Method and apparatus for geometry merge mode for point cloud coding

1. A method of a geometry merge mode for point cloud coding (PCC), the method being performed by at least one processor, and the method comprising:

determining a maximum depth of an octree partition and a minimum depth of the octree partition where the geometry merge mode is permitted;

obtaining a candidate node of the octree partition of a point cloud, for a current node of the octree partition, the current node being currently-coded, and the candidate node being previously-coded, wherein the current node is at a depth between the maximum depth and the minimum depth where the geometry merge mode is permitted;

obtaining an occupancy code of the obtained candidate node;

constructing a candidate list comprising the obtained occupancy code of the candidate node;

obtaining an occupancy code of the current node, based on the constructed candidate list; and

performing the PCC, based on the obtained occupancy code of the current node.

2. The method of claim 1 , wherein the candidate node is spatially adjacent to the current node and is in a same depth of the octree partition as the current node.

3. The method of claim 1 , wherein the candidate node is predetermined, is spatially non-adjacent to the current node and is in a same depth of the octree partition as the current node.

4. The method of claim 1 , wherein the candidate node is a parent node or a grandparent node of the current node.

5. The method of claim 1 , wherein the candidate node is in a previously-coded frame before a currently-coded frame comprising the current node.

6. The method of claim 1 , wherein the candidate node is obtained from a predetermined table.

7. The method of claim 1 , further comprising determining whether a flag indicates that the geometry merge mode is enabled,

wherein the candidate node is obtained based on the flag being determined to indicate that the geometry merge mode is enabled.

8. The method of claim 7 , wherein the candidate list is constructed to have a predetermined maximum size, and

the geometry merge mode is enabled for one or more predetermined depths of the octree partition.

9. The method of claim 1 , further comprising:

determining whether a flag indicates a difference between the obtained occupancy code of the current node and a final occupancy code of the current node is enabled; and

based on the flag being determined to indicate that the difference is enabled, modifying the obtained occupancy code of the current node,

wherein the PCC is performed based on the modified occupancy code of the current node.

10. An apparatus for a geometry merge mode for point cloud coding (PCC), the apparatus comprising:

at least one memory configured to store program code; and

at least one processor configured to read the program code and operate as instructed by the program code, the program code comprising:

depth determining code configured to cause the at least one processor to determine a maximum depth of an octree partition and a minimum depth of the octree partition where the geometry merge mode is permitted;

first obtaining code configured to cause the at least one processor to obtain a candidate node of the octree partition of a point cloud, for a current node of the octree partition, the current node being currently-coded, and the candidate node being previously-coded, wherein the current node is at a depth between the maximum depth and the minimum depth where the geometry merge mode is permitted;

second obtaining code configured to cause the at least one processor to obtain an occupancy code of the obtained candidate node;

constructing code configured to cause the at least one processor to construct a candidate list comprising the obtained occupancy code of the candidate node;

third obtaining code configured to cause the at least one processor to obtain an occupancy code of the current node, based on the constructed candidate list; and

performing code configured to cause the at least one processor to perform the PCC, based on the obtained occupancy code of the current node.

11. The apparatus of claim 10 , wherein the candidate node is spatially adjacent to the current node and is in a same depth of the octree partition as the current node.

12. The apparatus of claim 10 , wherein the candidate node is predetermined, is spatially non-adjacent to the current node and is in a same depth of the octree partition as the current node.

13. The apparatus of claim 10 , wherein the candidate node is a parent node or a grandparent node of the current node.

14. The apparatus of claim 10 , wherein the candidate node is in a previously-coded frame before a currently-coded frame comprising the current node.

15. The apparatus of claim 10 , wherein the candidate node is obtained from a predetermined table.

16. The apparatus of claim 10 , further comprising determining code configured to cause the at least one processor to determine whether a flag indicates that the geometry merge mode is enabled,

wherein the candidate node is obtained based on the flag being determined to indicate that the geometry merge mode is enabled.

17. The apparatus of claim 16 , wherein the candidate list is constructed to have a predetermined maximum size, and

the geometry merge mode is enabled for one or more predetermined depths of the octree partition.

18. The apparatus of claim 10 , further comprising:

determining code configured to cause the at least one processor to determine whether a flag indicates a difference between the obtained occupancy code of the current node and a final occupancy code of the current node is enabled; and

modifying code configured to cause the at least one processor to, based on the flag being determined to indicate that the difference is enabled, modify the obtained occupancy code of the current node,

wherein the PCC is performed based on the modified occupancy code of the current node.

19. A non-transitory computer-readable medium storing instructions that, when executed by at least one processor of an apparatus for a geometry merge mode for point cloud coding (PCC), cause the at least one processor to:

determining a maximum depth of an octree partition and a minimum depth of the octree partition where the geometry merge mode is permitted;

obtain a candidate node of the octree partition of a point cloud, for a current node of the octree partition, the current node being currently-coded, and the candidate node being previously-coded, wherein the current node is at a depth between the maximum depth and the minimum depth where the geometry merge mode is permitted;

obtain an occupancy code of the obtained candidate node;

construct a candidate list comprising the obtained occupancy code of the candidate node;

obtain an occupancy code of the current node, based on the constructed candidate list; and

perform the PCC, based on the obtained occupancy code of the current node.

20. The non-transitory computer-readable medium of claim 19 , wherein the instructions further cause the at least one processor to determine whether a flag indicates that the geometry merge mode is enabled, and

the candidate node is obtained based on the flag being determined to indicate that the geometry merge mode is enabled.