, or normalizing it). The three-dimensional data generator 115 may also render the attribute information.

[0102] Furthermore, although the three-dimensional data generator 115 is a component of the three-dimensional data encoding system 110 in FIG. 12, it may be arranged externally and independently of the three-dimensional data encoding system 110.

[0103] The sensor terminal that provides the sensor data for generating the three-dimensional data may be, for example, a moving body such as an automobile, a flying object such as an airplane, a mobile terminal, a camera, etc. Furthermore, a distance sensor such as a LIDAR, a millimeter wave radar, an infrared sensor, or a range finder, a stereo camera, or a combination of multiple monocular cameras may also be used as the sensor terminal.

[0104] The sensor data may be the distance (position) of the object, monocular camera images, stereo camera images, color, reflectance, sensor attitude, orientation, gyro, sensing position (GPS information or altitude), speed, acceleration, sensing time, temperature, air pressure, humidity, or magnetism.

[0105] The three-dimensional data encoder 113 corresponds to the encoding device 100 shown in FIG. 5 and other figures. For example, the three-dimensional data encoder 113 encodes three-dimensional data to generate encoded data. The three-dimensional data encoder 113 also generates control information when encoding the three-dimensional data. The three-dimensional data encoder 113 then inputs the encoded data together with the control information to the system multiplexer 114.

[0106] The encoding method for the three-dimensional data may be an encoding method using geometry or an encoding method using a video codec. Here, the encoding method using geometry may also be referred to as a geometry-based encoding method. The encoding method using a video codec may also be referred to as a video-based encoding method.

[0107] The system multiplexer 114 multiplexes the encoded data and control information input from the 3D data encoder 113 to generate multiplexed data using a specified multiplexing method. The system multiplexer 114 may multiplex other media such as video, audio, subtitles, application data, or document files, or reference time information, along with the encoded data and control information of the 3D data. Furthermore, the system multiplexer 114 may multiplex attribute information related to the sensor data or the 3D data.

[0108] For example, the multiplexed data may have a file format for storage or a packet format for transmission. As these formats, ISOBMFF or a format based on ISOBMFF may be used. Also, MPEG-DASH, MMT, MPEG-2 TS Systems, RTP, or the like may be used.

[0109] The multiplexed data is then output as a transmission signal to the external connector 310 by the input / output processor 112. The multiplexed data may be transmitted as a transmission signal by wire or wirelessly. Alternatively, the multiplexed data is stored in an internal memory or a storage device. The multiplexed data may be transmitted to a cloud server via the Internet or may be stored in an external storage device.

[0110] For example, the transmission or storage of the multiplexed data is performed by a method according to the medium for transmission or storage, such as broadcasting or communication. The communication protocol may be http, ftp, TCP, UDP, IP, or a combination thereof. Furthermore, a pull-type communication method or a push-type communication method may be used.

[0111] For wired transmission, Ethernet (registered trademark), USB, RS-232C, HDMI (registered trademark), coaxial cable, etc. may be used. For wireless transmission, 3GPP (registered trademark), 3G / 4G / 5G defined by IEEE, wireless LAN, Wi-Fi, Bluetooth, or millimeter wave may be used. For broadcasting, for example, DVB-T2, DVB-S2, DVB-C2, ATSC3.0, or ISDB-S3 may be used.

[0112] The sensor data may be input to the three-dimensional data generator 115 or the system multiplexer 114. The three-dimensional data or encoded data may be output as a transmission signal directly to the external connector 310 via the input / output processor 112. The transmission signal output from the three-dimensional data encoding system 110 is input to the three-dimensional data decoding system 210 via the external connector 310.

[0113] Furthermore, each operation of the three-dimensional data encoding system 110 may be controlled by a controller 111 that executes an application program.

[0114] In the three-dimensional data decoding system 210, a transmission signal is input to an input / output processor 212. The input / output processor 212 decodes multiplexed data having a file format or a packet format from the transmission signal and inputs the multiplexed data to a system demultiplexer 214. The system demultiplexer 214 obtains coded data and control information from the multiplexed data and inputs them to a three-dimensional data decoder 213. The system demultiplexer 214 may extract other media or reference time information from the multiplexed data.

[0115] The three-dimensional data decoder 213 corresponds to the decoding device 200 shown in Fig. 7 etc. For example, the three-dimensional data decoder 213 decodes three-dimensional data from the encoded data based on a predefined encoding method. The three-dimensional data is then presented to the user by the presenter 215.

[0116] Additionally, additional information such as sensor data may be input to the presenter 215. The presenter 215 may present three-dimensional data based on the additional information. Additionally, a user instruction may be input from a user terminal to the user interface 216. Then, the presenter 215 may present three-dimensional data based on the input instruction.

[0117] The input / output processor 212 may acquire the three-dimensional data and the encoded data from the external connector 310 .

[0118] Furthermore, each operation of the three-dimensional data decoding system 210 may be controlled by a controller 211 that executes an application program.

[0119] 13 is a conceptual diagram showing an example of the configuration of point cloud data according to this embodiment. The point cloud data is data of a group of points representing a three-dimensional object.

[0120] Specifically, a point cloud is made up of a plurality of points, and has position information indicating the three-dimensional coordinate position of each point and attribute information indicating the attribute of each point. The position information is also expressed as geometry.

[0121] The type of attribute information may be, for example, color, reflectance, etc. One point may be associated with attribute information of one type, one point may be associated with attribute information of multiple different types, or one point may be associated with attribute information having multiple values ​​for the same type.

[0122] 14 is a conceptual diagram showing an example of a data file of point cloud data according to this embodiment. This example shows a case where there is a one-to-one correspondence between position information items and attribute information items, and shows position information and attribute information for N points that make up the point cloud data. In this example, the position information is information indicating a three-dimensional coordinate position using three axes, x, y, and z, and the attribute information is information indicating a color using RGB. A PLY file or the like can be used as a representative data file for point cloud data.

[0123] 15 is a conceptual diagram showing an example of the configuration of mesh data according to this embodiment. Mesh data is data used in CG (Computer Graphics) and the like, and is three-dimensional mesh data that shows the three-dimensional shape of an object using multiple surfaces. Each surface is also expressed as a polygon, and has a polygonal shape such as a triangle or a rectangle.

[0124] Specifically, a 3D mesh is composed of a plurality of points constituting a point cloud, as well as a plurality of edges and a plurality of faces. Each point is also expressed as a vertex or a position. Each edge corresponds to a line segment connected by two vertices. Each face corresponds to an area surrounded by three or more edges.

[0125] Furthermore, a three-dimensional mesh has position information indicating the three-dimensional coordinate positions of vertices. The position information is also expressed as vertex information or geometry. A three-dimensional mesh also has connection information indicating the relationship between multiple vertices that make up an edge or a face. The connection information is also expressed as connectivity. A three-dimensional mesh also has attribute information indicating the attributes of the vertices, edges, or faces. The attribute information in a three-dimensional mesh is also expressed as texture.

[0126] For example, the attribute information may indicate the color, reflectance, or normal vector for a vertex, edge, or face. The direction of the normal vector may represent the front and back of the face.

[0127] The mesh data may be stored in a data file format such as an object file.

[0128] 16 is a conceptual diagram showing an example of a data file of mesh data according to this embodiment. In this example, the data file includes position information G(1) to G(N) of N vertices that make up the three-dimensional mesh, and attribute information A1(1) to A1(N) of the N vertices. Also, in this example, M pieces of attribute information A2(1) to A2(M) are included. The attribute information items do not need to correspond one-to-one to vertices or faces. Furthermore, attribute information need not exist.

[0129] The connection information is represented by a combination of vertex indices. n[1, 3, 4] indicates a triangular face formed by three vertices, n=1, n=3, and n=4. Also, m[2, 4, 6] indicates that the attribute information of m=2, m=4, and m=6 corresponds to the three vertices, respectively.

[0130] Furthermore, the actual contents of the attribute information may be written in a separate file. A pointer to that content may be associated with a vertex, a face, or the like. For example, attribute information indicating an image for a face may be stored in a two-dimensional attribute map file. The file name of the attribute map and two-dimensional coordinate values ​​in the attribute map may be written in attribute information A2(1) to A2(M). The method of specifying attribute information for a face is not limited to these methods, and any method may be used.

[0131] 17 is a conceptual diagram showing types of three-dimensional data according to this embodiment. Point cloud data and mesh data may represent static objects or dynamic objects. A static object is an object that does not change over time, and a dynamic object is an object that changes over time. A static object may correspond to three-dimensional data for any point in time.

[0132] For example, point cloud data for a given point in time may be referred to as a PCC frame, mesh data for a given point in time may be referred to as a mesh frame, and PCC frames and mesh frames may be simply referred to as frames.

[0133] The area of ​​the object may be limited to a certain range, as in normal video data, or may not be limited, as in map data. The density of points or surfaces may be determined in various ways. Sparse point cloud data or sparse mesh data may be used, or dense point cloud data or dense mesh data may be used.

[0134] Next, encoding and decoding of a point cloud or a three-dimensional mesh will be described. The device, process, or syntax for encoding and decoding vertex information of a three-dimensional mesh in the present disclosure may be applied to encoding and decoding of a point cloud. The device, process, or syntax for encoding and decoding of a point cloud in the present disclosure may be applied to encoding and decoding vertex information of a three-dimensional mesh.

[0135] Furthermore, a device, process, or syntax for encoding and decoding attribute information of a point cloud in the present disclosure may be applied to encoding and decoding connectivity information or attribute information of a three-dimensional mesh.Furthermore, a device, process, or syntax for encoding and decoding connectivity information or attribute information of a three-dimensional mesh in the present disclosure may be applied to encoding and decoding attribute information of a point cloud.

[0136] Furthermore, at least some of the processing may be shared between the encoding and decoding of point cloud data and the encoding and decoding of mesh data, thereby reducing the scale of the circuit and software program.

[0137] 18 is a block diagram showing an example configuration of a three-dimensional data encoder 113 according to this embodiment. In this example, the three-dimensional data encoder 113 includes a vertex information encoder 121, an attribute information encoder 122, a metadata encoder 123, and a multiplexer 124. The vertex information encoder 121, the attribute information encoder 122, and the multiplexer 124 may correspond to the vertex information encoder 101, the attribute information encoder 103, the post-processor 105, etc. in FIG.

[0138] In this example, the three-dimensional data encoder 113 encodes the three-dimensional data according to a geometry-based encoding method, which takes into account the three-dimensional structure. In addition, in the geometry-based encoding method, attribute information is encoded using configuration information obtained in encoding the vertex information.

[0139] Specifically, first, vertex information, attribute information, and metadata included in three-dimensional data generated from sensor data are input to a vertex information encoder 121, an attribute information encoder 122, and a metadata encoder 123, respectively. Here, connectivity information included in the three-dimensional data may be treated in the same way as attribute information. In addition, in the case of point cloud data, position information may be treated as vertex information.

[0140] The vertex information encoder 121 encodes the vertex information into compressed vertex information and outputs the compressed vertex information as encoded data to the multiplexer 124. The vertex information encoder 121 also generates metadata for the compressed vertex information and outputs it to the multiplexer 124. The vertex information encoder 121 also generates configuration information and outputs it to the attribute information encoder 122.

[0141] The attribute information encoder 122 uses the configuration information generated by the vertex information encoder 121 to encode the attribute information into compressed attribute information and outputs the compressed attribute information as encoded data to the multiplexer 124. The attribute information encoder 122 also generates metadata of the compressed attribute information and outputs it to the multiplexer 124.

[0142] The metadata encoder 123 encodes compressible metadata into compressed metadata and outputs the compressed metadata as encoded data to the multiplexer 124. The metadata encoded by the metadata encoder 123 may be used to encode vertex information and attribute information.

[0143] The multiplexer 124 multiplexes the compressed vertex information, the compressed vertex information metadata, the compressed attribute information, the compressed attribute information metadata, and the compressed metadata into a bitstream, and then inputs the bitstream to the system layer.

[0144] 19 is a block diagram showing an example configuration of a three-dimensional data decoder 213 according to this embodiment. In this example, the three-dimensional data decoder 213 includes a vertex information decoder 221, an attribute information decoder 222, a metadata decoder 223, and a demultiplexer 224. The vertex information decoder 221, the attribute information decoder 222, and the demultiplexer 224 may correspond to the vertex information decoder 201, the attribute information decoder 203, the preprocessor 204, and the like in FIG.

[0145] In this example, the three-dimensional data decoder 213 decodes three-dimensional data according to a geometry-based encoding method. The three-dimensional structure is taken into consideration in the decoding according to the geometry-based encoding method. Furthermore, in the decoding according to the geometry-based encoding method, attribute information is decoded using configuration information obtained in decoding vertex information.

[0146] Specifically, first, a bitstream is input from the system layer to a demultiplexer 224. The demultiplexer 224 separates compressed vertex information, compressed vertex information metadata, compressed attribute information, compressed attribute information metadata, and compressed metadata from the bitstream. The compressed vertex information and compressed vertex information metadata are input to a vertex information decoder 221. The compressed attribute information and compressed attribute information metadata are input to an attribute information decoder 222. The metadata is input to a metadata decoder 223.

[0147] The vertex information decoder 221 decodes vertex information from the compressed vertex information using metadata of the compressed vertex information. The vertex information decoder 221 also generates configuration information and outputs it to the attribute information decoder 222. The attribute information decoder 222 decodes attribute information from the compressed attribute information using the configuration information generated by the vertex information decoder 221 and the metadata of the compressed attribute information. The metadata decoder 223 decodes metadata from the compressed metadata. The metadata decoded by the metadata decoder 223 may be used to decode the vertex information and the attribute information.

[0148] Thereafter, the vertex information, attribute information, and metadata are output as three-dimensional data from the three-dimensional data decoder 213. Note that, for example, this metadata is metadata of the vertex information and attribute information, and can be used in an application program.

[0149] 20 is a block diagram showing another example configuration of the three-dimensional data encoder 113 according to the present embodiment. In this example, the three-dimensional data encoder 113 includes a vertex image generator 131, an attribute image generator 132, a metadata generator 133, a video encoder 134, a metadata encoder 123, and a multiplexer 124. The vertex image generator 131, the attribute image generator 132, and the video encoder 134 may correspond to the vertex information encoder 101 and the attribute information encoder 103 in FIG. 6 , etc.

[0150] In this example, the 3D data encoder 113 encodes the 3D data according to a video-based encoding method. In encoding according to the video-based encoding method, multiple 2D images are generated from the 3D data, and the multiple 2D images are encoded according to a video encoding method. Here, the video encoding method may be High Efficiency Video Coding (HEVC), Versatile Video Coding (VVC), or the like.

[0151] Specifically, first, vertex information and attribute information included in three-dimensional data generated from sensor data are input to a metadata generator 133. The vertex information and attribute information are then input to a vertex image generator 131 and an attribute image generator 132, respectively. The metadata included in the three-dimensional data is then input to a metadata encoder 123. Here, connectivity information included in the three-dimensional data may be treated in the same way as attribute information. In the case of point cloud data, position information may be treated as vertex information.

[0152] The metadata generator 133 generates map information of a plurality of two-dimensional images from the vertex information and attribute information, and inputs the map information to the vertex image generator 131, the attribute image generator 132, and the metadata encoder 123.

[0153] The vertex image generator 131 generates a vertex image based on the vertex information and map information, and inputs the generated image to the video encoder 134. The attribute image generator 132 generates an attribute image based on the attribute information and map information, and inputs the generated image to the video encoder 134.

[0154] The video encoder 134 encodes the vertex images and attribute images into compressed vertex information and compressed attribute information, respectively, in accordance with a video encoding method, and outputs the compressed vertex information and compressed attribute information as encoded data to the multiplexer 124. The video encoder 134 also generates metadata for the compressed vertex information and metadata for the compressed attribute information, and outputs them to the multiplexer 124.

[0155] The metadata encoder 123 encodes the compressible metadata into compressed metadata and outputs the compressed metadata as encoded data to the multiplexer 124. The compressible metadata includes map information. The metadata encoded by the metadata encoder 123 may also be used to encode vertex information and attribute information.

[0156] The multiplexer 124 multiplexes the compressed vertex information, the compressed vertex information metadata, the compressed attribute information, the compressed attribute information metadata, and the compressed metadata into a bitstream, and then inputs the bitstream to the system layer.

[0157] 21 is a block diagram showing another example configuration of the 3D data decoder 213 according to this embodiment. In this example, the 3D data decoder 213 includes a vertex information generator 231, an attribute information generator 232, a video decoder 234, a metadata decoder 223, and a demultiplexer 224. The vertex information generator 231, the attribute information generator 232, and the video decoder 234 may correspond to the vertex information decoder 201 and the attribute information decoder 203 in FIG. 8, etc.

[0158] In this example, the 3D data decoder 213 decodes the 3D data according to a video-based coding method. In the decoding according to the video-based coding method, a plurality of 2D images are decoded according to a video coding method, and 3D data is generated from the plurality of 2D images. Here, the video coding method may be High Efficiency Video Coding (HEVC), Versatile Video Coding (VVC), or the like.

[0159] Specifically, first, a bitstream is input from the system layer to the demultiplexer 224. The demultiplexer 224 separates compressed vertex information, compressed vertex information metadata, compressed attribute information, compressed attribute information metadata, and compressed metadata from the bitstream. The compressed vertex information, compressed vertex information metadata, compressed attribute information, and compressed attribute information metadata are input to the video decoder 234. The compressed metadata is input to the metadata decoder 223.

[0160] The video decoder 234 decodes the vertex images in accordance with the video encoding method. At this time, the video decoder 234 decodes the vertex images from the compressed vertex information using the metadata of the compressed vertex information. Then, the video decoder 234 inputs the vertex images to the vertex information generator 231. The video decoder 234 also decodes the attribute images in accordance with the video encoding method. At this time, the video decoder 234 decodes the attribute images from the compressed attribute information using the metadata of the compressed attribute information. Then, the video decoder 234 inputs the attribute images to the attribute information generator 232.

[0161] The metadata decoder 223 decodes metadata from the compressed metadata. The metadata decoded by the metadata decoder 223 includes map information used to generate vertex information and attribute information. The metadata decoded by the metadata decoder 223 may also be used to decode vertex images and attribute images.

[0162] The vertex information generator 231 reproduces vertex information from the vertex image in accordance with the map information included in the metadata decoded by the metadata decoder 223. The attribute information generator 232 reproduces attribute information from the attribute image in accordance with the map information included in the metadata decoded by the metadata decoder 223.

[0163] Thereafter, the vertex information, attribute information, and metadata are output as three-dimensional data from the three-dimensional data decoder 213. Note that, for example, this metadata is metadata of the vertex information and attribute information, and can be used in an application program.

[0164] Fig. 22 is a conceptual diagram showing a specific example of encoding processing according to this embodiment. Fig. 22 shows a three-dimensional data encoder 113 and a description encoder 148. In this example, the three-dimensional data encoder 113 includes a two-dimensional data encoder 141 and a mesh data encoder 142. The two-dimensional data encoder 141 includes a texture encoder 143. The mesh data encoder 142 includes a vertex information encoder 144 and a connection information encoder 145.

[0165] The vertex information encoder 144, the connection information encoder 145, and the texture encoder 143 may correspond to the vertex information encoder 101, the connection information encoder 102, and the attribute information encoder 103 in FIG.

[0166] For example, the two-dimensional data encoder 141 operates as a texture encoder 143 and generates a texture file by encoding the texture corresponding to the attribute information as two-dimensional data according to an image encoding method or a video encoding method.

[0167] The mesh data encoder 142 also operates as a vertex information encoder 144 and a connectivity information encoder 145, and generates a mesh file by encoding the vertex information and connectivity information. The mesh data encoder 142 may further encode mapping information for textures. The encoded mapping information may then be included in the mesh file.

[0168] The description encoder 148 also generates a description file by encoding a description corresponding to metadata such as text data. The description encoder 148 may encode the description at the system layer. For example, the description encoder 148 may be included in the system multiplexer 114 of FIG. 12 .

[0169] The above operations generate a bitstream containing texture files, mesh files, and description files, which may be multiplexed into the bitstream in file formats such as glTF (Graphics Language Transmission Format) or USD (Universal Scene Description).

[0170] The three-dimensional data encoder 113 may include two mesh data encoders as the mesh data encoder 142. For example, one mesh data encoder encodes vertex information and connectivity information of a static three-dimensional mesh, and the other mesh data encoder encodes vertex information and connectivity information of a dynamic three-dimensional mesh.

[0171] Correspondingly, two mesh files may then be included in the bitstream: for example, one mesh file corresponding to a static 3D mesh and another mesh file corresponding to a dynamic 3D mesh.

[0172] Furthermore, the static three-dimensional mesh may be a three-dimensional mesh of an intraframe coded using intraprediction, and the dynamic three-dimensional mesh may be a three-dimensional mesh of an interframe coded using interprediction. Furthermore, information on the dynamic three-dimensional mesh may be differential information between vertex information or connectivity information of the three-dimensional mesh of an intraframe and vertex information or connectivity information of the three-dimensional mesh of an interframe.

[0173] Fig. 23 is a conceptual diagram showing a specific example of the decoding process according to this embodiment. Fig. 23 shows a three-dimensional data decoder 213, a description decoder 248, and a renderer 247. In this example, the three-dimensional data decoder 213 includes a two-dimensional data decoder 241, a mesh data decoder 242, and a mesh reconstructor 246. The two-dimensional data decoder 241 includes a texture decoder 243. The mesh data decoder 242 includes a vertex information decoder 244 and a connectivity information decoder 245.

[0174] The vertex information decoder 244, the connection information decoder 245, the texture decoder 243, and the mesh reconstructor 246 may correspond to the vertex information decoder 201, the connection information decoder 202, the attribute information decoder 203, and the post-processor 205 in Fig. 8. The presenter 247 may correspond to the presenter 215 in Fig. 12.

[0175] For example, the two-dimensional data decoder 241 operates as a texture decoder 243, and decodes the texture corresponding to the attribute information from the texture file as two-dimensional data in accordance with an image coding method or a video coding method.

[0176] The mesh data decoder 242 also operates as a vertex information decoder 244 and a connectivity information decoder 245 to decode vertex information and connectivity information from the mesh file. The mesh data decoder 242 may further decode mapping information for textures from the mesh file.

[0177] The description decoder 248 also decodes descriptions corresponding to metadata such as text data from the description file. The description decoder 248 may decode the descriptions at the system layer. For example, the description decoder 248 may be included in the system demultiplexer 214 of FIG. 12 .

[0178] The mesh reconstructor 246 reconstructs a 3D mesh from the vertex information, connectivity information, and textures according to the description. The renderer 247 renders and outputs the 3D mesh according to the description.

[0179] Through the above operations, a 3D mesh is reconstructed and output from a bitstream containing a texture file, a mesh file, and a description file.

[0180] The three-dimensional data decoder 213 may include two mesh data decoders as the mesh data decoder 242. For example, one mesh data decoder decodes vertex information and connectivity information of a static three-dimensional mesh, and the other mesh data decoder decodes vertex information and connectivity information of a dynamic three-dimensional mesh.

[0181] Correspondingly, two mesh files may then be included in the bitstream: for example, one mesh file corresponding to a static 3D mesh and another mesh file corresponding to a dynamic 3D mesh.

[0182] Furthermore, the static three-dimensional mesh may be a three-dimensional mesh of an intraframe coded using intraprediction, and the dynamic three-dimensional mesh may be a three-dimensional mesh of an interframe coded using interprediction. Furthermore, information on the dynamic three-dimensional mesh may be differential information between vertex information or connectivity information of the three-dimensional mesh of an intraframe and vertex information or connectivity information of the three-dimensional mesh of an interframe.

[0183] A dynamic 3D mesh coding method is sometimes called DMC (Dynamic Mesh Coding), and a video-based dynamic 3D mesh coding method is sometimes called V-DMC (Video-based Dynamic Mesh Coding).

[0184] The point cloud encoding method is sometimes called PCC (Point Cloud Compression). The point cloud video-based encoding method is sometimes called V-PCC (Video-based Point Cloud Compression). The point cloud geometry-based encoding method is sometimes called G-PCC (Geometry-based Point Cloud Compression).

[0185] <Implementation Example> Fig. 24 is a block diagram showing an implementation example of the encoding device 100 according to this embodiment. The encoding device 100 includes a circuit 151 and a memory 152. For example, multiple components of the encoding device 100 shown in Fig. 5 etc. are implemented by the circuit 151 and memory 152 shown in Fig. 24.

[0186] The circuit 151 is a circuit that performs information processing and is a circuit that can access the memory 152. For example, the circuit 151 is a dedicated or general-purpose electric circuit that encodes a three-dimensional mesh. The circuit 151 may be a processor such as a CPU. Alternatively, the circuit 151 may be a collection of multiple electric circuits.

[0187] The memory 152 is a dedicated or general-purpose memory that stores information used by the circuit 151 to encode the three-dimensional mesh. The memory 152 may be an electric circuit and may be connected to the circuit 151. The memory 152 may also be included in the circuit 151. The memory 152 may also be a collection of multiple electric circuits. The memory 152 may also be a magnetic disk, an optical disk, or the like, and may also be expressed as a storage, a recording medium, or the like. The memory 152 may also be a non-volatile memory or a volatile memory.

[0188] For example, the memory 152 may store a three-dimensional mesh or a bitstream, or may store a program for the circuit 151 to encode the three-dimensional mesh.

[0189] Note that the encoding device 100 does not necessarily have to implement all of the components shown in Figure 5 and the like, and does not necessarily have to perform all of the processes shown here. Some of the components shown in Figure 5 and the like may be included in another device, and some of the processes shown here may be executed by another device. Furthermore, the encoding device 100 may implement any combination of the components of the present disclosure, and may perform any combination of the processes of the present disclosure.

[0190] Fig. 25 is a block diagram showing an example implementation of a decoding device 200 according to this embodiment. The decoding device 200 includes a circuit 251 and a memory 252. For example, multiple components of the decoding device 200 shown in Fig. 7 and other figures are implemented by the circuit 251 and memory 252 shown in Fig. 25.

[0191] The circuit 251 is a circuit that performs information processing and is a circuit that can access the memory 252. For example, the circuit 251 is a dedicated or general-purpose electric circuit that decodes a three-dimensional mesh. The circuit 251 may be a processor such as a CPU. Alternatively, the circuit 251 may be a collection of multiple electric circuits.

[0192] The memory 252 is a dedicated or general-purpose memory that stores information for the circuit 251 to decode the 3D mesh. The memory 252 may be an electric circuit and may be connected to the circuit 251. The memory 252 may also be included in the circuit 251. The memory 252 may also be a collection of multiple electric circuits. The memory 252 may also be a magnetic disk, an optical disk, or the like, and may also be expressed as a storage, a recording medium, or the like. The memory 252 may also be a non-volatile memory or a volatile memory.

[0193] For example, the memory 252 may store a three-dimensional mesh or a bitstream, or may store a program for the circuit 251 to decode the three-dimensional mesh.

[0194] Note that the decoding device 200 does not necessarily have to implement all of the components shown in Figure 7 and the like, and does not necessarily have to perform all of the processes shown here. Some of the components shown in Figure 7 and the like may be included in another device, and some of the processes shown here may be executed by another device. Furthermore, the decoding device 200 may implement any combination of the components of the present disclosure, and may perform any combination of the processes of the present disclosure.

[0195] The encoding method and the decoding method including the steps performed by each component of the encoding device 100 and the decoding device 200 of the present disclosure may be executed by any device or system. For example, part or all of the encoding method and the decoding method may be executed by a computer including a processor, a memory, an input / output circuit, etc. In this case, the encoding method and the decoding method may be executed by the computer executing a program for causing the computer to execute the encoding method and the decoding method.

[0196] Alternatively, the program or the bitstream may be recorded on a non-transitory computer-readable recording medium such as a CD-ROM.

[0197] An example of a program may be a bitstream. For example, a bitstream including an encoded three-dimensional mesh includes syntax elements for causing the decoding device 200 to decode the three-dimensional mesh. The bitstream then causes the decoding device 200 to decode the three-dimensional mesh according to the syntax elements included in the bitstream. Thus, the bitstream may play a role similar to that of a program.

[0198] The bitstream may be an encoded bitstream containing the encoded 3D mesh, or may be a multiplexed bitstream containing the encoded 3D mesh and other information.

[0199] Furthermore, each component of the encoding device 100 and the decoding device 200 may be configured with dedicated hardware, general-purpose hardware that executes the above-mentioned programs, or a combination of these. The general-purpose hardware may be configured with a memory in which the programs are recorded and a general-purpose processor that reads and executes the programs from the memory. Here, the memory may be a semiconductor memory or a hard disk, and the general-purpose processor may be a CPU.

[0200] Furthermore, the dedicated hardware may be configured with a memory, a dedicated processor, etc. For example, the dedicated processor may execute the encoding method and the decoding method by referring to a memory for recording data.

[0201] Furthermore, as described above, each component of the encoding device 100 and the decoding device 200 may be an electric circuit. These electric circuits may form a single electric circuit as a whole, or each may be a separate electric circuit. Furthermore, these electric circuits may correspond to dedicated hardware, or may correspond to general-purpose hardware that executes the above-mentioned programs, etc. Furthermore, the encoding device 100 and the decoding device 200 may be implemented as an integrated circuit.

[0202] Furthermore, the encoding device 100 may be a transmitting device that transmits the three-dimensional mesh, and the decoding device 200 may be a receiving device that receives the three-dimensional mesh.

[0203] Displacement Encoding and Decoding The following terminology is used here by way of example:

[0204] (1) Image An image is a data unit made up of a set of pixels, and includes a picture or a block smaller than a picture. Images include both moving images and still images.

[0205] (2) Picture A picture is a unit of image processing that is made up of a set of pixels, and is also called a frame or field.

[0206] (3) Block A block is a processing unit consisting of a specific number of pixels. The term shown in the following example is also used for a block. The shape of a block is not particularly limited. A block may be, for example, a rectangular shape of M×N pixels or a square shape of M×M pixels. A block may also be a triangular shape, a circular shape, or another shape. Examples of blocks are as follows:

[0207] Slice, tile, or brick CTU, superblock, or basic division unit VPDU, processing division unit for hardware CU, processing block unit, prediction block unit (PU), or orthogonal transform block unit (TU) Sub-block

[0208] (4) Pixel or Sample A pixel or sample is the smallest point of an image, in other words, the smallest unit. Pixels or samples include not only pixels at integer positions, but also pixels at sub-pixel positions generated based on pixels at integer positions.

[0209] (5) Pixel Value or Sample Value: A pixel value or sample value is a unique value of a pixel. The pixel value or sample value may include a luma value, a chroma value, or an RGB gradation level, and may also include a depth value or a binary value of 0 or 1.

[0210] (6) Flags A flag indicates one or more bits. A flag is, for example, a parameter or index represented by two or more bits. A flag may indicate not only a value represented by a binary number, but also a value represented by a number other than a binary number.

[0211] (7) Signal: A signal is something that is symbolized or coded to transmit information. A signal includes a discrete digital signal or a continuous analog signal.

[0212] (8) Stream or Bit Stream A stream or bit stream is a digital data sequence that indicates the flow of digital data. A stream or bit stream may be a single stream, or may be configured to include multiple streams with multiple layers. A stream or bit stream may be transmitted by serial communication using a single transmission path, or may be transmitted by packet communication using multiple transmission paths.

[0213] (9) Difference: For scalar quantities, difference can include simple difference (x - y) and difference calculations, such as absolute difference (|x - y|), squared difference (x^2 - y^2), square root difference (√(x - y)), weighted difference (ax - b, where a and b are constants), or offset difference (x - y + a, where a is an offset).

[0214] (10) Sum. For scalar quantities, sums can include simple sum (x + y) and addition operations. Sum can also include absolute sum (|x + y|), sum of squares (x^2 + y^2), square root of sum (√(x + y)), weighted sum (ax + by, where a and b are constants), or offset sum (x + y + a, where a is an offset).

[0215] (11) "Based on" The expression "based on something" means that something other than that "something" may be taken into consideration. Also, "based on" can be used both when a direct result is obtained and when a result is obtained through an intermediate result.

[0216] (12) "Used" or "Using" The phrases "something was used" or "used something" mean that something other than the "something" may be taken into consideration. The phrases "used" or "used" may be used both in cases where a direct result is obtained and in cases where a result is obtained via an intermediate result.

[0217] (13) Prohibition "Prohibit" can be rephrased as "not permitted." Also, "not prohibited / prohibited" or "permitted / permitted" does not necessarily mean "obligation."

[0218] (14) "Restriction" or "Limitation" "Restriction" or "Limitation" can be rephrased as "not permitted / not allowed" or "not permitted / permitted." Furthermore, "prohibited / not prohibited" or "not permitted / permitted" does not necessarily mean "obligation." Furthermore, what is prohibited quantitatively or qualitatively may be either partial or total.

[0219] (15) Chroma The term chroma is an adjective, represented by the symbols Cb or Cr, that indicates that a sample array or a single sample represents one of the two color-difference signals associated with a primary color. The term chroma is sometimes used instead of the term chrominance.

[0220] (16) Luma The term luma is an adjective, represented by the symbols or subscripts Y or L, that indicates that a sample array or a single sample represents a monochrome signal for a primary color. The term luma is sometimes used instead of the term luminance.

[0221] The encoding / decoding system of this embodiment will be described below.

[0222] A typical three-dimensional model (also called a 3D model) digitally represents an object so that a user can explore the model using zoom, pan, and rotation in all three dimensions while it is rendered over time. One way to construct such a representation is to build a 3D mesh using triangles. The model stores the positions of the triangle vertices, their connectivity to each other, and their associated attributes (such as normals or UV patches).

[0223] Storing all this information in uncompressed form requires a very large storage space and therefore a very large bandwidth for transmission. The triangles that form the mesh often have repeating patterns and similar properties, especially in temporal and spatial neighborhoods. These repetitions can be exploited to develop efficient encoding and decoding methods for storage and transmission. One such encoding and decoding method is Video-based Dynamic Mesh Coding (V-DMC).

[0224] 26 is a block diagram showing another example of the configuration of the encoding / decoding system according to this embodiment. As shown in FIG. 26, the encoding / decoding system includes an encoding device 100 and a decoding device 200.

[0225] The encoding / decoding system accepts input three-dimensional meshes (also called 3D meshes) in the form of three-dimensional coordinates of vertices (vertex information), connectivity (connection information) and associated attributes (attribute information), which may include texture maps as well as geometry.

[0226] The encoding device 100 takes an input 3D mesh (also referred to as an input 3D mesh or input mesh) in the form of 3D coordinates of vertices, connectivity, and associated attributes. The encoding device 100 encodes all associated information into a stream. The stream may consist of a single bitstream or multiple bitstreams.

[0227] The network 300 transmits the stream generated by the encoding device to the decoding device 200. The network 300 may be the Internet, a wide area network (WAN), a local area network (LAN), or any combination thereof. Furthermore, the network 300 is not necessarily limited to a two-way communication network, but may also be a one-way communication network that transmits broadcast waves such as terrestrial digital broadcasting or satellite broadcasting. Instead of the network 300, a recording medium such as a digital versatile disc (DVD) or a blue-ray disc (BD) on which a stream is recorded may be used.

[0228] The stream is transmitted to a decoding device 200 via a network 300. The decoding device 200 decodes the bitstream and generates a 3D mesh using the 3D coordinates, connectivity, and associated attributes of the decoded vertices. The decoding device 200 outputs the generated 3D mesh (also referred to as an output 3D mesh or output mesh).

[0229] FIG. 27 is a diagram showing another example of the configuration of the encoding device 100.

[0230] As shown in FIG. 27, the encoding device 100 includes a preprocessor 1103 and a compressor 1106 .

[0231] The encoding device 100 reads an input mesh 1101 and an attribute map 1102 and passes them to a preprocessor 1103. The preprocessor 1103 processes the input mesh to extract a base mesh 1104 and displacement data 1105. The attribute map 1102, along with the extracted base mesh 1104 and displacement data 1105, are passed to a compressor 1106.

[0232] The compressor 1106 also compresses the base mesh 1104, the displacement data 1105, and the attribute map 1102 to generate a bitstream 1107. The compressor 1106 can transmit additional information to the decoding device 200 by further including metadata 1108 in the bitstream 1107.

[0233] FIG. 28 is a diagram showing another example of the configuration of the decoding device 200.

[0234] As shown in FIG. 28, the decoding device 200 includes a decompressor 2102 and a post-processor 2106 .

[0235] The decoding device 200 reads a bitstream 2101 and passes it to a decompressor 2102. The decompressor 2102 decompresses a base mesh 2103, displacement data 2104, and an attribute map 2108 from the bitstream 2101 and passes them to a post-processor 2106. An example of the displacement data 2104 is a displacement vector.

[0236] The post-processor 2106 also processes the base mesh 2103 according to the displacement data 2104 and the attribute map 2108 to generate an output mesh 2107. The post-processor 2106 may further use information from the metadata 2105 to generate the output mesh 2107.

[0237] The detailed configuration of the encoding device 100 will be described below.

[0238] FIG. 29 is a block diagram showing a detailed configuration example of the encoding device 100.

[0239] As shown in FIG. 29, the encoding device 100 includes a decimator 1201, a quantizer 1202, a base mesh encoder 1203, a base mesh decoder 1204, an inverse quantizer 1205, a subdivision unit 1206, a displacement vector calculator 1207, a wavelet transformer 1208, a quantizer 1209, an image packer 1210, a video encoder 1211, a color converter 1212, a video encoder 1213, and a multiplexer 1214.

[0240] The decimator 1201 acquires the mesh input to the encoding device 100 (corresponding to the input mesh 1101) as an original mesh, and generates a base mesh by performing a decimation process (in other words, a thinning process) on the acquired original mesh. The decimation process is a process of deleting (in other words, thinning) some of the vertices included in the original mesh. The decimation process may include a process of changing the positions of at least some of the vertices included in the original mesh, or a process of changing the connectivity of at least some of the vertices included in the original mesh. The decimation process is also simply referred to as decimation.

[0241] The base mesh generated by the decimation process has fewer vertices than the original mesh. The vertices of the base mesh may be located at different positions than the vertices of the original mesh. Also, the vertex connectivity of the base mesh may be different from the vertex connectivity of the original mesh. The decimator 1201 provides the generated base mesh to the quantizer 1202.

[0242] The quantizer 1202 quantizes the base mesh generated by the decimator 1201. The quantizer 1202 provides the quantized base mesh to the base mesh encoder 1203.

[0243] The base mesh encoder 1203 encodes the base mesh quantized by the quantizer 1202 into a bitstream (also called a base mesh bitstream) (in other words, generates a base mesh bitstream). The base mesh encoder 1203 provides the base mesh bitstream to the base mesh decoder 1204 and the multiplexer 1214.

[0244] The base mesh decoder 1204 obtains a quantized base mesh by decoding the base mesh bitstream provided by the base mesh encoder 1203. The base mesh decoder 1204 provides the quantized base mesh to the inverse quantizer 1205.

[0245] The inverse quantizer 1205 generates a base mesh (also referred to as a decoded base mesh) by inverse quantizing the quantized base mesh provided by the base mesh decoder 1204. The inverse quantizer 1205 provides the decoded base mesh to the subdivision unit 1206. There may be differences between the decoded base mesh generated by the inverse quantizer 1205 and the base mesh generated by the decimator 1201 due to the quantization and inverse quantization processes.

[0246] The subdivider 1206 performs a subdivision process on the decoded base mesh generated by the inverse quantizer 1205. The subdivision process may be a process of subdividing the faces of the decoded base mesh to make it smaller. The subdivider 1206 provides the subdivided decoded base mesh to the displacement vector calculator 1207.

[0247] Specifically, the subdivider 1206 subdivides the mesh by generating a new vertex between two connected vertices in the mesh. By repeating this process, the number of vertices in the mesh can be increased to a predetermined number. By repeating the subdivision process throughout the mesh (i.e., by performing the subdivision multiple times), multiple levels of detail (LoD) are generated.

[0248] The displacement vector calculator 1207 receives the original mesh obtained by the encoding device 100 and also receives the subdivided decoded base mesh from the subdivider 1206. The displacement vector calculator 1207 calculates a vector from a vertex of the subdivided decoded base mesh to a vertex, face, or edge of the original mesh as a displacement vector. The displacement vector calculator 1207 provides the displacement vector to the wavelet transformer 1208.

[0249] The wavelet transformer 1208 obtains wavelet coefficients by performing wavelet transform processing on the displacement vectors calculated by the displacement vector calculator 1207. The wavelet transformer 1208 provides the wavelet coefficients to the quantizer 1209. In the wavelet transform, the wavelet transformer 1208 assigns vertices to multiple LoD layers and applies, for example, a lifting transform to the displacement vectors of the vertices, thereby calculating wavelet coefficients that represent various components from low-frequency components to high-frequency components.

[0250] The quantizer 1209 quantizes the wavelet coefficients acquired by the wavelet transformer 1208. The quantizer 1209 can quantize the wavelet coefficients for each LoD layer. The quantizer 1209 provides the quantized wavelet coefficients to the image packer 1210.

[0251] The image packer 1210 generates an image containing wavelet coefficients quantized by the quantizer 1209. The image packer 1210 can generate the image by mapping the wavelet coefficients quantized by the quantizer 1209 to pixels in a two-dimensional image format. The image packer 1210 provides the generated image to the video encoder 1211. The process of mapping the quantized wavelet coefficients to pixels in the two-dimensional image format can use mapping information that represents the assignment of the quantized wavelet coefficients to pixels in the two-dimensional image format.

[0252] The video encoder 1211 encodes the image generated by the image packer 1210 into a bitstream (also called a displacement bitstream) (in other words, generates a displacement bitstream). The video encoder 1211 provides the displacement bitstream to the multiplexer 1214. The displacement bitstream may be a bitstream containing displacement information in an image format. The image format may be, for example, a format containing two chroma information pieces and one luma information piece.

[0253] The color converter 1212 obtains the attribute map obtained by the encoding device 100 as an original attribute map and performs color conversion processing on the original attribute map. The color conversion processing may include conversion processing of the color representation format or color space. The color converter 1212 provides the attribute map after color conversion processing to the video encoder 1213. Note that, although the description here takes as an example a case where the original attribute map is input to the color converter 1212, if the number or positions of vertices differ between the decoded mesh and the original mesh, the feature map may be converted to match the structure of the decoded mesh.

[0254] The video encoder 1213 encodes the attribute map converted by the color converter 1212 into a bitstream (also called an attribute bitstream) (in other words, generates an attribute bitstream). The video encoder 1213 provides the attribute bitstream to the multiplexer 1214.

[0255] The multiplexer 1214 obtains the base mesh bitstream from the base mesh encoder 1203, the displacement bitstream from the video encoder 1211, and the attribute bitstream from the video encoder 1213, and multiplexes these bitstreams to generate and output a compressed bitstream. The output of the compressed bitstream by the multiplexer 1214 may correspond to the output of the bitstream by the encoding device 100.

[0256] The process of encoding wavelet coefficients into a displacement bitstream, which is performed by the image packer 1210 and the video encoder 1211, may be performed by arithmetic coding. Alternatively, the image packer 1210 and the video encoder 1211 may be configured to select whether the process is performed by the image packer 1210 and the video encoder 1211 (also referred to as video coding) or by arithmetic coding. An example of such a configuration is described below.

[0257] Fig. 30 is a block diagram showing a modification of the detailed configuration of the encoding device 100. Fig. 30 shows a modification of the functional blocks enclosed by the dashed line in Fig. 29.

[0258] The displacement vector calculator 1207, wavelet transformer 1208, quantizer 1209, image packer 1210, and video encoder 1211 shown in FIG. 30 are the same as those shown in FIG.

[0259] As shown in FIG. 30, the encoding device 100 further includes a switch 1221, a switch 1222, and an arithmetic encoder 1223.

[0260] The switch 1221 and the switch 1222 are switchers that respectively switch whether the process of encoding wavelet coefficients into a displacement bitstream is performed by the image packer 1210 and the video coder 1211, or by the arithmetic coder 1223.

[0261] The switches 1221 and 1222 may dynamically switch the components that perform the above processing between the image packer 1210 and the video encoder 1211, and the arithmetic encoder 1223. Furthermore, the switches 1221 and 1222 may always (in other words, fixedly) use the image packer 1210 and the video encoder 1211 as the components that perform the above processing, or may always (in other words, fixedly) use the arithmetic encoder 1223.

[0262] The arithmetic coder 1223 performs the process of encoding the wavelet coefficients into a displacement bitstream by arithmetic coding.

[0263] The encoding device 100 may add information to the header information indicating whether the process of encoding the wavelet coefficients into the displacement bitstream was performed by the image packer 1210 and the video encoder 1211 (in other words, by a video encoding process) or by the arithmetic encoder 1223 (in other words, by an arithmetic encoding process). In this way, the decoding device 200 that receives the bitstream encoded as described above can appropriately decode the bitstream by referring to the header information and switching the decoding method for decoding the bitstream.

[0264] The encoding process performed by the encoding device 100 will be described in detail below.

[0265] Fig. 31 is a flow diagram showing the processing of the encoding device 100. Fig. 32 is an explanatory diagram conceptually showing the encoding of mesh frames. The processing of the encoding device 100 will be described with reference to Figs. 31 and 32.

[0266] In step S101, the encoding device 100 reads a 3D mesh frame, which is an input mesh frame, and its attributes. The input mesh frame is a mesh frame input to the encoding device 100. An example of the 3D mesh frame that is an input mesh frame is shown as mesh frame 1301 (see FIG. 32 ).

[0267] In step S102, the encoding device 100 performs a decimation process on the input mesh frame read in step S101 to generate a base mesh frame having fewer vertices than the input mesh frame. The base mesh frame generated by decimating the mesh frame 1301 is shown as a base mesh frame 1302 (see FIG. 32).

[0268] In step S103, the encoding device 100 calculates displacement information that the decoding device 200 uses to reconstruct a mesh frame. The displacement information corresponds to a displacement vector directed from a vertex of the base mesh frame generated in step S102 to a vertex of the input mesh frame. One method for calculating the displacement information is to subtract the coordinates of the vertex of the base mesh frame from the coordinates of the vertex of the input mesh frame. The displacement information calculated from the mesh frame 1301 and the base mesh frame 1302 is shown as displacement information 1303 (see FIG. 32). The displacement information 1303 is in vector format, in other words, expressed as a displacement vector.

[0269] In step S104, the encoding device 100 encodes the base mesh frame generated in step S102, the displacement information generated in step S103, and the attributes of the input mesh frame into a bitstream (corresponding to a compressed bitstream). An example of the bitstream is shown as bitstream 1304 (see FIG. 32).

[0270] Specifically, the bitstream 1304 includes vertex coordinates and connectivity information for vertices A, C, E, and F, displacement information, a video bitstream including texture data, and a compressed attribute map (see FIG. 32). The displacement information includes displacement information for displacing vertices based on vertex coordinates obtained from the subdivided base mesh frame. The compressed attribute map is texture coordinates for applying texture data to a mesh frame reconstructed using the base mesh frame and the displacement information.

[0271] The detailed configuration of the decoding device 200 will be described below.

[0272] FIG. 33 is a block diagram showing a detailed configuration example of the decoding device 200.

[0273] As shown in Figure 33, the decoding device 200 comprises a demultiplexer 2201, a base mesh decoder 2202, an inverse quantizer 2203, a subdivision unit 2204, a video decoder 2205, an image unpacker 2206, an inverse quantizer 2207, an inverse wavelet transformer 2208, a reconstructor 2209, a video decoder 2210, and a color transformer 2211.

[0274] The demultiplexer 2201 receives the compressed bitstream input to the decoding device 200 and separates it into a base mesh bitstream, a displacement bitstream, and an attribute bitstream. The demultiplexer 2201 provides the base mesh bitstream to the base mesh decoder 2202, the displacement bitstream to the video decoder 2205, and the attribute bitstream to the video decoder 2210. The compressed bitstream input to the decoding device 200 may be, for example, a compressed bitstream output by the encoding device 100, and this case will be described as an example.

[0275] The base mesh decoder 2202 obtains a quantized base mesh by decoding the base mesh bitstream provided by the demultiplexer 2201. The base mesh decoder 2202 provides the quantized base mesh to the inverse quantizer 2203.

[0276] The inverse quantizer 2203 generates a base mesh (also called a decoded base mesh) by inverse quantizing the quantized base mesh provided by the base mesh decoder 2202. The inverse quantizer 2203 provides the decoded base mesh to the subdivision unit 2204.

[0277] The subdivider 2204 performs a subdivision process on the decoded base mesh generated by the inverse quantizer 2203. The subdivision process is similar to the subdivision process performed by the subdivider 1206. The subdivider 2204 provides the subdivided decoded base mesh to the reconstructor 2209.

[0278] The video decoder 2205 decodes the displacement bitstream provided by the demultiplexer 2201 into an image, which may be an image stored by mapping quantized wavelet coefficients to pixels in a two-dimensional image format, and provides the image to the image unpacker 2206.

[0279] The image unpacker 2206 extracts quantized wavelet coefficients from the image provided by the video decoder 2205. The process of extracting the quantized wavelet coefficients from the image may use a mapping that represents the assignment of the quantized wavelet coefficients to pixels in a two-dimensional image format. The image unpacker 2206 provides the quantized wavelet coefficients extracted from the image to the inverse quantizer 2207.

[0280] The inverse quantizer 2207 generates wavelet coefficients by inverse quantizing the quantized wavelet coefficients provided by the image unpacker 2206 .

[0281] The inverse wavelet transformer 2208 generates a displacement vector (corresponding to a decoded displacement vector) by performing an inverse wavelet transform process on the wavelet coefficients provided by the inverse quantizer 2207. The inverse wavelet transform process corresponds to the inverse transform of the wavelet transform process performed by the wavelet transformer 1208. The inverse wavelet transformer 2208 provides the generated decoded displacement vector to the reconstructor 2209.

[0282] The reconstructor 2209 reconstructs a mesh (corresponding to a decoded mesh) using the subdivided decoded base mesh provided by the subdivider 2204 and the decoded displacement vector provided by the inverse wavelet transformer 2208. The reconstructor 2209 also outputs the reconstructed decoded mesh as the output mesh 2107.

[0283] The video decoder 2210 decodes the attribute bitstream provided by the demultiplexer 2201 into an attribute map (corresponding to a decoded attribute map). The video decoder 2210 provides the decoded attribute map to a color converter 2211.

[0284] The color converter 2211 performs color conversion processing on the decoded attribute map provided by the video decoder 2210. The color conversion processing corresponds to the inverse conversion of the color conversion processing performed by the color converter 1212, and may include conversion processing of color representation formats or color spaces. The color converter 2211 outputs the decoded attribute map after the color conversion processing.

[0285] The process of decoding the displacement bitstream into wavelet coefficients, performed by the video decoder 2205 and the image unpacker 2206, may be performed by arithmetic coding. Furthermore, the configuration may be such that it is selectable whether the process is performed by the video decoder 2205 and the image unpacker 2206 (also referred to as video decoding) or by arithmetic coding. An example of such a configuration is described below.

[0286] Fig. 34 is a block diagram showing a modification of the detailed configuration of the decoding device 200. Fig. 34 shows a modification of the functional blocks enclosed by the dashed line in Fig. 33.

[0287] The video decoder 2205, image unpacker 2206, inverse quantizer 2207, inverse wavelet transformer 2208, and reconstructor 2209 shown in FIG. 34 are the same as those shown in FIG.

[0288] As shown in FIG. 34, the decoding device 200 further includes a switch 2221, a switch 2222, and an arithmetic decoder 2223.

[0289] The switch 2221 and the switch 2222 are switchers that respectively switch whether the process of decoding the displacement bitstream into wavelet coefficients is performed by the video decoder 2205 and image unpacker 2206, or by the arithmetic decoder 2223.

[0290] The switch 2221 and the switch 2222 may dynamically switch the components that perform the above processing between the video decoder 2205 and the image unpacker 2206 and the arithmetic decoder 2223. Furthermore, the switch 2221 and the switch 2222 may always (in other words, fixedly) use the video decoder 2205 and the image unpacker 2206 as the components that perform the above processing, or may always (in other words, fixedly) use the arithmetic decoder 2223.

[0291] The arithmetic decoder 2223 performs arithmetic decoding to decode the displaced bitstream into wavelet coefficients.

[0292] Note that the header information may include information indicating whether the process of decoding the displaced bitstream into wavelet coefficients was performed by the video decoder 2205 and the image unpacker 2206 (in other words, by a video decoding process) or by the arithmetic decoder 2223 (in other words, by an arithmetic decoding process). In this case, the decoding device 200 can appropriately decode the bitstream by switching the decoding method for the bitstream by referring to the header information.

[0293] The decoding process performed by the decoding device 200 will be described in detail below.

[0294] Fig. 35 is a flow diagram showing the processing of the decoding device 200. Fig. 36 is an explanatory diagram conceptually showing the decoding of a 3D mesh. The processing of the decoding device 200 will be described with reference to Figs. 35 and 36.

[0295] In step S201, the decoding device 200 decodes a base mesh frame and attributes from a bitstream (corresponding to a compressed bitstream). An example of the decoded base mesh frame (corresponding to a decoded base mesh frame) is shown as a decoded base mesh frame 2301 (see FIG. 36).

[0296] In step S202, the decoding device 200 generates subdivided vertices by performing a subdivision process on the base mesh frame decoded in step S201. An example of a base mesh frame including subdivided vertices is shown as base mesh frame 2302 (see FIG. 36).

[0297] In step S203, the decoding device 200 decodes the disparity information from the bitstream (corresponding to the compressed bitstream). An example of the decoded disparity information is shown as disparity information 2303 (see FIG. 36). The disparity information 2303 is in vector format, in other words, expressed as a disparity vector.

[0298] In step S204, the decoding device 200 reconstructs the shape of the mesh frame by moving the vertices of the base mesh frame, including the subdivided vertices, to new positions using the displacement information, and then restores the mesh frame by applying attribute information. An example of the attribute is texture. An example of the reconstructed mesh frame is shown as mesh frame 2304 (see FIG. 36 ).

[0299] The subdivision is described below and is performed by a subdivider (specifically subdivider 1206 or subdivider 2204).

[0300] FIG. 37 is an explanatory diagram showing an example of subdivision.

[0301] The base mesh shown in FIG. 37(a) includes vertices A, B, and C and connectivity information indicating their connectivity.

[0302] 37(b) shows a mesh generated by the first subdivision, in other words, the mesh after the first subdivision. In the first subdivision, the subdivider generates vertices D, E, and F and connectivity information indicating their connectivity. The mesh generated by the subdivider is also referred to as LoD1 or first LoD.

[0303] Vertex D of the mesh after the first subdivision is a vertex generated by subdivision based on vertices A and B. Similarly, vertex E is a vertex generated by subdivision based on vertices B and C. Vertex F is a vertex generated by subdivision based on vertices A and C.

[0304] As an example, vertex D may be the midpoint of line segment AB (in other words, side AB) connecting vertices A and B that were the basis for its generation. Similarly, vertex E may be the midpoint of line segment AC. Vertex F may be the midpoint of line segment BC.

[0305] 37(c) shows the mesh generated by the second subdivision, i.e., the mesh after the second subdivision. In the second subdivision, the subdivider generates vertices G, H, I, J, K, L, M, N, and O and connectivity information indicating their connectivity. The mesh generated by the subdivider is also called LoD2 or second LoD.

[0306] Vertex G of the mesh after the second subdivision is a vertex generated by subdivision based on vertices A and D. Similarly, vertex H is a vertex generated by subdivision based on vertices A and E. Vertex I is a vertex generated by subdivision based on vertices B and D. Vertex J is a vertex generated by subdivision based on vertices D and F. Vertex K is a vertex generated by subdivision based on vertices E and F. Vertex L is a vertex generated by subdivision based on vertices C and E. Vertex M is a vertex generated by subdivision based on vertices B and F. Vertex N is a vertex generated by subdivision based on vertices C and F. Vertex O is a vertex generated by subdivision based on vertices D and E.

[0307] As an example, vertex G may be the midpoint of line segment AD (in other words, side AD) connecting vertices A and D, which were the source of its generation. Similarly, vertex H may be the midpoint of line segment AE. vertex I may be the midpoint of line segment BD. vertex J may be the midpoint of line segment DF. vertex K may be the midpoint of line segment EF. vertex L may be the midpoint of line segment CE. vertex M may be the midpoint of line segment BF. vertex N may be the midpoint of line segment CF. vertex O may be the midpoint of line segment DE.

[0308] The displacement of vertices will be described below with reference to Figures 38 and 39. The displacement of vertices is performed by the reconstructor 2209.

[0309] Fig. 38 is an explanatory diagram showing an example of displacement of vertices after subdivision, and Fig. 39 is an explanatory diagram showing an example of vertices of an original mesh.

[0310] The base mesh shown in FIG. 38(a) includes vertices A, B, C, and Z and connectivity information indicating their connectivity.

[0311] 38(b) shows a mesh generated by the first subdivision, in other words, a mesh after the first subdivision (i.e., the first LoD). In the first subdivision, the subdivider generates vertices S, T, U, X, or Y and connectivity information indicating their connectivity. The vertices S, T, U, X, or Y are similar to the vertices D, E, and F shown in FIG. 37(b).

[0312] 38(c) shows a mesh generated by the second subdivision, in other words, a mesh after the second subdivision (i.e., the second LoD). In the second subdivision, the subdivider generates vertices D, E, F, G, and H and connectivity information indicating their connectivity. Vertices D, E, F, G, and H are the same as vertices G, H, I, J, K, L, M, N, and O shown in FIG. 37(c).

[0313] Figure 38(d) shows a mesh including the vertices after they have been displaced after subdivision, with vertices A, B, C, D, E, F, G, H, S, T, U, X, Y, and Z shown in Figure 38(d) being located at positions displaced using displacement information from the positions of the vertices shown in Figure 38(c).

[0314] The original mesh shown in FIG. 39 is an example of the mesh input to the encoding device 100, that is, the mesh before encoding.

[0315] The mesh shown in Fig. 38 has a shape similar to that of the original mesh shown in Fig. 39. The displacement information is generated by the displacement vector calculator 1207 of the encoding device 100 as information indicating the displacement from the vertices of the base mesh to the vertices of the original mesh, and therefore, by reconstructing the mesh using the displacement information thus generated, a mesh having a shape similar to that of the original mesh is generated.

[0316] The decoding device 200 can output the mesh shown in FIG.

[0317] Next, the division of a mesh into sub-meshes will be described with reference to FIGS.

[0318] A mesh can be divided into smaller parts and coded separately, with the vertices of the mesh being divided in such a way that the coordinates and connectivity of the vertices in each part can be coded independently.

[0319] Fig. 40 is an explanatory diagram showing an example of a mesh, and Fig. 41 is an explanatory diagram showing an example of dividing a mesh into sub-meshes.

[0320] The mesh shown in FIG. 40 is the original mesh, which is sometimes called a full mesh in contrast to a sub-mesh.

[0321] Figure 41 shows how the full mesh shown in Figure 40 is divided into two sub-meshes. For vertices A, B, and C of the full mesh (see Figure 40), vertex A is duplicated to vertices A1 and A2, vertex B is duplicated to vertices B1 and B2, and vertex C is duplicated to vertices C1 and C2, thereby creating two sub-meshes (i.e., a first sub-mesh and a second sub-mesh) from the full mesh. The first sub-mesh and the second sub-mesh are each independently decodable meshes.

[0322] Packing of displacement information into image frames will be described below with reference to FIGS.

[0323] 42, 43 and 44 are explanatory diagrams showing examples of packing of displacement information into image frames. Note that image frames can also be called video frames.

[0324] The vertex displacement data is encoded as image frame data by being mapped to each component of a YUV format image frame (i.e., each of the Y component (Y Plane), U component (U Plane), and V component (V Plane)). This case will be described below as an example. As another example, the vertex displacement data may be encoded as image frame data by being mapped to each component of an RGB format image frame (each of the R component, G component, and B component).

[0325] The decoding device 200 can use an image encoding module to extract the displacement data. The displacement data can be in the form of X, Y, or Z components in a global coordinate system (e.g., a Cartesian coordinate system), or normal, tangential, or both tangential components in a local coordinate system. Methods for mapping the displacement data to an image frame include the following:

[0326] For example, in the first method, the displacement data is arranged in the image frame in scan order, and an example of packing the displacement data in this case is shown in Figure 42. The displacement data is directly mapped onto the image frame according to a predefined scan order.

[0327] Note that since an image frame has a fixed height and width, it may happen that the displacement data does not fit perfectly in the frame, in which case the remaining part of the image frame is padded with padding data (see Figure 42).

[0328] For example, in the second method, the displacement data is separated into multiple LoDs and mapped to the Y, U, and V components of the image frame. An example of packing of the displacement data in this case is shown in Figure 43. Here, the displacement data of the image frame of the next LoD starts immediately after the displacement data of the previous LoD ends. As in the first method, if the displacement data does not fit exactly into the image frame, padding is performed at the end of the image frame (see Figure 43).

[0329] For example, in the third method, displacement data corresponding to the LoD is mapped to the Y component, U component, and V component of the image frame in a manner different from that in the second method. An example of packing of the displacement data in this case is shown in Figure 44. In this way, each LoD can be decoded independently. In the third method, middle padding is performed on the displacement data of each LoD, and CTU alignment is performed together with padding at the end of the video frame (see Figure 44).

[0330] The processing performed by the encoding device 100 will be described in detail below.

[0331] 45 is a flowchart showing an example of detailed processing by the encoding device 100. The processing shown in FIG. 45 shows detailed processing included in the processing shown in FIG.

[0332] In step S301, the encoding device 100 encodes a first vertex and a first displacement vector into a bitstream. Here, the first vertex is a vertex included in a base mesh. The first displacement vector is a vector indicating the displacement from a vertex included in the base mesh (i.e., the first vertex) to a corresponding vertex included in the mesh input to the encoding device 100 (i.e., the second vertex).

[0333] In step S302, the encoding device 100 decodes (in other words, reconstructs) the first vertex and the first displacement vector from the bitstream encoded in step S301, and reconstructs the second vertex using the decoded first vertex and first displacement vector. Reconstructing the second vertex includes reconstructing the first displacement vector.

[0334] Specifically, the encoding device 100 obtains the first vertex and the first displacement vector by decoding the bitstream encoded in step S301. Then, the encoding device 100 reconstructs the second vertex by displacing the decoded first vertex using the decoded first displacement vector.

[0335] Note that the encoding device 100 can also obtain the first vertex and the first displacement vector by calculating them from the values ​​of parameters used when encoding the first vertex or the first displacement vector, rather than by decoding a bitstream in which the first vertex and the first displacement vector are encoded. Here, the parameters used when encoding the first vertex or the first displacement vector include, for example, a quantization parameter.

[0336] In step S303, the encoding apparatus 100 calculates a third vertex by interpolation using the positions of a plurality of vertices including at least the second vertex reconstructed in step S302.

[0337] In step S304, the encoding apparatus 100 calculates a vector (corresponding to a second displacement vector) indicating the displacement from the third vertex to the fourth vertex calculated in step S303.

[0338] In step S305, the encoding apparatus 100 encodes the second displacement vector calculated in step S304 into a bitstream.

[0339] By doing so, the encoding device 100 encodes the second displacement vector indicating the displacement to the fourth vertex using the third vertex indicated by the composite vector obtained by combining the reconstructed first displacement vectors as the reference point, thereby potentially reducing the amount of information in the second displacement vector. For example, compared to encoding a displacement vector indicating the displacement to the fourth vertex using a vertex calculated from the first vertices included in the base mesh as the reference point, encoding by the encoding device 100 may reduce the distance from the reference point to the fourth vertex, thereby potentially reducing the amount of information in the second displacement vector. As a result, the encoding device 100 contributes to reducing the amount of encoded information and may potentially improve the efficiency of the encoding or decoding process. In this way, the encoding device 100 may improve the encoding or decoding process for three-dimensional data.

[0340] The processing of the encoding device 100 can also be expressed as follows.

[0341] That is, the encoding device 100 encodes displacement data used to derive displacement vectors (e.g., AP, BQ, and YR in FIG. 53 ) for each of a plurality of vertices (e.g., P, Q, and R in FIG. 53 ) included in a three-dimensional mesh. Here, the displacement vector indicates the displacement of each vertex from a first position (e.g., A, B, and Y in FIG. 53 ) generated using a base mesh. The plurality of vertices includes a first vertex (e.g., R in FIG. 53 ), a second vertex (e.g., P in FIG. 53 ), and a third vertex (e.g., Q in FIG. 53 ). The displacement data of the first vertex indicates the difference between the displacement vector of the first vertex and a composite vector obtained by combining the displacement vector of the second vertex and the displacement vector of the third vertex. As a result, the encoding device 100 can sometimes reduce the amount of information in the displacement data of the first vertex because the displacement data of the first vertex indicates the difference between the displacement vector of the first vertex and a composite vector obtained by combining the displacement vector of the second vertex and the displacement vector of the third vertex. As a result, the encoding device 100 may contribute to reducing the amount of encoded information and improve the efficiency of the encoding or decoding process. In this way, the encoding device 100 can improve the encoding or decoding process for three-dimensional data.

[0342] The process performed by the decoding device 200 will be described in detail below.

[0343] 46 is a flowchart showing detailed processing by the decoding device 200. The processing shown in FIG. 46 shows detailed processing included in step S204 in FIG.

[0344] In step S401, the decoding device 200 decodes a first vertex and a first displacement vector from the bitstream. Here, the first vertex is a vertex included in the base mesh. The first displacement vector is a vector indicating the displacement from a vertex included in the base mesh (i.e., the first vertex) to a corresponding vertex included in the mesh input to the encoding device 100 (i.e., the second vertex).

[0345] In step S402, the decoding device 200 reconstructs a second vertex using the first vertex and the first displacement vector decoded in step S401. Specifically, the decoding device 200 reconstructs the second vertex by displacing the first vertex obtained by decoding in step S401 using the first displacement vector obtained by decoding in step S401.

[0346] In step S403, the decoding device 200 calculates a third vertex by interpolation using the positions of a plurality of vertices including at least the second vertex reconstructed in step S402.

[0347] In step S404, the decoding device 200 decodes the second displacement vector from the bitstream, where the second displacement vector is a vector indicating the displacement from the third vertex to the fourth vertex.

[0348] In step S405, the decoding device 200 reconstructs the fourth vertex by displacing the third vertex calculated in step S403 using the second displacement vector decoded in step S404.

[0349] In step S406, the decoding device 200 reconstructs a mesh using at least the second vertex reconstructed in step S402 and the fourth vertex reconstructed in step S405.

[0350] By doing so, the decoding device 200 decodes a second displacement vector indicating a displacement to a fourth vertex using a third vertex indicated by a composite vector obtained by combining multiple decoded first displacement vectors as a reference point, thereby reducing the amount of information in the second displacement vector. For example, compared to decoding a displacement vector indicating a displacement to a fourth vertex using a vertex calculated from multiple first vertices included in a base mesh as a reference point, decoding by the decoding device 200 may reduce the distance from the reference point to the fourth vertex, thereby reducing the amount of information in the second displacement vector. As a result, the decoding device 200 contributes to reducing the amount of encoded information and may improve the efficiency of the encoding or decoding process. In this way, the decoding device 200 can improve the encoding or decoding process for three-dimensional data.

[0351] The processing of the decoding device 200 can also be expressed as follows.

[0352] That is, the decoding device 200 decodes displacement data used to derive displacement vectors (AP, BQ, YR) for each of the multiple vertices (P, Q, R) included in the three-dimensional mesh. Here, the displacement vectors indicate the displacement of each vertex from a first position (A, B, Y) generated using the base mesh. The multiple vertices include a first vertex (R), a second vertex (P), and a third vertex (Q).

[0353] Furthermore, the decoding device 200 generates a displacement vector for the first vertex using a composite vector obtained by combining the displacement data for the first vertex, the displacement vector for the second vertex, and the displacement vector for the third vertex.

[0354] In this way, the decoding device 200 can generate a composite vector by performing an easier calculation process by combining the displacement vector of the second vertex and the displacement vector of the third vertex with equal weighting, thereby contributing to reducing the processing load or power consumption, and thus improving the encoding or decoding process for three-dimensional data.

[0355] Each of the above processes will be described in detail below.

[0356] Fig. 47 is an explanatory diagram showing the process of reconstructing the second vertex. The process of reconstructing the second vertex shown in Fig. 47 is the process executed by the encoding device 100 in step S302 (see Fig. 45) or the process executed by the decoding device 200 in step S402 (see Fig. 46).

[0357] FIG. 47 shows a mesh 6001 and a mesh 6002 generated based on the mesh 6001.

[0358] Mesh 6001 is an example of a base mesh and includes vertices A, B, C, and D. Each of vertices A, B, C, and D corresponds to a first vertex.

[0359] Mesh 6002 is an example of an original mesh and includes vertices A1, B1, C1, and D1, each of which corresponds to a second vertex.

[0360] The vertices A1, B1, C1 and D1 of the mesh 6002 are generated by displacing the vertices A, B, C and D of the mesh 6001 by a first displacement vector, respectively.

[0361] That is, vertex A1 of mesh 6002 is reconstructed by displacing vertex A of mesh 6001 by displacement vector {x1, y1, z1}.

[0362] Similarly, vertex B1 of mesh 6002 is reconstructed by displacing vertex B of mesh 6001 by displacement vector {x2, y2, z2}.

[0363] Vertex C1 of mesh 6002 is reconstructed by displacing vertex C of mesh 6001 by displacement vector {x3, y3, z3}.

[0364] Vertex D1 of mesh 6002 is reconstructed by displacing vertex D of mesh 6001 by displacement vector {x4, y4, z4}.

[0365] FIG. 48 is an explanatory diagram showing a first example of the process of calculating the third vertex.

[0366] The process of calculating the third vertex shown in FIG. 48 is the process executed in step S303 (see FIG. 45) or step S403 (see FIG. 46).

[0367] 48 shows vertices S, T, X, Y, and Z in a mesh including vertices A1, B1, C1, and D1. Each of vertices A1, B1, C1, and D1 corresponds to a second vertex, and each of vertices S, T, X, Y, and Z corresponds to a third vertex. The position of the third vertex is calculated by interpolation based on the positions of multiple vertices including at least the second vertex.

[0368] In Figure 48, vertex X is calculated by an interpolation process using at least vertex A1. Vertex Y is calculated by an interpolation process using at least vertex B1. Vertex Z is calculated by an interpolation process using at least vertex C1. Vertex S is calculated by an interpolation process using at least vertex C1. Vertex T is calculated by an interpolation process using at least vertex D1.

[0369] The interpolation process for calculating the third vertices may include, for example, a subdivision process using vertices displaced from vertices included in the base mesh, or may include a subdivision process using vertices displaced from vertices included in the mesh generated by the subdivision process.

[0370] Although an example in which the third vertex is calculated by an interpolation process using at least the second vertex has been described above, the third vertex may also be calculated by an interpolation process using at least the first vertex.

[0371] In this case, whether the third vertex is calculated by an interpolation process using the second vertex or by an interpolation process using the first vertex may be determined based on a parameter.

[0372] In the above description, the positions of the first vertex and the third vertex generated using the first vertex may also be referred to as vertex positions generated using the base mesh. In the above description, an example was given in which interpolation processing was used to derive the position of the third vertex using the position of the first vertex, but processing other than interpolation processing may also be used to derive the position of the third vertex, or the position of the third vertex may be derived using another parameter in addition to the position of the first vertex. Here, as processing other than interpolation processing, for example, interpolation processing such as Lagrange interpolation or spline interpolation may also be used.

[0373] Furthermore, although the above description has been given with reference to an example in which the position of a third vertex is calculated from the positions of two first vertices that are vertices included in a base mesh, the vertices used in the interpolation process do not have to be vertices included in the base mesh. For example, the position of another third vertex may be derived by performing an interpolation process using the position of a first vertex that is a vertex included in the base mesh and the position of a third vertex generated by an interpolation process using the first vertex. Similarly, the position of another third vertex may be derived by performing an interpolation process using the positions of two third vertices generated by an interpolation process.

[0374] The storage locations of the above parameters will be explained below.

[0375] The parameters included in the bitstream may be included in the data within the bitstream, or may be included in a header within the bitstream.

[0376] 49 and 50 are explanatory diagrams showing examples of parameter storage locations.

[0377] FIG. 49 shows an example of a bitstream in which parameters are included in the data within the bitstream.

[0378] FIG. 50 shows an example of a bitstream in which the parameters included in the bitstream are included in the header within the bitstream.

[0379] FIG. 51 is an explanatory diagram showing a second example of the process of calculating the third vertex.

[0380] 51 shows vertices S, T, X, Y, and Z in a base mesh including vertices A, B, C, and D. Each of vertices A, B, C, and D corresponds to a first vertex, and each of vertices S, T, X, Y, and Z corresponds to a third vertex. The position of the third vertex is calculated by an interpolation process based on the positions of multiple vertices including at least the first vertex.

[0381] In FIG. 51 , vertex X is calculated by an interpolation process using at least vertex A. Vertex Y is calculated by an interpolation process using at least vertex B. Vertex Z is calculated by an interpolation process using at least vertex C. Vertex S is calculated by an interpolation process using at least vertex C. Vertex T is calculated by an interpolation process using at least vertex D.

[0382] The interpolation process will be described in detail below.

[0383] 52 is an explanatory diagram showing a first example of the interpolation process. With reference to FIG. 52, a first example of a method for calculating vertex R using at least the interpolation process will be described.

[0384] FIG. 52 shows vertices A and B (corresponding to first vertices) included in the base mesh, and vertices P and Q (corresponding to second vertices) displaced from vertices A and B.

[0385] Vertex P is a vertex displaced from vertex A by a first displacement vector {x1, y1, z1}. Vertex Q is a vertex displaced from vertex B by a first displacement vector {x2, y2, z2}. Note that the relationship between a vertex included in the base mesh and a vertex displaced from the vertex by a displacement vector, such as between vertex A and vertex P, and between vertex B and vertex Q, is sometimes expressed as a "corresponding relationship."

[0386] 52 also shows vertex X (corresponding to the third vertex). Vertex X is a vertex generated by the subdivision process based on vertices P and Q. More specifically, vertex X is a point generated in the center (i.e., midpoint) of line segment PQ (in other words, side PQ) connecting vertices P and Q.

[0387] 52 also shows a vertex R (corresponding to the fourth vertex). The vertex R is displaced from the vertex X by a second displacement vector {x3, y3, z3}.

[0388] Note that the first displacement vectors {x1, y1, z1} and {x2, y2, z2}, and the second displacement vector {x3, y3, z3} are coded into the bitstream.

[0389] 53 is an explanatory diagram showing a second example of the interpolation process. With reference to FIG. 53, a second example of the method for calculating the vertex R using at least the interpolation process will be described.

[0390] In FIG. 53, vertices A, B, P, Q, X and R are shown, similar to FIG.

[0391] Also shown in FIG. 53 is a vertex Y.

[0392] Vertex Y (corresponding to the fifth vertex) is a vertex generated by the subdivision process based on vertices A and B. More specifically, vertex Y is a point generated in the center (i.e., the midpoint) of the line segment AB (in other words, the side AB) connecting vertices A and B.

[0393] Vertex R is reconstructed by displacing vertex Y by a third displacement vector {x4, y4, z4}, which is determined using the predicted vector YX {px, py, pz}.

[0394] Here, the predicted vector YX{px, py, pz} is calculated using the vector {x1, y1, z1} and the vector {x2, y2, z2}. The predicted vector YX{px, py, pz} is calculated, for example, by averaging the vector {x1, y1, z1} and the vector {x2, y2, z2}. The predicted vector YX{px, py, pz} may also be obtained by selecting one of the vectors {x1, y1, z1} and the vector {x2, y2, z2}.

[0395] The residual vector XR{rx, ry, rz} is calculated by subtracting the predicted vector YX{px, py, pz} from the vector {x4, y4, z4}.

[0396] Note that the first displacement vectors {x1, y1, z1} and {x2, y2, z2} and the residual vector {rx, ry, rz} are coded into the bitstream.

[0397] In the following, the decoding of the second displacement vector will be described.

[0398] In step S404 (see Fig. 46), the second displacement vector is decoded from the bitstream. Note that when the process described with reference to Fig. 53 is used, the residual vector is decoded from the bitstream in step S404.

[0399] For example, the first displacement vector and the second displacement vector or the residual vector are decoded from a bitstream. The first displacement vector and the second displacement vector or the residual vector may be encoded as data in an image format or as data in a format other than the image format. If the first displacement vector and the second displacement vector or the residual vector are encoded in an image format, the first displacement vector and the second displacement vector or the residual vector are obtained from image format data decoded by an image decoding device corresponding to the image codec used for encoding. If the first displacement vector and the second displacement vector or the residual vector are encoded in a format other than the image format, the first displacement vector and the second displacement vector or the residual vector are obtained by decoding the bitstream or a sub-bitstream included in the bitstream by a decoding device.

[0400] Here, the first displacement vector, the second displacement vector, or the residual vector may each have at least one component. The components of the first displacement vector, the second displacement vector, or the residual vector may be expressed using a global coordinate system, such as a Cartesian coordinate system. The first displacement vector, the second displacement vector, or the residual vector may also be expressed using a local coordinate system, such as normal, tangent, or bi-tangent, given in units of points, edges, faces, or predetermined data. Furthermore, the first displacement vector, the second displacement vector, or the residual vector may each have three components, or may be generated to have only one or two components, or may be generated to have three components and then converted to have only one or two components.

[0401] Note that the image format data generated by arranging the first displacement vector and the second displacement vector or the residual vector may have, for example, Y, U, and V components, or R, G, and B components. Furthermore, the image format data generated by arranging the first displacement vector and the second displacement vector or the residual vector may be encoded in, for example, a YUV420 chroma format, a YUV444 chroma format, or a YUV400 chroma format.

[0402] Note that the first vertex and the second vertex in the above description are, for example, vertices included in the base mesh of the mesh to be encoded. However, either one or both of the first vertex and the second vertex do not have to be vertices included in the base mesh. For example, the positions of either one or both of the first vertex and the second vertex may be positions generated by processes such as interpolation, interpolation, or extrapolation from the positions of vertices included in the base mesh of the mesh to be encoded, or may be positions generated based on the positions of vertices included in the base mesh of another mesh. Furthermore, the first displacement vector and the second displacement vector may be, for example, mapped to two tiles included in the image format data, respectively. Furthermore, the first displacement vector and the second displacement vector may be, for example, mapped to two slices included in the image format data, respectively. Furthermore, the first displacement vector and the second displacement vector may be, for example, mapped to two regions included in the image format data, respectively. Furthermore, the first displacement vector and the residual vector may be, for example, mapped to two tiles included in the image format data, respectively. Furthermore, the first displacement vector and the residual vector may be, for example, mapped to two slices included in the image format data, respectively. Furthermore, the first displacement vector and the residual vector may be mapped to two regions included in the image format data, respectively.

[0403] The reconstruction of the fourth vertex will be described below.

[0404] In step S405 (see FIG. 46), the fourth vertex is reconstructed by displacing the third vertex by the second displacement vector.

[0405] FIG. 54 is an explanatory diagram showing the process of reconstructing the fourth vertex.

[0406] FIG. 54 shows a mesh 6101 and a mesh 6102 generated based on the mesh 6101.

[0407] The mesh 6101 includes vertices A1, B1, C1, and D1, as well as vertices S, T, X, Y, and Z. Each of the vertices A1, B1, C1, and D1 corresponds to a second vertex. Each of the vertices S, T, X, Y, and Z corresponds to a third vertex.

[0408] The mesh 6102 includes vertices A1, B1, C1, and D1, as well as vertices S1, T1, X1, Y1, and Z1. The vertices A1, B1, C1, and D1 are the same as the vertices A1, B1, C1, and D1 in the mesh 6101. Each of the vertices S1, T1, X1, Y1, and Z1 corresponds to a fourth vertex.

[0409] The fourth vertex of mesh 6102 is reconstructed by displacing the third vertex of mesh 6101 by the second displacement vector.

[0410] That is, vertex X1 of mesh 6102 is reconstructed by displacing vertex X of mesh 6101 by displacement vector {x5, y5, z5}.

[0411] Similarly, vertex Y1 of mesh 6102 is reconstructed by displacing vertex Y of mesh 6101 by displacement vector {x6, y6, z6}.

[0412] Vertex Z1 of mesh 6102 is reconstructed by displacing vertex Z of mesh 6101 by displacement vector {x7, y7, z7}.

[0413] The vertex S1 of the mesh 6102 is reconstructed by displacing the vertex S of the mesh 6101 by the displacement vector {x8, y8, z8}.

[0414] Vertex T1 of mesh 6102 is reconstructed by displacing vertex T of mesh 6101 by displacement vector {x9, y9, z9}.

[0415] In the following, the reconstruction of the mesh will be described.

[0416] In step S406 (see FIG. 46), a mesh is reconstructed using at least the second and fourth vertices. The mesh reconstruction process includes, for example, applying a texture to the faces formed by the vertices.

[0417] FIG. 55 is an explanatory diagram showing an example of a reconstructed mesh.

[0418] The reconstructed mesh shown in Fig. 55 includes vertices A1, B1, C1, and D1, as well as vertices S1, T1, X1, Y1, and Z1, and has texture applied to the faces formed by the vertices.

[0419] Another example of the interpolation process will be described below.

[0420] In the first example of the interpolation process described above (see FIG. 52 ), the vertex X (corresponding to the third vertex) is the midpoint of the line segment PQ. In the example described above, the encoding device 100 generates a composite vector by combining multiple reconstructed first displacement vectors with equal weights, and then encodes the second displacement vector using the generated composite vector. By doing so, the encoding device 100 can generate the composite vector through simpler calculations by combining multiple reconstructed first displacement vectors with equal weights, which contributes to reducing processing load or power consumption. Therefore, the encoding device 100 can improve the encoding or decoding process for three-dimensional data.

[0421] In the above case, the decoding device 200 generates a composite vector by combining the reconstructed first displacement vectors with equal weights, and encodes the second displacement vector using the generated composite vector. By doing so, the decoding device 200 can generate the composite vector through easier calculation processing by combining the reconstructed first displacement vectors with equal weights, which contributes to reducing processing load or power consumption. Therefore, the decoding device 200 can improve the encoding or decoding process for three-dimensional data.

[0422] However, vertex X is not limited to the midpoint of line segment PQ. That is, the ratio PX:QX between line segment PX and line segment QX is not limited to 1:1 and may be other ratios. In other words, the encoding device 100 may generate a composite vector by combining multiple reconstructed first displacement vectors with different weights, and then encode the second displacement vector using the generated composite vector. By doing so, the encoding device 100 may be able to more appropriately generate the composite vector by combining multiple reconstructed first displacement vectors with different weights. For example, the weights of multiple first displacement vectors may be appropriately set according to the parameters of the encoding process. In this case, the composite vector may be appropriately generated according to the parameters of the encoding process, which may contribute to improving the encoding or decoding process. Therefore, the encoding device 100 may improve the encoding or decoding process for three-dimensional data.

[0423] In the above case, the decoding device 200 may generate a composite vector by combining the reconstructed first displacement vectors with different weights, and encode the second displacement vector using the generated composite vector. By doing so, the decoding device 200 may be able to more appropriately generate the composite vector by combining the reconstructed first displacement vectors with different weights. For example, the weights of the first displacement vectors may be appropriately set according to the parameters of the encoding process. In this case, the composite vector may be appropriately generated according to the parameters of the encoding process, which may contribute to improving the encoding or decoding process. Therefore, the decoding device 200 may be able to improve the encoding or decoding process for three-dimensional data.

[0424] FIG. 56 is an explanatory diagram showing a third example of the interpolation process.

[0425] The ratio PX:QX of the line segment PX to the line segment QX may be changed depending on the position of the vertex Y inserted by the subdivision of the mesh. For example, if the line segment AB is divided into three equal parts in the subdivision process, the ratio PX:QX may be set to 1:2 or 2:1 depending on the position of the vertex Y on the line segment AB. In this case, the predicted vector YX of the vector YR is determined by the following (Equation 1) and (Equation 2).

[0426] When PX:QX = 1:2,

[0427]

[0428] When PX:QX = 2:1,

[0429]

[0430] In this way, the encoding device 100 can obtain, for two second vertices, a vertex Y (i.e., a third vertex) located on the line segment connecting the two second vertices using two first displacement vectors. By doing so, the encoding device 100 can sometimes more easily reduce the amount of information in the second displacement vector by using the third vertex set on the line segment connecting the two second vertices as a reference point. Therefore, the encoding device 100 can improve the encoding or decoding process for three-dimensional data.

[0431] In the above case, the decoding device 200 can obtain, for two second vertices, a vertex Y (i.e., a third vertex) located on the line segment connecting the two second vertices using two first displacement vectors. By doing so, the decoding device 200 can sometimes more easily reduce the amount of information in the second displacement vector by using the third vertex set on the line segment connecting the two second vertices as a reference point. Therefore, the decoding device 200 can improve the encoding or decoding process for three-dimensional data.

[0432] FIG. 57 is an explanatory diagram showing a fourth example of the interpolation process.

[0433] Furthermore, the position of vertex Y generated between line segment AB can be determined using not only vertices A and B, but also a plurality of vertices connected to the vicinity of vertex Y.

[0434] For example, if the position of vertex Y is determined using multiple vertices connected to its vicinity, the coordinate of vertex Y can be the weighted average of the coordinates of the eight vertices A, B, C, D, E, F, G, and H connected to its vicinity.

[0435] In this case, PX:QX may be set to AY:BY, and the predicted vector YX of the vector YR may be determined by the following (Equation 3). Here, AY:BY=wa:wb. wa or wb is a weighting coefficient indicating the weight used in calculating the predicted vector YX, and may be any numerical value, and may be greater than or less than 0.

[0436]

[0437] In the above equation, division by 3 or (wa+wb) is performed for weighted averaging, but instead of division by 3 or (wa+wb), multiplication by a scaling parameter k may be performed as shown in the following (Equation 4).

[0438]

[0439] The scaling parameter k may be notified as an adjustment parameter from the encoding device 100 to the decoding device 200 in units of a sequence, a frame, a sub-mesh, or the like.

[0440] Here, the value of the scaling parameter k may be 1 / (wa+wb) or a value other than (wa+wb). When the value of the scaling parameter k is 1 / (wa+wb), the sum of the weights is 1, and point X is located on the line that passes through points P and Q. When the value of the scaling parameter k is a value other than 1 / (wa+wb), the sum of the weights is not 1, and point X is located at a position that is not on the line that passes through points P and Q.

[0441] In the above description, the ratio of PX to QX is calculated, but the method of calculating the predicted vector YX using the vector AP and the vector BQ is not limited to this. For example, the encoding device 100 or the decoding device 200 may calculate the weighting factor wb by which the vector AP is multiplied and the weighting factor wa by which the vector BQ is multiplied based on the ratio of AY (the distance between vertex A and vertex Y) to BY (the distance between vertex B and vertex Y).

[0442] In addition, the encoding device 100 or the decoding device 200 may use parameters other than the distance between vertices (for example, the magnitude of the displacement vectors AP and BQ or any parameters of other frames that have already been decoded) to calculate the weighting coefficients wb and wa.

[0443] In this way, the encoding method and decoding method described in the present disclosure may calculate the weighting factors wb and wa using information such as the positions or connection relationships of the encoded or decoded vertices, or the displacement vectors, which may improve the estimation accuracy of the predicted vector YX and the encoding efficiency.

[0444] The third vertex may be located at a position that is not on a line segment connecting any two second vertices selected from the plurality of second vertices. For example, when subdivision is performed using a plurality of vertices A to H that are connected in close proximity, such as vertex Y shown in Figure 57, vertex Y does not have to be located on a line segment connecting any two of the vertices A to H, in other words, it may be located at a position that is not on a line segment connecting any two of the vertices A to H.

[0445] In this way, the encoding device 100 or the decoding device 200 may be able to further reduce the amount of information in the second displacement vector by using, as a reference point, a third vertex that is set at a position that is not on a line segment connecting any two of the second vertices among the plurality of second vertices. Thus, the encoding device 100 or the decoding device 200 may be able to improve the encoding or decoding process for three-dimensional data.

[0446] <Other Examples> Although aspects of the encoding device 100 and the decoding device 200 have been described above according to the embodiments, the aspects of the encoding device 100 and the decoding device 200 are not limited to the embodiments. Modifications conceivable by those skilled in the art may be applied to the embodiments, and multiple components in the embodiments may be combined in any manner.

[0447] For example, a process performed by a specific component in the embodiment may be performed by another component instead of the specific component. Also, the order of multiple processes may be changed, or multiple processes may be performed in parallel.

[0448] Furthermore, as described above, at least some of the configurations of the present disclosure may be implemented as an integrated circuit. At least some of the processes of the present disclosure may be used as an encoding method or a decoding method. A program for causing a computer to execute the encoding method or the decoding method may be used. A non-transitory computer-readable recording medium on which the program is recorded may be used. A bitstream for causing the decoding device 200 to perform a decoding process may be used.

[0449] Furthermore, at least some of the configurations and processes of the present disclosure may be used as a transmitting device, a receiving device, a transmitting method, or a receiving method. A program for causing a computer to execute the transmitting method or the receiving method may be used. Furthermore, a non-transitory computer-readable recording medium on which the program is recorded may be used.

[0450] The present disclosure is useful, for example, in encoding devices, decoding devices, transmitting devices, receiving devices, etc. related to three-dimensional meshes, and is applicable to computer graphics systems, three-dimensional data display systems, etc.

[0451] 100 Encoding device 101, 121, 144 Vertex information encoder 102, 145 Connection information encoder 103, 122 Attribute information encoder 104, 204, 1103 Preprocessor 105, 205, 2106 Postprocessor 110 Three-dimensional data encoding system 111, 211 Controller 112, 212 Input / output processor 113 Three-dimensional data encoder 114 System multiplexer 115 Three-dimensional data generator 123 Metadata encoder 124 Multiplexer 131 Vertex image generator 132 Attribute image generator 133 Metadata generator 134 Video encoder 141 Two-dimensional data encoder 142 Mesh data encoder 143 Texture encoder 148 Description encoder 151, 251 Circuit 152, 252 Memory 200 Decoding device 201, 221, 244 Vertex information decoder 202, 245 Connection information decoder 203, 222 Attribute information decoder 210 3D data decoding system 213 3D data decoder 214 System demultiplexer 215, 247 Presentation device 216 User interface 223 Metadata decoder 224 Demultiplexer 231 Vertex information generator 232 Attribute information generator 234 Video decoder 241 2D data decoder 242 Mesh data decoder 243 Texture decoder 246 Mesh reconstructor 248 Description decoder 300 Network 310 External connector 1101 Input mesh 1102, 2108 Attribute map 1104, 2103 Base mesh 1105, 2104 Displacement data 1106 Compressor 1107, 1304, 2101 Bitstream 1108, 2105 Metadata 1201 Decimator 1202, 1209 Quantizer 1203 Base mesh encoder 1204, 2202 Base mesh decoder 1205, 2203, 2207 Inverse quantizer 1206, 2204 Subdivider 1207 Displacement vector calculator 1208 Wavelet transformer1210 Image packer 1211, 1213 Video encoder 1212, 2211 Color converter 1214 Multiplexer 1221, 1222, 2221, 2222 Switcher 1223 Arithmetic encoder 1301, 2304 Mesh frame 1302, 2301, 2302 Base mesh frame 1303, 2303 Displacement information 2102 Decompressor 2107 Output mesh 2201 Demultiplexer 2205, 2210 Video decoder 2206 Image unpacker 2208 Inverse wavelet transformer 2209 Reconstructor 2223 Arithmetic decoder 6001, 6002, 6101, 6102 Mesh

Claims

1. Memory and a circuit capable of accessing the memory; The circuit, in operation, encoding displacement data for deriving a displacement vector for each of a plurality of vertices included in the three-dimensional mesh, the displacement vector indicating a displacement of each vertex from a first position generated using the base mesh; The plurality of vertices include a first vertex, a second vertex, and a third vertex, and the displacement data of the first vertex indicates a difference between a displacement vector of the first vertex and a resultant vector obtained by combining the displacement vector of the second vertex and the displacement vector of the third vertex. Encoding device.

2. The circuit comprises: generating a composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with equal weighting, and encoding the displacement data of the first vertex using the generated composite vector; The encoding device according to claim 1 .

3. The circuit comprises: generating a composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with different weights, and encoding the displacement data of the first vertex using the generated composite vector; The encoding device according to claim 1 .

4. The composite vector is generated by weighting and combining a plurality of displacement vectors including the displacement vector of the second vertex and the displacement vector of the third vertex, and the sum of the weights is 1. The encoding device according to claim 1 .

5. The composite vector is generated by weighting and combining a plurality of displacement vectors including the displacement vector of the second vertex and the displacement vector of the third vertex, and the sum of the weights is not 1. The encoding device according to claim 1 .

6. Memory and a circuit capable of accessing the memory; The circuit, in operation, decoding displacement data used to derive a displacement vector for each of a plurality of vertices included in the three-dimensional mesh, the displacement vector indicating a displacement of each vertex from a first position generated using the base mesh, the plurality of vertices including a first vertex, a second vertex, and a third vertex; A displacement vector of the first vertex is generated using a composite vector obtained by combining the displacement data of the first vertex, the displacement vector of the second vertex, and the displacement vector of the third vertex. Decryption device.

7. The circuit comprises: generating a composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with equal weights, and decoding the displacement data of the first vertex using the generated composite vector; The decoding device according to claim 6.

8. The circuit comprises: generating a composite vector by combining the displacement vector of the second vertex and the displacement vector of the third vertex with different weights, and decoding the displacement data of the first vertex using the generated composite vector; The decoding device according to claim 6.

9. The composite vector is generated by weighting and combining a plurality of displacement vectors including the displacement vector of the second vertex and the displacement vector of the third vertex, and the sum of the weights is 1. The decoding device according to claim 6.

10. The composite vector is generated by weighting and combining a plurality of displacement vectors including the displacement vector of the second vertex and the displacement vector of the third vertex, and the sum of the weights is not 1. The decoding device according to claim 6.

11. encoding displacement data for deriving a displacement vector for each of a plurality of vertices included in the three-dimensional mesh, the displacement vector indicating a displacement of each vertex from a first position generated using the base mesh; The plurality of vertices include a first vertex, a second vertex, and a third vertex, and the displacement data of the first vertex indicates a difference between a displacement vector of the first vertex and a resultant vector obtained by combining the displacement vector of the second vertex and the displacement vector of the third vertex. Encoding method.

12. decoding displacement data used to derive a displacement vector for each of a plurality of vertices included in the three-dimensional mesh, the displacement vector indicating a displacement of each vertex from a first position generated using the base mesh, the plurality of vertices including a first vertex, a second vertex, and a third vertex; A displacement vector of the first vertex is generated using a composite vector obtained by combining the displacement data of the first vertex, the displacement vector of the second vertex, and the displacement vector of the third vertex. Decryption method.