KR20100114468A - Method and apparatus for encoding/decoding 3d contents data - Google Patents

Abstract

PURPOSE: A method and a device for encoding and decoding 3D contents data are provided to encode a normal vector value of 3D mesh data through XOR data, thereby increasing the encoding efficiency. CONSTITUTION: A 3D contents data encoding device includes a qunatizer(401), a prediction encoder(403), and an entropy encoder(405). The quantizer performs quantization about a normal vector value of a 3D mesh data. The prediction encoder performs an XOR calculation by using quantization result value. The entropy encoder performs entropy encoding by using the XOR calculation result value.

Description

Method and apparatus for encoding and decoding three-dimensional content data {METHOD AND APPARATUS FOR ENCODING / DECODING 3D CONTENTS DATA}

The present invention relates to a method and apparatus for encoding and decoding three-dimensional content data, and more particularly, to a method and apparatus for encoding and decoding normal vectors and coordinate data for a three-dimensional mesh model.

The present invention is derived from a study conducted as part of the IT source technology development project of the Ministry of Culture, Sports and Tourism. [Task management number: 2008-F-030-02, Title: Development of broadcasting convergence type full 3D restoration technology )]

Currently, a triangular mesh is widely used as a method of representing 3D content in the field of computer graphics. In 3D Mesh Coding (3DMC) for encoding data for a 3D mesh model, the 3D model is divided into connection information, location information, and other information to perform encoding. In 3DMC, 3D mesh data is encoded through quantization, prediction encoding, and entropy encoding.

However, the normal vector value of the split plane of the 3D mesh model among the 3D mesh data is encoded without predictive encoding. This is because the error occurrence rate due to prediction coding is high due to the characteristics of the normal vector. That is, the normal vector for the dividing plane is a vector representing a normal perpendicular to the dividing plane, because the spacing between the normal vectors for the two dividing planes increases even if the angle difference between the dividing planes sharing one side increases only a little.

Therefore, encoding for a normal vector performed without predictive encoding is not good in encoding efficiency, and an efficient encoding method for the normal vector is required.

An object of the present invention is to provide a method and apparatus for encoding and decoding normal vector and coordinate data for a three-dimensional mesh model.

Another object of the present invention is to provide a method and apparatus for more efficiently encoding and decoding normal vector and coordinate data for a three-dimensional mesh model.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The present invention for achieving the above object comprises the steps of performing quantization on the normal vector value of the three-dimensional mesh data; Performing an XOR operation using the quantization result value; And performing entropy encoding using the result of the XOR operation.

In addition, the present invention for achieving the above object comprises the steps of receiving a normal vector value of the encoded, three-dimensional mesh data; Receiving encoding information including prediction encoding information according to an XOR operation of a quantized normal vector value; And decoding the encoded normal vector value using the encoding information.

In addition, the present invention for achieving the above object comprises the steps of receiving mesh data for the three-dimensional mesh model; Analyzing the size of the split plane of the three-dimensional mesh model using the mesh data; And generating transformation information corresponding to the coordinates of the 3D mesh model according to the number of dividing planes having the same size.

In addition, the present invention for achieving the above object comprises the steps of receiving the transform information for the coordinates of the encoded, three-dimensional mesh model; Receiving encoding information indicating that the coordination has been converted into the conversion information according to a result of comparing the number of groups including the same dividing plane among the dividing planes of the 3D mesh model with a preset value; And decoding the transform information by using the encoding information.

According to the present invention, encoding efficiency is increased by encoding normal vector values of three-dimensional mesh data through an XOR operation.

In addition, according to the present invention, the encoding efficiency is increased by converting the coordinates into preset conversion information according to the dividing plane size of the 3D mesh model.

1 is a view for explaining a method of encoding a normal vector value in 3D Mesh Coding (3DMC) in general,
2 and 3 are diagrams for explaining a method for quantizing a normal vector,
4 is a view for explaining an apparatus and method for encoding 3D content data according to an embodiment of the present invention;
5 is a view for explaining a 3D content data decoding method according to an embodiment of the present invention;
6 is a view for explaining a texture representation for three-dimensional content;
7 is a view for explaining a method and apparatus for encoding 3D content data according to another embodiment of the present invention;
8 and 9 are views for explaining the first generation unit 707 of FIG. 7 in more detail.
10 is a diagram illustrating a bitstream including transformation information described in FIG. 9;
11 and 12 are diagrams for describing the second generation unit 709 of FIG. 7 in more detail.
FIG. 13 is a diagram illustrating a bitstream including transformation information described in FIG. 12;
14 is a diagram for describing a 3D content data decoding method according to another embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, the most preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. The above objects, features, and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, and in describing the present invention, a detailed description of well-known technology related to the present invention may unnecessarily obscure the subject matter of the present invention. If it is determined that the detailed description thereof will be omitted.

FIG. 1 is a diagram for describing a method of encoding a normal vector value in 3D Mesh Coding (3DMC) in general.

When the normal vector value is encoded in 3DMC, the input normal vector value is first quantized, and the quantized normal vector value is entropy coded without predictive coding. The entropy coded normal vector value may be generated as a bitstream and delivered to the decoder. That is, as described above, in the conventional case, normal vector values are encoded without predictive encoding.

Meanwhile, in 3DMC, Binary Arithmetic Coding (BAC) is used for entropy coding. Arithmetic Coding (AC) performs entropy coding based on probability, and BAC applies AC based on the occurrence probability of 0 and 1 bit values in the received symbol.

2 and 3 are diagrams for explaining a method for quantizing a normal vector.

The method for quantizing the normal vector may be largely performed in two steps, as shown in FIGS. 2 and 3. First, as shown in FIG. 2, the directionality with respect to the normal vector is shown, and second, as shown in FIG. 3, normals among polygons generated by further dividing the divided plane of the three-dimensional mesh model by a predetermined number of times. It represents a polygon corresponding to a vector.

First, referring to FIG. 2, in FIG. 2, the 3D object 201 may be represented by a 3D mesh model 203 having a triangular plane. Then, the directional information of the normal vector of the dividing surface 205 included in the 3D mesh model 203 is generated. In this case, the directional information of the normal vector may be represented by 3 bits, and the directional information of the normal vector with respect to another split plane of the 3D mesh model 203 is also generated.

In FIG. 3, the dividing surface 205 whose orientation is determined in FIG. 2 is divided into a plurality of triangles. It can be divided into four triangles per triangle. Using the midpoint of the plurality of triangles generated by dividing the divided surface 205 by n times, the triangle nearest to the input normal vector value is searched for. The searched triangle is represented by the representative value. If 2 bits are required to represent a triangle, 2 * n bits are required for the retrieved triangle to be represented as a representative value.

That is, the directional information and the representative values for the triangle are generated according to the quantization of the normal vector. The method of encoding and quantizing conventional normal vector values has been described above. Hereinafter, an apparatus and method for encoding 3D content data according to the present invention will be described.

4 is a diagram illustrating an apparatus and method for encoding 3D content data according to an embodiment of the present invention.

The 3D content data encoding method according to the present invention performs quantization of normal vector values of 3D mesh data. The XOR operation is performed using the quantization result value. Entropy encoding is performed using the result of the XOR operation.

Unlike the conventional method, the 3D content data encoding method according to the present invention performs prediction encoding through an XOR operation. The 3D content data encoding method according to the present invention may be performed by the encoding apparatus shown in FIG. 4.

An apparatus for encoding 3D content data according to the present invention includes a quantizer 401, a predictive encoder 403, and an entropy encoder 405.

The quantizer 401 performs quantization on normal vector values of the 3D mesh data. The quantizer 401 may quantize normal vector values through the quantization method described above.

The predictive encoder 403 performs an XOR operation using the quantization result value. The predictive encoder 403 performs an XOR operation using the correlation of the quantized result values. The performance of entropy encoding may be improved according to the XOR-based predictive encoding.

In the case of the conventional 3DMC, entropy encoding is performed by using the quantization result, and the quantization result has an even distribution. Therefore, entropy encoding through the quantization result has poor encoding efficiency. However, the 3D content data encoding apparatus according to the present invention may perform an XOR operation on the quantization result value through the predictive encoder 403 and perform entropy encoding through the predictive encoding values concentrated in one direction, thereby increasing encoding efficiency.

The prediction encoder 403 may XOR the current quantization result value Q _i and the previous quantization result value Q _i-1 as shown in Equation 1 below. Here, i denotes an index value for the split plane constituting the 3D mesh. That is, the predictive encoder 403 may XOR the quantized value of the first partition and the quantized value of the second partition. In addition, when only the first partition is quantized, the prediction encoder 403 may perform an XOR operation on the default setting and the quantization value of the first partition.

The entropy encoder 405 performs entropy encoding using the result of the XOR operation. The entropy encoder 405 may perform entropy encoding using Adaptive Arithmetic Coding (AAC).

Meanwhile, the predictive encoder 403 may perform different XOR operations according to modes. In the first mode, the predictive encoder 403 may perform XOR operation on all bits of the quantization result value, and in the second mode, the predictive encoder 403 may perform operations based on additional division of the directional information of the normal vector and the split plane among the quantization result values. Each of the position information of the set polygon may be XORed. Here, the position information of the preset polygon may be a triangular representative value corresponding to the normal vector value as described in FIG. 3.

That is, in the first mode, the predictive encoder 403 performs an XOR operation on all bits including both the value representing the direction of the normal vector and the triangle representative value at once, and in the second mode, the predictive encoder 403 determines the direction of the normal vector. XOR operation is performed by dividing the indicated value and the representative triangle value. It is preferable that the value of the number n of dividing the divided surface for quantization is predictively encoded using the second mode.

When prediction encoding is performed according to the second mode, the entropy encoder 405 entropy encodes two prediction encoding values, respectively.

Table 1 below shows the encoding efficiency according to the present invention. [Table 1] is a table representing bits required to express one normal vector when n is 3 in many 3D mesh models. As shown in Table 1, it can be seen that according to the present invention, encoding efficiency is improved by reducing about 2 bits compared to 3DMC.

FIG. 5 is a diagram illustrating a 3D content data decoding method according to an embodiment of the present invention. In FIG. 5, a method of decoding a normal vector encoded according to the present invention is described as an embodiment.

As shown in FIG. 5, the 3D content data decoding method according to the present invention starts from step S501.

In operation S501, the 3D content data decoding apparatus receives, that is, receives a normal vector value of the encoded 3D mesh data. Here, the encoded normal vector value is a normal vector value encoded by the encoding method according to the present invention, and the 3D content data decoding apparatus may receive an encoded normal vector value from the 3D content data encoding apparatus.

In operation S503, the 3D content data decoding apparatus receives encoding information including prediction encoding information according to an XOR operation of a quantized normal vector value. The encoded normal vector value and encoding information may be provided from the 3D content data encoding apparatus described in FIG. 4. The information on the method of encoding the normal vector is provided to the decoding apparatus so that the decoding apparatus can perform decoding.

The encoding information may include, for example, the current quantization result value Q _i of the normal vector value and the prediction encoding information according to the XOR operation of the previous quantization result value Q _i-1 . In addition, the encoding information may include information about the first mode and the second mode described above. Here, i denotes an index value for the split plane constituting the 3D mesh.

In operation S505, the 3D content data decoding apparatus decodes the encoded normal vector value using the encoding information. That is, the 3D content data decoding apparatus may confirm that the normal vector is predictively encoded by the XOR operation using encoding information, and may decode the transform information using the encoding information.

On the other hand, when the 3D mesh data is encoded, not only normal vectors but also coordinates of the 3D mesh model are encoded. Hereinafter, a method and apparatus for encoding a coordinate of a 3D mesh model will be described.

6 is a diagram for describing a texture representation of 3D content. In FIG. 6, a texture representation method according to Virtual Reality Modeling Language (VRML), which is currently standardized in Extensible 3D (X3D), is described as an example.

Texture coordinates are coordinates for the texture of the 3D mesh model and may be expressed as a combination of coordinate values and index values. Coordinate values for one of the two vertices and one index value constitute one division plane, that is, a patch. 6 illustrates the coordinate values and indexes according to the first to fourth patches. That is, in FIG. 6, 'point' indicates coordinate values for the first to fourth patches, and 'textCoordindex' indicates coordinate values for the first to fourth patches in the order corresponding to the index. For example, the coordinates of the first patch are represented by (0 1 2) in 'textCoordindex', where (0 1 2) is ((u ₀ v ₀ ) (u ₁ v ₁ ) (u ₂ v ₂ )) Indicates.

In the texture representation method illustrated in FIG. 6, it can be seen that a plurality of pieces of information are overlapped. That is, in the 'textCoordindex', in the case of the first patch and the fourth patch, the first coordinate and the second coordinate overlap. In addition, in the case of the first patch and the second patch, only coordinates of different orders are represented, and coordinate values overlap. As a result, in the conventional texture representation, there is a problem in that the amount of information increases by overlapping information.

Meanwhile, in FIG. 6, only the texture coordination has been described, but the coordinates of the split plane forming the three-dimensional mesh model of the three-dimensional object are also represented by a combination of coordinate values and index values, and the amount of information overlaps with the information such as texture coordination. There is an increasing problem.

FIG. 7 illustrates a method and apparatus for encoding 3D content data according to another embodiment of the present invention. In FIG. 7, a method and apparatus for encoding a coordinate of a 3D mesh model are described as an embodiment.

In the 3D content data encoding method according to the present invention, mesh data for a 3D mesh model is received. Then, using the input mesh data, the dividing plane size of the 3D mesh model is analyzed. According to the number of dividing surfaces having the same size, transform information corresponding to the coordinates of each dividing surface is generated.

In the 3D content data encoding method according to the present invention, the number of divided surfaces having the same size among the divided surfaces of the 3D mesh model is analyzed. The coordinate values of each of the divided surfaces are converted into preset conversion information according to the number of divided surfaces having the same size. For example, when the dividing planes of the 3D mesh model are all the same size as right triangles, the coordinate values of all the dividing planes need not be represented by the method described with reference to FIG. 6. Since the sizes are all the same, one coordinate value and information representing the size may be used to express coordinate values for the split plane.

Therefore, according to the present invention, since the coordinate values for the divided surfaces may not be represented, the amount of information may be reduced and the encoding efficiency may increase. A method of expressing coordinate values for the split plane using one coordinate value and information indicating a size will be described later in more detail with reference to FIGS. 7 to 13.

As shown in FIG. 7, the apparatus for encoding 3D content data according to the present invention includes an input unit 701, an analysis unit 703, and a conversion information generation unit 705. The conversion information generator 705 includes a first generator 707 and a second generator 709.

The input unit 701 receives mesh data about a 3D mesh model.

The analyzer 703 analyzes the size of the split plane of the 3D mesh model using mesh data. The analysis unit 703 analyzes the number of divided planes having the same size among the divided plane sizes of the 3D mesh model, and determines whether the number (m) of groups including the divided planes having the same size is greater than or equal to a preset value (T). Can be determined.

Here, T may be a value satisfying Equation 2 below. X and Y are the number of bits for the coordinates (u, v), and n represents the total number of divided planes of the 3D mesh model. Moreover, it is preferable that m << n is satisfied.

The transformation information generation unit 705 generates transformation information corresponding to the coordinates of the 3D mesh model according to the number of divided planes having the same size. The first generation unit 707 generates the conversion information corresponding to the coordinates when the number m of groups including the dividing planes having the same size is equal to or larger than a preset value T. The second generation unit 709 generates the conversion information corresponding to the coordinates when the number m of groups including the dividing planes having the same size is less than or equal to the preset value T.

The conversion information generated by the conversion information generator 705 may be encoded according to a preset encoding method.

According to the system design, the first generator 707 and the second generator 709 may be configured separately, and each of the first and second generators 707 and 709 may include an input unit 701 and an analyzer ( 703).

8 and 9 illustrate the first generation unit 707 of FIG. 7 in more detail. In FIG. 8 and FIG. 9, a method of expressing a texture coordinate is described as an embodiment.

The texture patches illustrated in FIG. 8 may be classified into a plurality of groups including the same size, and represent texture patches when the number of groups including the same size is equal to or larger than a preset value. When the number of groups is greater than or equal to a predetermined value, the first generator 707 generates the conversion information corresponding to the texture coordination. Hereinafter, a method in which the first generation unit 707 generates transform information for three texture coordinates will be described with reference to FIG. 9 as an embodiment.

As shown in FIG. 9, the sizes of each of the first patches T1, T2, and T3 and the second patches T4, T1, and T3, the third patches T5, T7, and T8, are the same as the right triangle and have coordinate values. There is a difference. Here, 'width' and 'height' correspond to u and v coordinates of FIG. 6. The first generator 707 generates index information for the group including the first to third patches. In this case, the first generation unit 707 may select one of the patches included in the group as a representative and give the shape list to the 'shape list'. In FIG. The patch has been selected. In addition, the index information may be generated by the analyzer 703. The analyzer 703 may generate index information while analyzing the patch size.

The first generation unit 707 generates the index information SI for the group, the cabinet information TC for each of the patches included in the group, the direction information OT, and the permutation information PI in the patch list. do. Cabinet information is information indicating the coordinates of the maximum cabinet for each patch, direction information is information indicating the direction of the patch based on the coordinates of the maximum cabinet. The permutation information is information representing a permutation of patches based on the coordinates of the maximum cabinet.

Direction information, as shown in the first box 901, indicates whether the patch is located in 1 to 4 quadrants of the X and Y planes, based on the coordinates of the maximum internal angle, as 0 to 3. The permutation information is information indicating the coordinate order of the patches, as shown in the second box 902. In the case of a triangle, there may be a total of six coordinate sequences, and the coordinate sequence is represented by 0 to 5. Depending on the permutation information, even the patches of the same coordinate may change color.

In FIG. 9, in the case of the first patch, index information is '0', and a coordinate having a maximum angle of 90 degrees is T1. The direction of the first patch is one quadrant in the X and Y planes, and the coordinate order of the first patch corresponds to zero of the second box 802. Accordingly, it can be seen that the conversion information corresponding to the texture coordination of the first patch is (0, T2, 0, 0).

In the case of the second patch, the index information is '0', and the coordinate having the maximum internal angle of 90 degrees is T4. The direction of the second patch is the three quadrant direction in the X and Y planes, and the coordinate order of the second patch corresponds to three of the second box 902. Accordingly, it can be seen that the conversion information corresponding to the texture coordination of the second patch is (0, T4, 3, 3).

That is, according to the present invention, since all coordinate values for the patch are not required in the coordinate expression method, it can be seen that the amount of information is greatly reduced, and the encoding efficiency can be increased.

The above-described encoding method is summarized as follows.

As a result of the analysis of the analysis unit 703, the first generation unit 707 generates index information according to the group when the number of groups including the division planes having the same size among the division planes of the 3D mesh model is greater than or equal to a preset value. . In the group corresponding to the index information, cabinet information indicating coordinates of the maximum cabinet is generated for each divided plane. For each divided surface, direction information based on the coordinates of the maximum internal angle is generated. For each partition, permutation information based on the coordinates of the maximum cabinet is generated.

FIG. 10 is a diagram illustrating a bitstream including transformation information described in FIG. 9.

As shown in FIG. 10, the bit stream according to the first generation unit 707 includes a first portion 1001 and a second portion 1011, and the first portion 1001 includes patches of the same size. Contains index information assigned to the group. As described above, the index information may be given to the coordinate value of the selected patch among the patches of the same size, and the first part 1001 is a part including information corresponding to 'shape list' in FIG. 9. Specifically, the first portion 1001 includes a portion 1003 representing a group, a portion 1005 representing a selected patch, and a portion 1007 representing coordinate values of the patch.

The second part 1011 is a part including information corresponding to 'patch list' in FIG. 9. That is, the second part 1011 is a part 1013 indicating patch information included in a predetermined group, a part 1015 indicating index information, cabinet information, direction information, and permutation information for a patch included in a predetermined group, and a cabinet. A portion 1017 representing a coordinate value corresponding to the information is included.

11 and 12 are diagrams for describing the second generation unit 709 of FIG. 7 in more detail. In FIG. 11 and FIG. 12, a method of expressing a texture coordinate is described as an embodiment.

The texture patch shown in FIG. 11 is a patch of irregular size, and represents a case where the number of groups including the same patch is smaller than a preset value. When the number of groups including the same patch is less than or equal to a preset value, the second generator 709 generates transform information corresponding to the texture coordination. Hereinafter, a method in which the second generation unit 709 generates transform information for texture coordination of nine patches of triangles will be described with reference to FIG. 12 as an embodiment.

In FIG. 12, the first box 1201 represents nine patches, and the second box 1203 represents a binary tree representing connection information of nine patches according to the present invention. The third box 1205 indicates a bit value according to the coordinate value and the connection information for the binary tree, and the fourth box 1207 indicates data about the bit value according to the coordinate value and the connection information shown in the third box 1205. Represents a stream.

The second generator 709 selects a preset patch among nine patches of the first box 1201. Nine patches are triangular patches, and the preset dividing plane may be one of dividing planes in which two sides or less are shared. T1 to T9 represent the coordinates of nine patches.

The second generation unit 709 generates connection information for nine patches based on the selected patch. In this case, the second generation unit 709 may generate connection information by using tree shapes shown in the second and third boxes 1203 and 1205. Here, the connection information may be the number of shared patches sharing the sides of the selected patch, the direction of the patch based on the selected patch. The second generator 709 may expand the tree by selecting the shared patch as a preset patch.

For example, the connection information may be represented by '11' when the number of patches sharing the side of the preset patch is two, and by '00' when the number of shared patches is zero. When the number of shared patches is one, the shared patches may be represented as '01' when located in the right direction and '10' when located in the left direction. Coordinate values that are not shared may be represented together. The direction of the shared patch can vary depending on the patch selected.

12 illustrates a case in which connection information for nine patches is generated based on a second patch which is a preset patch. As shown in the second and third boxes 1203 and 1205, the selected second patch is at the top, and the remaining patches are connected in the tree structure at the bottom. The first and fifth patches are connected to the second patch. That is, as shown in the first box 1201, the sides of the second patch are shared by the first and fifth patches. Therefore, the connection information for the second patch is '11' and (T4, T2, T1).

As shown in the first box 1201, the fourth and third patches are connected to the first patch, and only the eighth patch is connected to the fifth patch. Therefore, the connection information for the first patch may be represented by '11' and (T3). In addition, since the fifth patch is located on the left side of the second patch with the non-shared side at the bottom of the second patch, the connection information for the fifth patch may be represented by '10' and (T7). Like the second box 1203, the tree is expanded and connection information such as the third box 1205 may be generated.

The generated connection information may be listed as a data stream like the fourth box 1207, and it can be seen that overlapping coordinate information is included. The second generation unit 709 may reduce the amount of overlapping data by converting the overlapping coordinate information into flag bits having less information than the coordinate information. At this time, information on the order, relationship, and the like of overlapping coordinate information may be added as flag bits.

The above-described encoding method is summarized as follows.

As a result of the analysis of the analysis unit 703, the second generation unit 709 selects a preset division plane when the number of groups including the division planes having the same size among the division planes of the 3D mesh model is less than or equal to a preset value. Based on the selected dividing plane, connection information of the dividing plane of the 3D mesh model is generated. The second generation unit 709 generating the connection information more specifically determines the number of shared partitions that share the sides of the selected partition. The orientation of the shared partition surface is determined based on the selected partition surface. Connection information indicating the coordinates of the selected partition plane, the coordinates of the shared partition plane not shared with the selected partition plane, and the determination result are generated. In this case, the dividing plane of the 3D mesh model may be a triangular dividing plane, and the preset dividing plane may be one of dividing planes in which two sides or less are shared.

FIG. 13 is a diagram illustrating a bitstream including transformation information described in FIG. 12.

As shown in FIG. 10, the bit stream according to the second generator 709 includes a first portion 1301 and a second portion 1311. The first portion 1301 includes the conversion information described in FIG. 12. In this case, the first portion 1301 includes a portion 1303 including transformation information for each of a plurality of patches (Connected Components) sharing sides, for example, the transformation corresponding to the first box 1201 of FIG. 12. Information can be included in groups. The first portion 1301 may include the conversion information in the form of a data stream.

The second portion 1311 may include a portion 1313 including a patch list included in the first portion 1301, and permutation information 1315 and index information 1317 of a patch corresponding to the patch list. have.

FIG. 14 is a diagram illustrating a 3D content data decoding method according to another embodiment of the present invention. In FIG. 14, a method of decoding coordinate data encoded according to the present invention is described as an embodiment.

As shown in Fig. 14, the 3D content data decoding method according to the present invention starts from step S1401.

In operation S1401, the 3D content data decoding apparatus receives, that is, receives transform information about the coordinate of the encoded 3D mesh model.

In operation S1403, the apparatus for decoding 3D content data may include encoding information indicating that the coordinates have been converted into conversion information according to a result of comparing the number of groups including the same dividing plane among the dividing planes of the 3D mesh model with a preset value. Receive, that is, receive the input. The 3D content data decoding apparatus may receive the transform information and the encoding information for the coordinate of the 3D mesh model, encoded from the 3D content data encoding apparatus according to the present invention.

Here, the transformation information is the maximum for each divided surface in the group corresponding to the index information index information generated according to the group when the number of groups including the divided surface having the same size among the divided surfaces of the 3D mesh model is greater than or equal to a preset value. Cabinet information indicating coordinates of the cabinet, direction information based on the coordinates of the maximum cabinet for each divided plane, and permutation information based on the coordinates of the maximum cabinet for each divided plane may be included.

Alternatively, the transformation information may include connection information of the dividing plane of the 3D mesh model generated based on the preset dividing plane when the number of groups including the dividing plane having the same size among the dividing planes of the 3D mesh model is less than or equal to a preset value. It may include.

In operation S1405, the 3D content data decoding apparatus decodes the transform information by using the encoding information. That is, the 3D content data decoding apparatus may identify that the transform information corresponds to the coordinate of the 3D mesh model by using the encoding information, and may decode the transform information by using the encoding information.

Meanwhile, the encoding method for encoding and decoding the 3D content data according to the present invention as described above can be created by a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. And the recording medium includes all types of recording media (intangible medium such as a carrier wave as well as tangible media such as CD and DVD) readable by a computer.

Although the present invention has been described by means of limited embodiments and drawings, the present invention is not limited thereto and is intended to be equivalent to the technical idea and claims of the present invention by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible.

Claims (16)

Performing quantization on normal vector values of the three-dimensional mesh data;
Performing an XOR operation using the quantization result value; And
Performing entropy encoding using the result of the XOR operation
3D content data encoding method comprising a.
The method of claim 1,
The step of performing the XOR operation
XOR operation of the current quantization result value (Q _i ) and the previous quantization result value (Q _i-1 )
3D content data encoding method.
(Where i is an index value for a split plane constituting the 3D mesh)
The method of claim 2,
The step of performing the XOR operation
Performing XOR operation on directional information of the normal vector among the quantization result values; And
Performing XOR operation on position information of a preset polygon according to additional division of the division plane among the quantization result values
3D content data encoding method comprising a.
Receiving a normal vector value of the encoded three-dimensional mesh data;
Receiving encoding information including prediction encoding information according to an XOR operation of a quantized normal vector value; And
Decoding the encoded normal vector value using the encoding information
3D content data decoding method comprising a.
The method of claim 4, wherein
The XOR operation
XOR operation of the current quantization result value Q _i and the previous quantization result value Q _i-1 with respect to the normal vector value
3D content data decoding method.
(Where i is an index value for a split plane constituting the 3D mesh)
Receiving mesh data for a 3D mesh model;
Analyzing the size of the split plane of the three-dimensional mesh model using the mesh data; And
Generating transform information corresponding to coordinates of the 3D mesh model according to the number of dividing surfaces having the same size.
3D content data encoding method comprising a.
The method of claim 6,
Generating the conversion information
Generating index information according to the group when the number of groups including the dividing planes having the same size among the dividing planes of the three-dimensional mesh model is equal to or larger than a preset value;
Generating cabinet information indicative of the coordinates of the maximum cabinet for each divided surface in the group corresponding to the index information;
Generating direction information based on the coordinates of the maximum cabinet for each of the divided surfaces; And
Generating permutation information on the basis of the coordinates of the maximum cabinet for each partition;
3D content data encoding method comprising a.
The method of claim 7, wherein
The split plane of the 3D mesh model is a split plane of right triangle shape.
3D content data encoding method.
The method of claim 6,
Generating the conversion information
Selecting a preset divided surface when the number of groups including the divided surface having the same size among the divided surfaces of the 3D mesh model is less than or equal to a preset value; And
Generating connection information of a split plane of the 3D mesh model based on the selected split plane
3D content data encoding method comprising a.
The method of claim 9,
The dividing plane of the three-dimensional mesh model is a dividing plane of a triangular shape,
The preset divided plane is one of divided planes in which two sides or less are shared.
3D content data encoding method.
The method of claim 10,
Generating the connection information
Determining a number of first shared dividing planes that share sides of the selected dividing plane;
Determining a direction of the first shared partition surface based on the selected partition surface; And
Generating the connection information indicating the coordinates of the selected divided plane, the coordinates of the first shared plane not shared with the selected divided plane, and the determination result.
3D content data encoding method comprising a.
The method of claim 10,
Converting overlapping coordinate information of the connection information into flag information of a predetermined bit;
3D content data encoding method further comprising.
The method of claim 8 or 12,
Encoding the transformation information
3D content data encoding method further comprising.
Receiving transformation information about the coordinates of the encoded 3D mesh model
Receiving encoding information indicating that the coordination has been converted into the conversion information according to a result of comparing the number of groups including the same dividing plane among the dividing planes of the 3D mesh model with a preset value; And
Decoding the transform information using the encoding information.
3D content data decoding method comprising a.
The method of claim 14,
The conversion information is
Index information generated according to the group when the number of groups including the divided planes having the same size among the divided planes of the 3D mesh model is greater than or equal to a preset value;
Cabinet information indicating coordinates of the maximum cabinet for each divided plane in the group corresponding to the index information;
Direction information based on the coordinates of the maximum cabinet for each of the divided surfaces; And
Permutation information based on the coordinates of the maximum cabinet for each of the divided surfaces
3D content data decoding method comprising a.
The method of claim 14,
The conversion information is
Connection information of the split plane of the 3D mesh model generated based on the preset split plane when the number of groups including the split plane having the same size among the split planes of the 3D mesh model is less than or equal to a preset value.
3D content data decoding method comprising a.

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