Method and apparatus for point cloud compression

1. A method for point cloud coding in a decoder, comprising:

decoding syntax information of a bounding box of a point cloud from a coded bitstream, the syntax information indicating an octree partitioning structure for the bounding box of the point cloud;

determining whether the syntax information indicates that parallel decoding is to be performed on occupancy codes of nodes in a range of one or more partitioning depths in the octree partitioning structure;

performing the parallel decoding on the occupancy codes of the nodes in response to the syntax information indicating that the parallel decoding is to be performed on the occupancy codes of the nodes in the range of the one or more partitioning depths in the octree partitioning structure; and

reconstructing the bounding box based on the occupancy codes of the nodes.

2. The method of claim 1 , wherein the determining further comprises:

determining whether the syntax information indicates that the occupancy codes of the nodes in the range of the one or more partitioning depths in the octree partitioning structure are to be decoded in parallel based on one of a signaled flag and a minimum partitioning depth at which the parallel decoding is to be performed.

3. The method of claim 2 , wherein the performing further comprises:

performing the parallel decoding on the occupancy codes of the nodes based on the minimum partitioning depth and a maximum partitioning depth at which the parallel decoding is to be performed, the maximum partitioning depth being equal to or less than a maximum partitioning depth of the octree partitioning structure.

4. The method of claim 1 , wherein the performing further comprises:

determining, in the coded bitstream, a sub-bitstream for each of the one or more partitioning depths based on a bitstream offset corresponding to each of the one or more partitioning depths; and

performing the parallel decoding on the sub-bitstreams of the one or more partitioning depths.

5. The method of claim 4 , wherein the bitstream offset corresponding to each of the one or more partitioning depths is included in the syntax information.

6. The method of claim 1 , wherein the performing further comprises:

performing the parallel decoding on the occupancy codes of the nodes in the range of the one or more partitioning depths based on context variables of the occupancy codes.

7. The method of claim 6 , further comprising:

determining initial probabilities of the context variables of the occupancy codes of the nodes as one or more predefined values.

8. The method of claim 6 , further comprising:

determining initial probabilities of the context variables of the occupancy codes of the nodes based on probabilities of context variables of occupancy codes of parent nodes of a plurality of nodes, the plurality of nodes being in a minimum partitioning depth at which the parallel decoding is to be performed.

9. The method of claim 6 , further comprising:

determining initial probabilities of the context variables of the occupancy codes of the nodes based on probabilities of context variables of occupancy codes of a subset of parent nodes of the nodes.

10. An apparatus for point cloud coding, comprising processing circuitry configured to:

decode syntax information of a bounding box of a point cloud from a coded bitstream, the syntax information indicating an octree partitioning structure for the bounding box of the point cloud;

determine whether the syntax information indicates that parallel decoding is to be performed on occupancy codes of nodes in a range of one or more partitioning depths in the octree partitioning structure;

perform the parallel decoding on the occupancy codes of the nodes in response to the syntax information indicating that the parallel decoding is to be performed on the occupancy codes of the nodes in the range of the one or more partitioning depths in the octree partitioning structure; and

reconstruct the bounding box based on the occupancy codes of the nodes.

11. The apparatus of claim 10 , wherein the processing circuitry is further configured to:

determine whether the syntax information indicates that the occupancy codes of the nodes in the range of the one or more partitioning depths in the octree partitioning structure are to be decoded in parallel based on one of a signaled flag and a minimum partitioning depth at which the parallel decoding is to be performed.

12. The apparatus of claim 11 , wherein the processing circuitry is further configured to:

perform the parallel decoding on the occupancy codes of the nodes based on the minimum partitioning depth and a maximum partitioning depth at which the parallel decoding is to be performed, the maximum partitioning depth being equal to or less than a maximum partitioning depth of the octree partitioning structure.

13. The apparatus of claim 10 , wherein the processing circuitry is further configured to:

determine, in the coded bitstream, a sub-bitstream for each of the one or more partitioning depths based on a bitstream offset corresponding to each of the one or more partitioning depths; and

perform the parallel decoding on the sub-bitstreams of the one or more partitioning depths.

14. The apparatus of claim 13 , wherein the bitstream offset corresponding to each of the one or more partitioning depths is included in the syntax information.

15. The apparatus of claim 10 , wherein the processing circuitry is further configured to:

perform the parallel decoding on the occupancy codes of the nodes in the range of the one or more partitioning depths based on context variables of the occupancy codes.

16. The apparatus of claim 15 , wherein the processing circuitry is further configured to:

determine initial probabilities of the context variables of the occupancy codes of the nodes as one or more predefined values.

17. The apparatus of claim 15 , wherein the processing circuitry is further configured to:

determine initial probabilities of the context variables of the occupancy codes of the nodes based on probabilities of context variables of occupancy codes of parent nodes of a plurality of nodes, the plurality of nodes being in a minimum partitioning depth at which the parallel decoding is to be performed.

18. The apparatus of claim 15 , wherein the processing circuitry is further configured to:

determine initial probabilities of the context variables of the occupancy codes of the nodes based on probabilities of context variables of occupancy codes of a subset of parent nodes of the nodes.

19. A non-transitory computer-readable medium storing instructions which when executed by a computer for point cloud coding cause the computer to perform:

decoding syntax information of a bounding box of a point cloud from a coded bitstream, the syntax information indicating an octree partitioning structure for the bounding box of the point cloud;

determining whether the syntax information indicates that a parallel decoding is to be performed on occupancy codes of nodes in a range of one or more partitioning depths in the octree partitioning structure;

performing the parallel decoding on the occupancy codes of the nodes in response to the syntax information indicating that the parallel decoding is to be performed on the occupancy codes of the nodes in the range of the one or more partitioning depths in the octree partitioning structure; and

reconstructing the bounding box based on the occupancy codes of the nodes.

20. The non-transitory computer-readable medium of claim 19 , wherein the stored instructions cause the computer to perform:

determining whether the syntax information indicates that the occupancy codes of the nodes in the range of the one or more partitioning depths in the octree partitioning structure are to be decoded in parallel based on one of a signaled flag and a minimum partitioning depth at which the parallel decoding is to be performed.