Hybrid coding order for point cloud coding

1. A method for point cloud decoding, comprising:

receiving a coded bitstream for a point cloud, the coded bitstream including encoded data for nodes in an octree structure for the point cloud, the nodes in the octree structure corresponding to three dimensional (3D) partitions of a space of the point cloud, node sizes of the nodes being associated with sizes of the corresponding 3D partitions of the nodes;

decoding, from the coded bitstream, a first set of occupancy codes for a first set of nodes in the nodes using one of a breadth first coding order or a depth first coding order;

based on a change of coding order signal included in the coded bitstream, changing from decoding using the one of the breadth first coding order or the depth first coding order to decoding, from the coded bitstream, a second set of occupancy codes for a second set of nodes in the nodes using the other of the breadth first coding order or the depth first coding order; and

reconstructing the octree structure based on at least the first set of occupancy codes and the second set of occupancy codes,

wherein first node sizes of the first set of nodes are greater than or equal to a threshold node size, and second node sizes of the second set of nodes are less than the threshold node size.

2. The method of claim 1 , wherein the second set of nodes form a first sub octree with a first root node, and the method further comprises:

decoding, from the coded bitstream, a third set of occupancy codes for a third set of nodes in the nodes, the third set of nodes forming a second sub octree with a second root node, the first root node and the second root node being of a same node size.

3. The method of claim 2 , wherein:

the decoding the second set of occupancy codes for the second set of nodes of the first sub octree is in parallel with the decoding the third set of occupancy codes for the third set of nodes of the second sub octree.

4. The method of claim 2 , wherein:

the decoding the second set of occupancy codes includes decoding, based on the other of the breadth first coding order or the depth first coding order, the second set of occupancy codes for the second set of nodes in the first sub octree; and

the decoding the third set of occupancy codes includes decoding, based on the one of the breadth first coding order or the depth first coding order, the third set of occupancy codes for the third set of nodes in the second sub octree.

5. The method of claim 4 , further comprising:

decoding, from the coded bitstream, a first index that is indicative of the other of the breadth first coding order or the depth first coding order for the first sub octree; and

decoding, from the coded bitstream, the change of coding order signal comprising a second index that is indicative of the one of the breadth first coding order or the depth first coding order for the second sub octree.

6. The method of claim 1 , further comprising:

determining the threshold node size based on coded information in the coded bitstream for the point cloud.

7. An apparatus for point cloud encoding, comprising processing circuitry configured to:

generate a coded bitstream for a point cloud, the coded bitstream including encoded data for nodes in an octree structure for the point cloud, the nodes in the octree structure corresponding to three dimensional (3D) partitions of a space of the point cloud, node sizes of the nodes being associated with sizes of the corresponding 3D partitions of the nodes, the coded bitstream is generated by

encoding, in the coded bitstream, a first set of occupancy codes for a first set of nodes in the nodes using one of a breadth first coding order or a depth first coding order;

including a change of coding order signal in the coded bitstream, and changing from encoding using the one of the breadth first coding order or the depth first coding order to encode, in the coded bitstream, a second set of occupancy codes for a second set of nodes in the nodes using the other of the breadth first coding order or the depth first coding order; and

encode the octree structure based on at least the first set of occupancy codes and the second set of occupancy codes,

wherein first node sizes of the first set of nodes are greater than or equal to a threshold node size, and second node sizes of the second set of nodes are less than the threshold node size.

8. The apparatus of claim 7 , wherein the second set of nodes form a first sub octree with a first root node, the processing circuitry is configured to:

encode, in the coded bitstream, a third set of occupancy codes for a third set of nodes in the nodes, the third set of nodes forming a second sub octree with a second root node, the first root node and the second root node being of a same node size.

9. The apparatus of claim 8 , wherein:

the second set of occupancy codes for the second set of nodes of the first sub octree is encoded in parallel with the third set of occupancy codes for the third set of nodes of the second sub octree.

10. The apparatus of claim 8 , wherein the processing circuitry is configured to:

encode, based on the other of the breadth first coding order or the depth first coding order, the second set of occupancy codes for the second set of nodes in the first sub octree; and

encode, based on the one of the breadth first coding order or the depth first coding order, the third set of occupancy codes for the third set of nodes in the second sub octree.

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

encoding, in the coded bitstream, a first index that is indicative of the other of the breadth first coding order or the depth first coding order for the first sub octree; and

encoding, in the coded bitstream, the change of coding order signal comprising a second index that is indicative of the one of the breadth first coding order or the depth first coding order for the second sub octree.

12. The apparatus of claim 7 , wherein the processing circuitry is configured to:

indicate the threshold node size in the coded bitstream for the point cloud.

13. A method of processing visual media data, the method comprising:

processing a bitstream of the visual media data according to a format rule, wherein

the bitstream includes encoded data for nodes in an octree structure for a point cloud, the nodes in the octree structure corresponding to three dimensional (3D) partitions of a space of the point cloud, node sizes of the nodes being associated with sizes of the corresponding 3D partitions of the nodes,

the format rule specifies that

a first set of occupancy codes for a first set of nodes in the nodes is decoded from the bitstream using one of a breadth first coding order or a depth first coding order;

based on a change of coding order signal included in the bitstream, decoding using the one of the breadth first coding order or the depth first coding order is changed to decoding, from the bitstream, a second set of occupancy codes for a second set of nodes in the nodes using the other of the breadth first coding order or the depth first coding order,

the octree structure is reconstructed based on at least the first set of occupancy codes and the second set of occupancy codes, and

first node sizes of the first set of nodes are greater than or equal to a threshold node size, and second node sizes of the second set of nodes are less than the threshold node size.