Decoding method, encoding method, decoding device, and encoding device

Abstract

This decoding method determines a numerical range on the basis of whether intra-prediction or inter-prediction is used to decode encoded first information of a target three-dimensional point (S211), and switches the context to be used for entropy decoding of the encoded first information between a first context and a second context on the basis of whether or not the value of decoded second information of the target three-dimensional point is within the determined numerical range (S212). For example, in the determination (S211), a threshold value for specifying the upper limit and lower limit of the numerical range may be determined, and in the switching (S212), the determined threshold value and the absolute value of the decoded second information may be compared, and then the context to be used for the entropy decoding of the encoded first information may be switched.

Description

Technical Field

[0001] The present disclosure relates to a decoding method, an encoding method, a decoding device, and an encoding device.

Background Art

[0002] In a wide range of fields including computer vision for autonomous operation of automobiles or robots, map information, monitoring, infrastructure inspection, and video distribution, it is expected that devices or services utilizing three-dimensional data will become widespread in the future. Three-dimensional data is acquired by various methods such as distance sensors such as range finders, stereo cameras, or a combination of a plurality of monocular cameras.

[0003] As one method of representing three-dimensional data, there is a representation method called point cloud that represents the shape of a three-dimensional structure by a point group in a three-dimensional space. In a point cloud, the positions and colors of the point group are stored. While point clouds are expected to become mainstream as a representation method for three-dimensional data, the data amount of a point cloud is extremely large. Therefore, in the storage or transmission of three-dimensional data, compression of the data amount by encoding is essential, similar to two-dimensional moving images (for example, MPEG-4 AVC or HEVC standardized by MPEG).

[0004] Additionally, point cloud compression is partially supported by public libraries (Point Cloud Library) that perform point cloud-related processing.

[0005] Additionally, a technology for searching for and displaying facilities located around a vehicle using three-dimensional map data is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] In the encoding and decoding of three-dimensional data, there is a desire to improve encoding efficiency and reduce the amount of data handled by decoding devices.

[0008] The purpose of this disclosure is to provide a decoding method, encoding method, decoding device, or encoding device that can improve encoding efficiency or reduce the amount of data handled by the decoding device. [Means for solving the problem]

[0009] A three-dimensional data decoding method according to one aspect of the present disclosure determines a numerical range based on whether intra-prediction or inter-prediction is used for decoding the encoded first information of a target three-dimensional point, and switches between a first context and a second context for decoding the entropy of the encoded first information based on whether the value of the decoded second information of the target three-dimensional point falls within the determined numerical range.

[0010] A three-dimensional data encoding method according to one aspect of the present disclosure determines a numerical range based on whether intra-prediction or inter-prediction is used to encode first information of a target three-dimensional point, and switches between a first context and a second context for entropy encoding of the first information based on whether the value of second information of the target three-dimensional point falls within the determined numerical range. [Effects of the Invention]

[0011] This disclosure provides a decoding method, encoding method, decoding device, or encoding device that can improve encoding efficiency or reduce the amount of data handled by the decoding device. [Brief explanation of the drawing]

[0012] [Figure 1]Figure 1 is a block diagram of a three-dimensional data encoding device according to an embodiment. [Figure 2] Figure 2 is a block diagram of a three-dimensional data decoding device according to an embodiment. [Figure 3] Figure 3 shows an example of the syntax for node information of three-dimensional points according to the embodiment. [Figure 4] Figure 4 is a flowchart showing an example of the procedure for determining the context according to the embodiment. [Figure 5] Figure 5 is a flowchart of the three-dimensional data encoding method according to the embodiment. [Figure 6] Figure 6 is a flowchart of the three-dimensional data decoding method according to the embodiment. [Modes for carrying out the invention]

[0013] According to conventional techniques for decoding three-dimensional points, if the absolute value of the decoded information for a three-dimensional point is greater than a threshold, there is a high probability that the residual of the information to be decoded for that three-dimensional point is large, and a context suitable for large residuals is selected. Large residuals are likely to occur when the prediction is wrong. On the other hand, if the absolute value is less than or equal to the threshold, there is a high probability that the residual is small, and a context suitable for small residuals is selected. Small residuals are likely to occur when the prediction is correct.

[0014] Conventional context selection improves the encoding efficiency of the encoding device, reducing the amount of data encoded. This reduces the amount of data the decoding device has to handle, thereby lowering the processing load on the decoding device.

[0015] Conventional context selection techniques for encoding and decoding such three-dimensional points have been limited to improving encoding efficiency and reducing the amount of data handled by the decoding device, by considering only intra-prediction methods.

[0016] Accordingly, the present disclosure describes a method and apparatus for selecting a context capable of improving coding efficiency and reducing the amount of data handled in decoding, not limited to intra prediction schemes, in encoding and decoding of three-dimensional points.

[0017] A decoding method according to one aspect of the present disclosure determines a numerical range based on which of intra prediction and inter prediction is used for decoding encoded first information of a target three-dimensional point, and switches a context used for entropy decoding of the encoded first information between a first context and a second context based on whether a value of decoded second information of the target three-dimensional point falls within the determined numerical range.

[0018] The relative magnitude of the value of the second information with respect to the prediction residual of the first information may differ between the intra prediction scheme and the inter prediction scheme. Accordingly, in this aspect, depending on whether the prediction scheme is the inter prediction scheme or the intra prediction scheme, the numerical range that may include the value of the decoded second information used for determining context switching is changed based on the prediction scheme. That is, in this aspect, the numerical range is changed according to the prediction accuracy of the prediction scheme. Accordingly, a context is selected in accordance with the prediction accuracy (or the tendency for prediction to be incorrect) of each prediction scheme, so the data amount of a bitstream (encoded data) can be reduced. Therefore, the amount of data handled by the decoding apparatus can be reduced.

[0019] For example, in the determining, a threshold for specifying an upper limit value and a lower limit value of the numerical range may be determined, and in the switching, the context used for entropy decoding of the encoded first information may be switched by comparing the determined threshold with an absolute value of the decoded second information.

[0020] According to this, whether the second information falls within the numerical range can be determined by comparing the threshold with the absolute value of the second information.

[0021] For example, in the determination, a first threshold may be determined when said intra prediction is used for decoding said encoded first information, and a second threshold larger than said first threshold may be determined when said inter prediction is used for decoding said encoded first information.

[0022] In the inter prediction mode, the relative magnitude of the value of second information (e.g., prediction residual) with respect to the prediction residual of first information may be larger than that in the intra prediction mode. Therefore, this aspect increases the possibility that a context suitable for the magnitude of the prediction residual of the first information is selected by increasing the threshold when the inter prediction mode is used. However, even in the intra prediction mode, the relative magnitude of the value of the second information with respect to the prediction residual of the first information may be large.

[0023] For example, the first threshold may be 0, and the second threshold may be an integer value of 1 or greater.

[0024] For example, the decoded second information indicates a prediction residual of one of a horizontal angle and an elevation angle of the target three-dimensional point, and the encoded first information may be generated by encoding a prediction residual of a distance of the target three-dimensional point.

[0025] According to this, when the prediction residual of distance depends on the absolute value of the horizontal angle or elevation angle (that is, when the prediction accuracy of distance prediction depends on the absolute value of the horizontal angle or elevation angle), it is possible to increase the possibility of selecting a context according to the magnitude of the prediction residual.

[0026] For example, the decoded second information indicates a quantized value of a prediction residual of one of a horizontal angle and an elevation angle of the target three-dimensional point, and the encoded first information may be generated by encoding at least one prediction residual among the distance, horizontal angle, and elevation angle of the target three-dimensional point.

[0027] This increases the likelihood of selecting a context that corresponds to the magnitude of the predicted residual when at least one of the predicted residuals (distance, horizontal angle, and elevation angle) depends on the absolute value of the quantized value of the horizontal or elevation angle.

[0028] For example, the decoded second information may represent the quantized value of the predicted residual of the horizontal angle of the target three-dimensional point.

[0029] This increases the likelihood of selecting a context that corresponds to the magnitude of the predicted residual when at least one of the predicted residuals (distance, horizontal angle, and elevation angle) depends on the absolute value of the quantized horizontal angle. Furthermore, the inventors of this application have experimentally found that this combination is highly effective in improving coding efficiency and reducing the amount of data handled by the decoder.

[0030] For example, if the determination is determined to use the intra prediction for the target three-dimensional point, a non-zero first threshold may be determined.

[0031] An encoding method according to one aspect of the present disclosure determines a numerical range based on whether intra-prediction or inter-prediction is used to encode first information of a target three-dimensional point, and switches between a first context and a second context for the entropy encoding of the first information based on whether the value of the second information of the target three-dimensional point falls within the determined numerical range.

[0032] The relative magnitude of the value of the second piece of information to the prediction residual of the first piece of information may differ between the intra-prediction method and the inter-prediction method. Therefore, this embodiment changes the numerical range of the absolute value of the second piece of information used to determine context switching depending on whether the prediction method is the inter-prediction method or the intra-prediction method. In other words, this embodiment changes the numerical range depending on the accuracy of the prediction method. As a result, a context is selected according to the accuracy (or inaccuracy) of the prediction for each prediction method, thereby improving coding efficiency.

[0033] For example, in the determination, thresholds for specifying the upper and lower limits of the numerical range may be determined, and in the switching, the determined thresholds may be compared with the absolute value of the second information to switch the context used for entropy coding of the first information.

[0034] According to this method, by comparing the threshold value with the absolute value of the second piece of information, it is possible to determine whether or not the second piece of information falls within a numerical range.

[0035] For example, in the determination, if the intra prediction is used to encode the first information, a first threshold may be determined, and if the inter prediction is used to encode the first information, a second threshold greater than the first threshold may be determined.

[0036] In other words, this embodiment can increase the likelihood of selecting a context corresponding to the magnitude of the prediction residual by increasing the threshold when using the interpretation method, which is less accurate than the intraprediction method. However, there may be cases where the intraprediction method is also less accurate.

[0037] For example, the first threshold may be 0, and the second threshold may be an integer value of 1 or greater.

[0038] For example, the second information may indicate the predicted residual of either the horizontal angle or the elevation angle of the target three-dimensional point, and the first information may indicate the predicted residual of the distance of the target three-dimensional point.

[0039] According to this, when the predicted residual of distance depends on the absolute value of the horizontal or elevation angle, it is possible to increase the likelihood of selecting a context that corresponds to the magnitude of the predicted residual.

[0040] For example, the second information may represent the quantized value of one of the predicted residuals of the horizontal angle and elevation angle of the target three-dimensional point, and the first information may represent at least one predicted residual of the distance, horizontal angle, and elevation angle of the target three-dimensional point.

[0041] This increases the likelihood of selecting a context that corresponds to the magnitude of the predicted residual when at least one of the predicted residuals (distance, horizontal angle, and elevation angle) depends on the absolute value of the quantized value of the horizontal or elevation angle.

[0042] For example, the second information may represent the quantized value of the predicted residual of the horizontal angle of the target three-dimensional point.

[0043] This increases the likelihood of selecting a context that corresponds to the magnitude of the predicted residual when at least one of the predicted residuals (distance, horizontal angle, and elevation angle) depends on the absolute value of the quantized horizontal angle. Furthermore, the inventors have experimentally found that this combination has a significant effect in reducing the reduction of coding efficiency.

[0044] For example, if the determination is determined to use the intra prediction for the target three-dimensional point, a non-zero first threshold may be determined.

[0045] A decoding device according to one aspect of the present disclosure comprises a processor and a memory, wherein the processor uses the memory to determine a numerical range based on whether intra-prediction or inter-prediction is used for decoding the encoded first information of a target three-dimensional point, and switches between a first context and a second context for the context used for entropy decoding of the encoded first information based on whether the value of the decoded second information of the target three-dimensional point falls within the determined numerical range.

[0046] An encoding device according to one aspect of the present disclosure comprises a processor and a memory, wherein the processor uses the memory to determine a numerical range based on whether intra-prediction or inter-prediction is used for encoding first information of a target three-dimensional point, and switches between a first context and a second context for the entropy encoding of the first information based on whether the value of the second information of the target three-dimensional point falls within the determined numerical range.

[0047] These comprehensive or specific embodiments may be implemented as a system, method, integrated circuit, computer program, or recording medium such as a computer-readable CD-ROM, or as any combination of a system, method, integrated circuit, computer program, and recording medium.

[0048] The embodiments will be described in detail below with reference to the drawings. Note that the embodiments described below are all specific examples of this disclosure. The numerical values, shapes, materials, components, arrangement and connection configurations of components, steps, and the order of steps shown in the following embodiments are examples only and are not intended to limit this disclosure. Furthermore, components in the following embodiments that are not described in an independent claim will be described as optional components.

[0049] (Embodiment) First, the configuration of the three-dimensional data encoding device and the three-dimensional data decoding device according to this embodiment will be described. Figure 1 is a block diagram showing the configuration of the three-dimensional data encoding device 100. The three-dimensional data encoding device 100 generates a bitstream (encoded stream) by encoding point cloud data, which is three-dimensional data.

[0050] A point cloud is a collection of multiple three-dimensional points that represent the three-dimensional shape of an object. Point cloud data includes positional and attribute information for the multiple three-dimensional points. This positional information indicates the three-dimensional position of each point. This positional information is sometimes also referred to as geometry information.

[0051] For example, positional information is expressed in polar coordinates and includes one distance component and two directional components (angle components). Specifically, positional information includes distance d, elevation angle θ, and horizontal angle Φ. Point cloud data is, for example, data obtained from a laser sensor such as LiDAR. Note that positional information may also be expressed in Cartesian coordinates (x, y, z).

[0052] Attribute information can include, for example, color, reflectance, or normal vector. A single three-dimensional point may have one attribute or multiple attribute pieces of information.

[0053] Note that the three-dimensional data is not limited to point cloud data; it may also be other types of three-dimensional data such as mesh data. Mesh data (also called three-dimensional mesh data) is a data format used in computer graphics (CG), and it represents the three-dimensional shape of an object as a collection of surface information. For example, mesh data includes point cloud information (e.g., vertex information). Therefore, the same methods as those used for point cloud data can be applied to this point cloud information.

[0054] Although Figure 1 shows a processing unit for encoding positional information of point cloud data, the three-dimensional data encoding device 100 may also include other processing units, such as a processing unit for encoding attribute information.

[0055] The three-dimensional data encoding device 100 includes a subtraction unit 102, a quantization unit 103, an entropy encoding unit 104, an inverse quantization unit 105, an addition unit 106, a buffer 108, an intra prediction unit 109, a buffer 110, a motion detection compensation unit 111, an inter prediction unit 112, and a switching unit 113.

[0056] The subtraction unit 102 generates a predicted residual by subtracting the predicted value from the position information contained in the input point cloud data to be encoded. The quantization unit 103 quantizes the predicted residual. The entropy encoding unit 104 generates a bitstream by entropy encoding the quantized predicted residual. The entropy encoding unit 104 also entropy encodes control information and adds the encoded information to the bitstream.

[0057] The inverse quantization unit 105 generates prediction residuals by inverse quantization of the quantized prediction residuals obtained by the quantization unit 103. The addition unit 106 restores the position information by adding the prediction value to the prediction residuals generated by the inverse quantization unit 105. The buffer 108 holds the restored position information as a reference point set for intra-prediction. The buffer 110 holds the restored position information as a reference point set for inter-prediction.

[0058] Note that the reconstructed position information may not perfectly match the original position information because it contains quantization errors. The three-dimensional points reconstructed through this encoding and decoding process are referred to as the encoded three-dimensional points, the decoded three-dimensional points, or the processed three-dimensional points.

[0059] The intra-prediction unit 109 calculates a predicted value using the position information of one or more reference points, which are other processed three-dimensional points belonging to the same frame as the three-dimensional point to be processed (hereinafter referred to as the target point). For example, the intra-prediction unit 109 performs intra-prediction using a prediction tree. A prediction tree is a tree structure that shows the reference relationships in the prediction process. For example, the position information of the parent node is referenced in the prediction process of the target node (target point). In addition, the position information of multiple nodes including the parent node (for example, a grandparent node and a great-grandparent node) may be referenced in the prediction process.

[0060] The motion detection and compensation unit 111 detects the displacement (motion detection) between the target frame, which is the frame containing the target points, and the reference frame, which is a different frame from the target frame, and corrects (motion compensation) the position information of the point cloud contained in the reference frame based on the detected displacement. The information indicating the detected displacement (motion information) is stored, for example, in a bitstream.

[0061] The interpretation unit 112 calculates predicted values ​​using the positional information of one or more reference points included in the motion-compensated point cloud. Motion detection and motion compensation are not required.

[0062] The switching unit 113 selects either the predicted value calculated by the intra-prediction unit 109 or the predicted value obtained by the inter-prediction unit 112, and outputs the selected predicted value to the subtraction unit 102 and the addition unit 106. In other words, the switching unit 113 switches between using intra-prediction or inter-prediction. For example, this switching may be determined by comparing the cost (code amount) of using intra-prediction with the cost of using inter-prediction and using the method with the lower cost, or it may be determined based on external instructions, or it may be determined based on the point cloud or information associated with the point cloud. Information indicating whether intra-prediction or inter-prediction is used is also stored in the bitstream.

[0063] Next, the configuration of the three-dimensional data decoding device 200, which decodes the bitstream generated by the three-dimensional data encoding device 100, will be described. Figure 2 is a block diagram of the three-dimensional data decoding device 200 according to this embodiment. Although Figure 2 shows the processing unit for decoding the position information of the point cloud, the three-dimensional data decoding device 200 may also include other processing units, such as a processing unit for decoding the attribute information of the point cloud. For example, the three-dimensional data decoding device 200 generates decoded point cloud data by decoding the bitstream generated by the three-dimensional data encoding device 100 shown in Figure 1.

[0064] The three-dimensional data decoding device 200 includes an entropy decoding unit 201, an inverse quantization unit 202, an addition unit 203, a buffer 205, an intra prediction unit 206, a buffer 207, a motion compensation unit 208, an inter prediction unit 209, and a switching unit 210.

[0065] The three-dimensional data decoding device 200 acquires the bitstream generated by the three-dimensional data encoding device 100.

[0066] The entropy decoding unit 201 generates quantized prediction residuals and control information by entropy decoding the bitstream.

[0067] The inverse quantization unit 202 generates predicted residuals by inverse quantization of the quantized predicted residuals obtained by the entropy decoding unit 201. The addition unit 203 restores the position information by adding the predicted value to the predicted residuals generated by the inverse quantization unit 202. This position information is output as decoded point cloud data.

[0068] Buffer 205 holds the restored position information as a set of reference points for intra-prediction. Buffer 207 holds the restored position information as a set of reference points for intra-prediction. The intra-prediction unit 206 calculates the predicted value using the position information of one or more reference points, which are other three-dimensional points belonging to the same frame as the target point. For example, the intra-prediction unit 206 performs intra-prediction using a prediction tree.

[0069] The motion compensation unit 208 acquires motion information from the bitstream that indicates the displacement between the target frame and the reference frame, and corrects (motion compensates for) the position information of the point cloud included in the reference frame based on the displacement indicated by the motion information. The interpretation unit 209 calculates a predicted value using the position information of one or more reference points included in the motion-compensated point cloud. Motion compensation is not required.

[0070] The switching unit 210 selects either the predicted value calculated by the intra-prediction unit 206 or the predicted value obtained by the inter-prediction unit 209, and outputs the selected predicted value to the addition unit 203. For example, this switching is performed based on information included in the bitstream indicating whether to use intra-prediction or inter-prediction.

[0071] Figure 3 shows an example of the syntax for node information (geometry_prediction_tree_node) of a three-dimensional point according to the embodiment. This syntax is an example of the information for each node in the prediction tree.

[0072] The InterFrameFlag indicates whether interframe prediction is enabled. The InterFrameFlag is set according to the higher-level syntax (SPS, GPS, or slice header, etc.). SPS (Sequence Parameter Set) is a sequence-level parameter set (control information) containing multiple frames. Furthermore, SPS is a parameter set common to both position information and attribute information. GPS (Geometry Parameter Set) is a frame-level parameter set, specifically for position information.

[0073] The `intra_pred_flag` indicates whether the prediction method applied to the encoding or decoding of the target point is intraprediction or interprediction (i.e., intraprediction or interprediction). For example, a value of 1 indicates intraprediction, and a value of 0 indicates interprediction.

[0074] For example, intra_pred_flag is included in the node information if InterFrameFlag indicates that inter-prediction is available, and not included in the node information if InterFrameFlag indicates that inter-prediction is unavailable (disabled).

[0075] When intra-predation is applied (intra_pred_flag=1), the node information includes pred_mode. pred_mode indicates the prediction mode applied to the encoding or decoding of the target point. The prediction mode is information that indicates how the intra-predicted point applied to the target point is determined. For example, the prediction mode indicates how the predicted point is calculated based on the position of one or more higher-level nodes of the target point in the prediction tree.

[0076] When interpred prediction is applied (intra_pred_flag=0), node information includes one or more inter_ref_frame_idx and one or more inter_ref_point_idx.

[0077] NumRefFrames indicates the number of frames (point clouds) referenced in the interpretation and is set according to the higher-level syntax (SPS, GPS, or slice header, etc.).

[0078] The `inter_ref_frame_idx` is included in the node information if interpretation is applied (intra_pred_flag=0) and `NumRefFrames` is greater than 1. `inter_ref_frame_idx` indicates the frame referenced in the interpretation of the target point.

[0079] NumRefPoints indicates the number of prediction points referenced in interpretation. inter_ref_point_idx is included in the node information if interpretation is applied (intra_pred_flag=0) and NumRefPoints is greater than 1. inter_ref_point_idx indicates the prediction point referenced in the interpretation of the target point.

[0080] The gps_alt_coordinates_flag indicates whether the point cloud encoding or decoding is performed using Cartesian coordinates (value 0) or non-Cartesian coordinates (e.g., polar coordinates) (value 1). This gps_alt_coordinates_flag is added to the bitstream.

[0081] If gps_alt_coordinates_flag indicates that polar coordinates are being used (for example, gps_alt_coordinates_flag=1), the node information includes quantized_1st_residual_value[j].

[0082] quantized_1st_residual_value[j] (where j is 0 to 2) represents the quantized value of the directional component of the predicted residual (difference information) between the coordinate values ​​of the target point to be encoded / decoded and the coordinate values ​​of the predicted point (predicted value).

[0083] For example, a three-dimensional data encoding device generates quantized_1st_residual_value[j] (where j is 0 or 1) by quantizing the predicted residuals of the horizontal angle component and the predicted residuals of the elevation angle component using a quantization step value. Information indicating the quantization step value is stored, for example, in the higher-level syntax of the bitstream (such as SPS, GPS, or slice header).

[0084] Furthermore, the three-dimensional data encoding device may store in the bitstream, in addition to quantized_1st_residual_value[j], the remainder component, which is the difference between the predicted residual before quantization and the predicted residual after quantization (quantized value). For example, this remainder component may be stored in the bitstream as 1st_residual_value[i]. Specifically, the remainder components of the horizontal angle and elevation angle may be stored in the bitstream as the 1st_residual_value of the horizontal angle and elevation angle, respectively.

[0085] This means that when encoding point cloud data obtained from a sensor whose direction changes at a constant speed, the three-dimensional data encoding device may be able to suppress the code amount of the predicted residual of the directional component by setting a quantization step value that matches the speed. Furthermore, in cases where the three-dimensional data device encodes point cloud data generated by acquiring the three-dimensional position of surrounding objects by rotating in one direction, such as with a laser sensor that performs rotational scanning such as LiDAR, the quantized value and residual component may be stored in the bitstream for one component in the same direction as the sensor's rotation direction (e.g., horizontal angle), while only the quantized value or only the predicted residual before quantization (1st_residual_value) may be stored in the bitstream for other directional components (e.g., elevation angle) and distance components.

[0086] 1st_residual_value[i] represents the predicted residual for each component (horizontal angle, elevation angle, distance, or x, y, z) of the position information of the target point. Note that if the residual components are stored in the bitstream as described above, 1st_residual_value[i] represents the residual component of the corresponding component.

[0087] The `gps_coordinate_trans_enabled_flag` flag indicates whether or not to perform a coordinate transformation of the position coordinates before or after encoding. If a coordinate transformation is performed (gps_coordinate_trans_enabled_flag=1), the 3D data encoding device converts the input Cartesian coordinate system position information to polar coordinate system position information before encoding. The 3D data decoding device then converts the decoded polar coordinate system position information back to Cartesian coordinate system position information before outputting it.

[0088] When a coordinate transformation is performed (gps_coordinate_trans_enabled_flag=1), the node information includes 2nd_residual_value[i]. 2nd_residual_value[i] indicates the difference between the position information in the Cartesian coordinate system and the position information in the polar coordinate system resulting from the coordinate transformation. The 3D data decoding device converts the decoded polar coordinate system position information back to the Cartesian coordinate system position information, and then restores the original Cartesian coordinate system position information by adding this difference to the converted Cartesian coordinate system position information.

[0089] Next, we will explain the method for selecting the context in the entropy coding and decoding processes of the prediction residuals. While the following explanation primarily focuses on the context selection method in a three-dimensional data encoding device, the same method applies to the context selection method in a three-dimensional data decoding device.

[0090] The three-dimensional data encoding device may determine the context (probability table) to be used for entropy coding (arithmetic coding) of 1st_residual_value[i] depending on quantized_1st_residual_value[j].

[0091] Here, the context (probability table) indicates the probability of a symbol (signal value) appearing. The probabilities are updated according to the processed symbols, and these updated probabilities are used for the arithmetic coding of subsequent signals. Furthermore, the correspondence between input and output values ​​in arithmetic coding is determined according to these probabilities.

[0092] Furthermore, the three-dimensional data encoding device may determine the context to be used for entropy encoding of the second component of 1st_residual_value[i], which is different from the first component, depending on the first component of the processed (encoded) 1st_residual_value[i]. Here, the first component is, for example, one of the horizontal angle, elevation angle, and distance in polar coordinates, and the second component is one of the horizontal angle, elevation angle, and distance other than the first component.

[0093] For example, when a three-dimensional data encoding device obtains the three-dimensional positions of surrounding objects centered on the position of a sensor such as a LiDAR and encodes the resulting point cloud using polar coordinates, it may select from multiple contexts the context used for arithmetic coding of the predicted residual of distance (1st_residual_value[i]) depending on at least one of the quantized values ​​(quantized_1st_residual_value[j]) of the predicted residual of the horizontal angle and the predicted residual of the elevation angle. For example, the three-dimensional data encoding device may switch the context used for arithmetic coding of the predicted residual of distance depending on whether the quantized value of the predicted residual of the horizontal angle is 0 or not.

[0094] Furthermore, the three-dimensional data encoding device may select from multiple contexts to use for arithmetic coding of the predicted residuals (1st_residual_value[i]) of the directional components (horizontal angle or elevation angle) depending on 1st_residual_value[i], which corresponds to the predicted residual of distance. For example, the three-dimensional data encoding device may switch the context used for arithmetic coding of the predicted residuals of the directional components (horizontal angle or elevation angle) depending on whether the absolute value of the predicted residual of distance is greater than a threshold. This threshold may be a predetermined fixed value or a variable value. If the threshold is a variable value, information indicating the threshold may be stored in the bitstream. For example, this information may be stored in an SPS, GPS, or slice header.

[0095] In other words, the three-dimensional data encoding device may switch the context used for entropy coding the predicted residual of the second component (1st_residual_value[i]) depending on the predicted residual of the quantized first component (quantized_1st_residual_value[j]). Here, the second component may be different from or the same as the first component. Note that if the second component is the same as the first component, for example, 1st_residual_value[i] represents the remainder component described above.

[0096] Furthermore, the three-dimensional data encoding device may switch the context used for entropy coding of the predicted residual (1st_residual_value[i]) of the second component, which is different from the first component, depending on the predicted residual (1st_residual_value[i]) of the first component. For example, one of the first and second components may be a directional component (horizontal angle or elevation angle), and the other may be a distance component.

[0097] Thus, a three-dimensional data encoding device may be able to improve encoding efficiency by determining the context used for arithmetic coding of subsequent prediction residuals based on the prediction residual or its quantized value, which is correlated with the likelihood of the intra-prediction or inter-prediction.

[0098] Furthermore, the three-dimensional data encoding device may determine the context used for entropy encoding of the 1st_residual_value[i] of the target point depending on whether intra-encoding mode or inter-encoding mode is used for encoding the target point (for example, whether intra_pred_flag is 1 or not).

[0099] Furthermore, the three-dimensional data encoding device may determine the context used for entropy encoding of the 1st_residual_value[i] of the second component of the target point, depending on whether intra-encoding mode or inter-encoding mode is used for encoding the first component of the target point. Here, the second component may be different from or the same as the first component.

[0100] Thus, a three-dimensional data encoding device may be able to improve encoding efficiency by using different contexts for intra-prediction and inter-prediction, where the distribution trends of prediction residuals differ.

[0101] Furthermore, the three-dimensional data encoding device may determine the context to be used for arithmetic encoding of the second component's 1st_residual_value[i] by combining some or all of the context determination methods, such as the above-mentioned quantized_1st_residual_value[j], the encoded first component's 1st_residual_value[i], or whether intra_pred_flag is 1 or not.

[0102] Furthermore, the three-dimensional data encoding device may combine some or all of the context determination methods, depending on the parameters of the other prediction method, with the above context determination method to determine the context to be used for arithmetic coding of 1st_residual_value[i]. The parameters of the other prediction method include, for example, pred_mode, inter_ref_frame_idx, or inter_red_point_idx.

[0103] In other words, the 3D data encoding device may determine the context based on pred_mode, for example, in intra-prediction, depending on whether or not some or all components of the coordinates of the parent node of the prediction tree or the immediately preceding encoded node are used to determine the predicted value. Alternatively, the 3D data encoding device may determine the context based on inter_ref_frame_idx, depending on which reference frame was used for inter-prediction. Furthermore, the 3D data encoding device may determine the context based on inter_red_point_idx, depending on which reference point was used for inter-prediction. By combining some or all of these methods, the 3D data encoding device may be able to select a context suitable for the characteristics of the prediction residuals, potentially further improving encoding efficiency.

[0104] Note that 1st_residual_value[i] may be encoded by dividing it into multiple syntax elements, such as the sign part and the absolute value part. In this case, the above context determination method may be applied to all syntax elements related to 1st_residual_value[i], or it may be applied only to some syntax elements, such as the syntax elements related to the absolute value part.

[0105] Figure 4 is a flowchart illustrating an example of the procedure for determining the context used for arithmetic coding of 1st_residual_value[i] in the syntax example shown in Figure 3.

[0106] First, the three-dimensional data encoding device obtains the intra_pred_flag (S101). Next, the three-dimensional data encoding device determines, based on the obtained intra_pred_flag, whether the prediction method (encoding mode) is intra-prediction (intra_pred_flag=1) or inter-prediction (intra_pred_flag=0) (S102).

[0107] If the prediction method is determined to be intra prediction (Yes in S102), the three-dimensional data encoding device sets the first value for selecting a context corresponding to intra prediction (intra encoding mode) to ctx_mode (S103). Furthermore, the three-dimensional data encoding device sets the threshold th_qphi to a first threshold corresponding to intra prediction (S104).

[0108] On the other hand, if the prediction method is determined to be interpretation (No in S102), the three-dimensional data encoding device sets a second value to ctx_mode for selecting a context corresponding to interpretation (intercoding mode) (S105). Furthermore, the three-dimensional data encoding device sets a second threshold corresponding to interpretation in the threshold th_qphi (S106). For example, the second value is different from the first value, and the second threshold is different from the first threshold.

[0109] Next, the three-dimensional data encoding device obtains the quantized_1st_residual_value[j] of the horizontal angle and sets the obtained quantized_1st_residual_value[j] of the horizontal angle to qphi (S107).

[0110] Next, the three-dimensional data encoding device determines whether the absolute value of qphi (abs(qphi)) is greater than the threshold th_qphi set in step S104 or S106 (S108). Based on this determination, the three-dimensional data encoding device determines the accuracy of the predicted coordinate values.

[0111] If the absolute value of qphi is greater than th_qphi (Yes in S108), the three-dimensional data encoding device sets the third value to ctx_qphi (S109). Here, the case where the absolute value of qphi is greater than th_qphi means that the probability of the predicted value is low, and the third value is used to select a context corresponding to the case where the probability of the predicted value is low.

[0112] On the other hand, if the absolute value of qphi is less than or equal to th_qphi (No in S108), the three-dimensional data encoding device sets the fourth value to ctx_qphi (S110). Here, the case where the absolute value of qphi is less than or equal to th_qphi means that the probability of the predicted value is higher than the case where the absolute value of qphi is greater than th_qphi, and the fourth value is used to select a context corresponding to the case where the probability of the predicted value is high.

[0113] Finally, the three-dimensional data encoding device selects a context to be used for arithmetic encoding of 1st_residual_value[i] according to the ctx_mode set in step S103 or step 105 and the ctx_qphi set in step S109 or step 110 (S111). For example, the three-dimensional data encoding device selects one of four contexts depending on the combination of ctx_mode and ctx_qphi.

[0114] This method may be applied to all components of the predicted residual 1st_residual_value[i], or it may be applied to only some components, such as the distance component or the direction component.

[0115] In step S108, if the absolute value of the predicted residual for the horizontal angle is small, the prediction is considered to be working well, and based on the assumption that the absolute value of the predicted residual for distance is also small, the accuracy of the predicted value is determined to be high when the absolute value of qphi is less than or equal to the threshold th_qphi. Here, in the case of inter-prediction, the predicted value is determined based on a point in a reference frame other than the target frame, so compared to intra-prediction, the absolute value of the predicted residual for distance tends to be small even when the predicted residual for the horizontal angle is large. For these reasons, it is desirable to use a value such as 0 or 1 as the first threshold, and a value such as 1 or 2, which is larger than the first threshold, as the second threshold.

[0116] As described above, by allowing the threshold th_qphi, used to determine the likelihood of a predicted value, to be set separately for intra-prediction and inter-prediction, which have different prediction characteristics, it is possible to select a more appropriate context for each. This may improve coding efficiency.

[0117] Furthermore, not all components disclosed using Figures 3 and 4 are always necessary, and the three-dimensional data encoding device may perform only some of the processing.

[0118] Furthermore, while the above mainly described the method for determining the context in arithmetic coding using a three-dimensional data encoding device, the method for determining the context in arithmetic decoding using a three-dimensional data decoding device is similar. The operation of the three-dimensional data decoding device can be described by replacing "coding" with "decoding" in the above explanation.

[0119] Furthermore, in step S108 above, it was determined whether the absolute value of qphi is greater than the threshold th_qphi. This determination is equivalent to determining whether -th_qphi ≤ qphi ≤ th_qphi is satisfied. In other words, this determination determines whether qphi is included in the numerical range where the upper limit is +th_qphi and the lower limit is -th_qphi. Note that when comparing the absolute value with the threshold, the center of the numerical range is zero, but a numerical range with a center other than zero may also be used.

[0120] Furthermore, if th_qphi is 0, the determination process in step S108 is equivalent to determining whether qphi is 0 or not. In other words, this determination determines whether qphi is a predetermined value or not. Note that when comparing the absolute value with a threshold of 0, this predetermined value is 0, but the predetermined value may be other than 0.

[0121] As described above, the encoding device (three-dimensional data encoding device) according to this embodiment performs the processing shown in Figure 5. The encoding device determines a numerical range based on whether intra-prediction or inter-prediction is used to encode the first information of the target three-dimensional point (S201), and switches between the first and second contexts used for entropy encoding of the first information based on whether the value of the second information of the target three-dimensional point is included in the determined numerical range (S202). For example, the encoding device selects the first context if the value of the second information of the target three-dimensional point is included in the determined numerical range, and selects the second context if the value of the second information of the target three-dimensional point is not included in the determined numerical range.

[0122] The relative magnitude of the value of the second piece of information to the prediction residual of the first piece of information may differ between the intra-prediction method and the inter-prediction method. Therefore, this embodiment changes the numerical range of the absolute value of the second piece of information used to determine context switching depending on whether the prediction method is the inter-prediction method or the intra-prediction method. In other words, this embodiment changes the numerical range depending on the accuracy of the prediction method. As a result, a context is selected according to the accuracy (or inaccuracy) of the prediction for each prediction method, thereby improving coding efficiency.

[0123] For example, in determining the numerical range (S201), the encoding device determines thresholds (e.g., th_qphi) to specify the upper and lower limits of the numerical range, and in switching (S202), it compares the determined thresholds with the absolute value of the second information to switch the context used for entropy coding of the first information. For example, the encoding device selects the first context if the absolute value of the second information is greater than the threshold, and selects the second context if the absolute value of the second information is less than the threshold.

[0124] According to this method, by comparing the threshold value with the absolute value of the second piece of information, it is possible to determine whether or not the second piece of information falls within a numerical range.

[0125] For example, in determining the numerical range (S201), if intra prediction is used to encode the first information, a first threshold is determined (e.g., S104 in Figure 4), and if inter prediction is used to encode the first information, a second threshold greater than the first threshold is determined (e.g., S106 in Figure 4).

[0126] In other words, this embodiment can increase the likelihood of selecting a context corresponding to the magnitude of the prediction residual by increasing the threshold when using the interpretation method, which is less accurate than the intraprediction method. However, there may be cases where the intraprediction method is also less accurate.

[0127] For example, the first threshold is 0, and the second threshold is an integer value greater than or equal to 1.

[0128] For example, the second piece of information shows the predicted residual of either the horizontal angle or the elevation angle of the target three-dimensional point, while the first piece of information shows the predicted residual of the distance of the target three-dimensional point.

[0129] According to this, when the predicted residual of distance depends on the absolute value of the horizontal or elevation angle, it is possible to increase the likelihood of selecting a context that corresponds to the magnitude of the predicted residual.

[0130] For example, the second piece of information shows the quantized value of one of the predicted residuals of the horizontal angle and elevation angle of the target three-dimensional point, while the first piece of information shows at least one predicted residual of the distance, horizontal angle, and elevation angle of the target three-dimensional point.

[0131] This increases the likelihood of selecting a context that corresponds to the magnitude of the predicted residual when at least one of the predicted residuals (distance, horizontal angle, and elevation angle) depends on the absolute value of the quantized value of the horizontal or elevation angle.

[0132] For example, the second piece of information represents the quantized value of the predicted residual of the horizontal angle of the target three-dimensional point.

[0133] This increases the likelihood of selecting a context that corresponds to the magnitude of the predicted residual when at least one of the predicted residuals (distance, horizontal angle, and elevation angle) depends on the absolute value of the quantized horizontal angle. Furthermore, the inventors have experimentally found that this combination has a significant effect in reducing the reduction of coding efficiency.

[0134] For example, in determining the numerical range (S201), if it is determined that intra-prediction will be used for the target three-dimensional point, a non-zero first threshold is determined. Note that the first threshold may be zero.

[0135] Furthermore, the decoding device (three-dimensional data decoding device) according to this embodiment performs the processing shown in Figure 6. The decoding device determines a numerical range based on whether intra-prediction or inter-prediction is used to decode the encoded first information of the target three-dimensional point (S211), and switches between the first and second contexts used for entropy decoding of the encoded first information based on whether the value of the decoded second information of the target three-dimensional point is included in the determined numerical range (S212). For example, the decoding device selects the first context if the value of the second information of the target three-dimensional point is included in the determined numerical range, and selects the second context if the value of the second information of the target three-dimensional point is not included in the determined numerical range.

[0136] The relative magnitude of the value of the second piece of information to the prediction residual of the first piece of information may differ between the intra-prediction method and the inter-prediction method. Therefore, this embodiment changes the numerical range in which the decoded value of the second piece of information, used to determine context switching, is likely to be included, based on whether the prediction method is the inter-prediction method or the intra-prediction method. In other words, this embodiment changes the numerical range according to the accuracy of the prediction method. As a result, a context is selected according to the accuracy (or inaccuracy) of the prediction for each prediction method, which reduces the amount of data in the bitstream (encoded data). Therefore, the amount of data handled by the decoding device can be reduced.

[0137] For example, in determining the numerical range (S211), the decoder determines a threshold (e.g., th_qphi) to specify the upper and lower limits of the numerical range, and in switching (S212), it compares the determined threshold with the absolute value of the decoded second information and switches the context used for decoding the entropy of the encoded first information. For example, the decoder selects the first context if the absolute value of the second information is greater than the threshold, and selects the second context if the absolute value of the second information is less than the threshold.

[0138] According to this method, by comparing the threshold value with the absolute value of the second piece of information, it is possible to determine whether or not the second piece of information falls within a numerical range.

[0139] For example, in determining the numerical range (S211), if intra prediction is used to decode the encoded first information, a first threshold is determined (e.g., S104 in Figure 4), and if inter prediction is used to decode the encoded first information, a second threshold greater than the first threshold is determined (e.g., S106 in Figure 4).

[0140] In the interprediction method, the relative magnitude of the value of the second information (e.g., the prediction residual) to the prediction residual of the first information may be larger than in the intraprediction method. Therefore, this embodiment increases the likelihood that a context suitable for the magnitude of the prediction residual of the first information will be selected by increasing the threshold when the interprediction method is used. However, even in the intraprediction method, the relative magnitude of the value of the second information to the prediction residual of the first information may be large.

[0141] For example, if the first threshold is 0, the second threshold is an integer value greater than or equal to 1.

[0142] For example, the decoded second piece of information represents the predicted residual of either the horizontal angle or the elevation angle of the target three-dimensional point, and the encoded first piece of information is generated by encoding the predicted residual of the distance of the target three-dimensional point.

[0143] According to this, when the predicted residual of distance depends on the absolute value of the horizontal or elevation angle, it is possible to increase the likelihood of selecting a context that corresponds to the magnitude of the predicted residual.

[0144] For example, the decoded second information represents the quantized value of one of the predicted residuals of the horizontal angle and elevation angle of the target three-dimensional point, and the encoded first information is generated by encoding at least one of the predicted residuals of the distance, horizontal angle, and elevation angle of the target three-dimensional point.

[0145] This increases the likelihood of selecting a context that corresponds to the magnitude of the predicted residual when at least one of the predicted residuals (distance, horizontal angle, and elevation angle) depends on the absolute value of the quantized value of the horizontal or elevation angle.

[0146] For example, the decoded second piece of information represents the quantized value of the predicted residual of the horizontal angle of the target three-dimensional point.

[0147] This increases the likelihood of selecting a context that corresponds to the magnitude of the predicted residual when at least one of the predicted residuals (distance, horizontal angle, and elevation angle) depends on the absolute value of the quantized horizontal angle. Furthermore, the inventors of this application have experimentally found that this combination is highly effective in improving coding efficiency and reducing the amount of data handled by the decoder.

[0148] For example, in determining the numerical range (S211), if it is determined that intra-prediction will be used for the target three-dimensional point, a non-zero first threshold (e.g., a value of 1) is determined. Note that the first threshold may be zero. Also, if the first threshold is 1, the second threshold may be an integer value of 2 or greater.

[0149] The three-dimensional data encoding device (encoding device) and three-dimensional data decoding device (decoding device), etc., relating to embodiments and modifications of the present disclosure have been described above, but the present disclosure is not limited to these embodiments.

[0150] Furthermore, each processing unit included in the three-dimensional data encoding device and the three-dimensional data decoding device, etc., according to the above embodiment is typically implemented as an integrated circuit (LSI). These may be individually integrated into a single chip, or some or all of them may be integrated into a single chip.

[0151] Furthermore, integrated circuit implementation is not limited to LSIs; it may also be achieved using dedicated circuits or general-purpose processors. Field-Programmable Gate Arrays (FPGAs), which can be programmed after LSI manufacturing, or reconfigurable processors, which allow for the reconfiguration of the connections and settings of circuit cells within the LSI, may also be used.

[0152] Furthermore, in each of the above embodiments, each component may be implemented by being composed of dedicated hardware or by executing a software program suitable for each component. Each component may also be implemented by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0153] Furthermore, this disclosure may be implemented as a three-dimensional data encoding method (encoding method) or a three-dimensional data decoding method (decoding method), etc., performed by a three-dimensional data encoding device (encoding device) and a three-dimensional data decoding device (decoding device), etc.

[0154] Furthermore, the division of functional blocks in the block diagram is just one example; multiple functional blocks can be implemented as a single functional block, a single functional block can be divided into multiple parts, or some functions can be moved to other functional blocks. In addition, the functions of multiple functional blocks with similar functions can be processed in parallel or time-sharing by a single piece of hardware or software.

[0155] Furthermore, the order in which each step in the flowchart is performed is illustrative for the purpose of specifically illustrating this disclosure, and may be in a different order. Also, some of the above steps may be performed simultaneously (in parallel) with other steps.

[0156] Although a three-dimensional data encoding device and a three-dimensional data decoding device, etc., relating to one or more embodiments have been described above based on embodiments, this disclosure is not limited to these embodiments. Without departing from the spirit of this disclosure, various modifications that a person skilled in the art can conceive of may be applied to these embodiments, and forms constructed by combining components from different embodiments may also be included within the scope of one or more embodiments. [Industrial applicability]

[0157] This disclosure is applicable to three-dimensional data encoding devices and three-dimensional data decoding devices. [Explanation of Symbols]

[0158] 100 3D data encoding device 102 Subtraction Unit 103 Quantization section 104 Entropy coding unit 105, 202 Inverse quantization section 106, 203 Addition section 108, 110, 205, 207 buffers 109, 206 Intra Prediction Unit 111 Motion detection compensation unit 112, 209 Interpretation Unit 113, 210 Switching section 200 Three-dimensional data decoding device 201 Entropy Decoder 208 Motion compensation unit

Claims

1. The numerical range is determined based on whether intra-prediction or inter-prediction is used to decode the encoded first information of the target three-dimensional point. Based on whether the decoded value of the second information of the target three-dimensional point falls within the determined numerical range, the context used for entropy decoding of the encoded first information is switched between the first and second contexts. Decryption method.

2. In the above determination, thresholds are determined to specify the upper and lower limits of the numerical range. In the aforementioned switching, the determined threshold is compared with the absolute value of the decoded second information, and the context used for the entropy decoding of the encoded first information is switched. The decoding method according to claim 1.

3. In the aforementioned decision, When the intra prediction is used to decode the encoded first information, the first threshold is determined. When the inter prediction is used to decode the encoded first information, a second threshold greater than the first threshold is determined. The decoding method according to claim 2.

4. The first threshold is 0, The second threshold is an integer value greater than or equal to 1. The decoding method according to claim 3.

5. The decoded second information indicates the predicted residual of either the horizontal angle or the elevation angle of the target three-dimensional point. The encoded first information is generated by encoding the predicted residual of the distance of the target three-dimensional point. The decoding method according to claim 1.

6. The decoded second information indicates the quantized value of the predicted residual of either the horizontal angle or the elevation angle of the target three-dimensional point. The encoded first information is generated by encoding the predicted residual of at least one of the distance, horizontal angle, and elevation angle of the target three-dimensional point. The decoding method according to claim 1.

7. The decoded second information indicates the quantized value of the predicted residual of the horizontal angle of the target three-dimensional point. The decoding method according to claim 6.

8. In the aforementioned decision, If it is determined that the intra prediction will be used for the target three-dimensional point, the first non-zero threshold is determined. The decoding method according to claim 3.

9. The numerical range is determined based on whether intra-prediction or inter-prediction is used to encode the first information of the target three-dimensional point. Based on whether the value of the second information of the target three-dimensional point falls within the determined numerical range, the context used for entropy coding the first information is switched between the first and second contexts. Encoding method.

10. In the above determination, thresholds are determined to specify the upper and lower limits of the numerical range. In the aforementioned switching, the determined threshold is compared with the absolute value of the second information, and the context used for entropy coding of the first information is switched. The encoding method according to claim 9.

11. In the aforementioned decision, When the intra prediction is used to encode the first information, the first threshold is determined. When the inter prediction is used to encode the first information, a second threshold greater than the first threshold is determined. The encoding method according to claim 10.

12. The first threshold is 0, The second threshold is an integer value greater than or equal to 1. The encoding method according to claim 11.

13. The second piece of information indicates the predicted residual of either the horizontal angle or the elevation angle of the target three-dimensional point. The first information indicates the predicted residual of the distance of the target three-dimensional point. The encoding method according to claim 9.

14. The second piece of information indicates the quantized value of the predicted residual of either the horizontal angle or the elevation angle of the target three-dimensional point. The first information indicates the predicted residual of at least one of the distance, horizontal angle, and elevation angle of the target three-dimensional point. The encoding method according to claim 9.

15. The second piece of information indicates the quantized value of the predicted residual of the horizontal angle of the target three-dimensional point. The encoding method according to claim 14.

16. In the aforementioned decision, If it is determined that the intra prediction will be used for the target three-dimensional point, the first non-zero threshold is determined. The encoding method according to claim 11.

17. Processor and Equipped with memory, The processor uses the memory to: The numerical range is determined based on whether intra-prediction or inter-prediction is used to decode the encoded first information of the target three-dimensional point. Based on whether the decoded value of the second information of the target three-dimensional point falls within the determined numerical range, the context used for entropy decoding of the encoded first information is switched between the first and second contexts. Decoding device.

18. Processor and Equipped with memory, The processor uses the memory to: The numerical range is determined based on whether intra-prediction or inter-prediction is used to encode the first information of the target three-dimensional point. Based on whether the value of the second information of the target three-dimensional point falls within the determined numerical range, the context used for entropy coding the first information is switched between the first and second contexts. Encoding device.

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