A method of encoding point cloud data using a planar coding mode is disclosed. The planar coding mode may be signaled using a planar mode flag to signal that a current volume is planar. A volume is planar if all of its occupied child nodes are on one side of a plane bisecting the volume. A planar position flag may signal which side of the volume is occupied. Volume data for already-coded occupied volumes of the point cloud is tracked using a data structure stored in memory. Entropy coding may be used to code the planar mode flag and/or the planar position flag. Context determination for coding may take into account a distance between the volume and a closest already-coded occupied volume among those tracked already-coded occupied volumes that have a same index in the data structure as the current volume.

A method of encoding point cloud data using a planar coding mode is disclosed. The planar coding mode may be signaled using a planar mode flag to signal that a current volume is planar. A volume is planar if all of its occupied child nodes are on one side of a plane bisecting the volume. A planar position flag may signal which side of the volume is occupied. Volume data for already-coded occupied volumes of the point cloud is tracked using a data structure stored in memory. Entropy coding may be used to code the planar mode flag and/or the planar position flag. Context determination for coding may take into account a distance between the volume and a closest already-coded occupied volume among those tracked already-coded occupied volumes that have a same index in the data structure as the current volume.

An example device includes one or more processors, and memory storing instructions that when executed by the processors, cause the processors to receive points that represent a point cloud in three-dimensional space, and generate a data structure representing the point cloud. Generating the data structure includes encoding a position of each point in each dimension as a sequence of bits according to a tree data structure; partitioning each of the sequences into two or more portions according to a scaling depth; determining that a subset of the points is spatially isolated from a remainder of the points; quantizing each of the portions associated with the subset of the points according to a first quantization step size; quantizing each of the portions associated with the remainder of the points according to a second quantization step size; and including the quantized portions in the data structure.

A three-dimensional data encoding method includes: shifting point cloud data indicating three-dimensional positions in a three-dimensional space by a first shift amount; dividing the point cloud data into pieces of sub point cloud data; shifting each of the pieces of sub point cloud data by a second shift amount based on a position of one of the subspaces that includes the sub point cloud data, the pieces of sub point cloud data being included in the point cloud data shifted by the first shift amount; and encoding the pieces of sub point cloud data shifted, to generate a bitstream. The bitstream includes first shift information for calculating the first shift amount, and pieces of second shift information each for calculating a corresponding one of second shift amounts by which the pieces of sub point cloud data are shifted and each of which is the second shift amount.

Disclosed is a decoding method for decoding encoded data obtained by encoding a cube that includes three-dimensional point cloud data. The decoding method includes a step of obtaining point occupation states of solids obtained after division in one direction, from the encoded data, wherein the direction of the division is determined based on correlation among the point occupation states of the solids after the division. Another decoding method and a decoding apparatus are also disclosed.

Disclosed is a decoding method for decoding encoded data obtained by encoding a cube that includes three-dimensional point cloud data. The decoding method includes a step of obtaining point occupation states of solids obtained after division in one direction, from the encoded data, wherein the direction of the division is determined based on correlation among the point occupation states of the solids after the division. Another decoding method and a decoding apparatus are also disclosed.

A three-dimensional data encoding method includes encoding information of a current node included in an N-ary tree structure of three-dimensional points included in three-dimensional data, where N is an integer greater than or equal to 2. In the encoding, first information is encoded, the first information indicating a range for one or more referable neighboring nodes among neighboring nodes spatially neighboring the current node, and the current node is encoded with reference to a neighboring node within the range.

A method for point cloud decoding includes receiving a bitstream. The method also includes decoding the bitstream into multiple frames that include pixels. Certain pixels of the multiple frames correspond to points of a three-dimensional (3D) point cloud. The multiple frames include a first set of frames that represent locations of the points of the 3D point cloud and a second set of frames that represent attribute information for the points of the 3D point cloud. The method further includes reconstructing the 3D point cloud based on the first set of frames. Additionally, the method includes identifying a first portion of the points of the reconstructed 3D point cloud based at least in part on a property associated with the multiple frames. The method also includes modifying a portion of the attribute information. The portion of the attribute information that is modified corresponds to the first portion of the points.

Technology for improving coding efficiency by performing a block split suitable for picture coding and decoding is provided. A picture decoding device includes a spatial candidate derivation unit configured to derive a spatial candidate from inter prediction information of a block neighboring a decoding target block and register the derived spatial candidate as a candidate in a first candidate list, a history-based candidate derivation unit configured to generate a second candidate list by adding a history-based candidate included in a history-based candidate list as a candidate to the first candidate list, a candidate selection unit configured to select a selection candidate from candidates included in the second candidate list; and an inter prediction unit configured to perform inter prediction using the selection candidate. The history-based candidate derivation unit switches between whether or not a history-based candidate overlapping a candidate included in the first candidate list is added in accordance with a prediction mode.

A three-dimensional data encoding method includes: extracting, from first three-dimensional data, second three-dimensional data having an amount of a feature greater than or equal to a threshold; and encoding the second three-dimensional data to generate first encoded three-dimensional data. For example, the three-dimensional data encoding method may further include encoding the first three-dimensional data to generate the second encoded three-dimensional data.