Method and apparatus for point cloud coding

An apparatus for point cloud coding, comprising:

• processing circuitry configured to:
• receive point cloud data of a point cloud;
• derive an octree structure of the point cloud based on the point cloud data, nodes in the octree structure corresponding to three dimensional (3D) partitions of a space of the point cloud, sizes of the nodes being associated with sizes of the corresponding 3D partitions, the nodes in the octree structure including
• first nodes having first sizes larger than a threshold node size for coding order change, and
• second nodes having second sizes equal to or smaller than the threshold node size for coding order change, the second nodes being arranged into one or more sub octrees;
• generate a sequence of occupancy codes for the nodes in the octree structure of the point cloud, the sequence of occupancy codes includes:
• a first portion of the sequence of occupancy codes for the first nodes arranged according to a first coding order, and
• a second portion of the sequence of occupancy codes including one or more subsets of occupancy codes for the one or more sub octrees respectively arranged according to a second coding order, the second coding order being different from the first coding order;
• encode the sequence of occupancy codes into encoded data;
• and
• generate a coded bitstream that includes the encoded data.

A non-transitory computer-readable medium storing instructions which when executed by a computer for video decoding cause the computer to perform:

• receiving point cloud data of a point cloud;
• deriving an octree structure of the point cloud based on the point cloud data, nodes in the octree structure corresponding to three dimensional (3D) partitions of a space of the point cloud, sizes of the nodes being associated with sizes of the corresponding 3D partitions, the nodes in the octree structure including
• first nodes having first sizes larger than a threshold node size for coding order change, and
• second nodes having second sizes equal to or smaller than the threshold node size for coding order change, the second nodes being arranged into one or more sub octrees;
• generating a sequence of occupancy codes for the nodes in the octree structure of the point cloud, the sequence of occupancy codes includes:
• a first portion of the sequence of occupancy codes for the first nodes arranged according to a first coding order, and
• a second portion of the sequence of occupancy codes including one or more subsets of occupancy codes for the one or more sub octrees respectively arranged according to a second coding order, the second coding order being different from the first coding order;
• encoding the sequence of occupancy codes into encoded data;
• and
• generating a coded bitstream that includes the encoded data.