Implicit quadtree or binary-tree geometry partition for point cloud coding

1. A method of point cloud processing, comprising:

receiving a first syntax element in a bitstream corresponding to a sequence of coded point cloud frames, the first syntax element indicating whether implicit geometry partition is enabled for the sequence of coded point cloud frames;

determining the implicit geometry partition is enabled for the sequence of coded point cloud frames based on the first syntax element; and

reconstructing an octree representing a geometry of points in a bounding box of a slice in a coded point cloud frame in the sequence of coded point cloud frames based on the implicit geometry partition being determined to be enabled for the sequence of coded point cloud frames, a partition type being selected from a quadtree (QT) partition type in a three-dimensional (3D) space, a binary tree (BT) partition type in the 3D space, and an octree (OT) partition type in the 3D space for partitioning a current node of the octree in the implicit geometry partition.

2. The method of claim 1 , further comprising:

determining two parameters are signaled based on the implicit geometry partition being determined to be enabled for the sequence of coded point cloud frames, the two parameters including

a maximal number of QT and BT partitions performed before OT partitions, and

a minimal size of QT and BT partitions that prevents QT and BT partitions of a node when all dimensions of the node are smaller than or equal to the minimal size.

3. The method of claim 1 , further comprising:

determining syntax elements indicating 3D sizes of the bounding box of the slice of the coded point cloud frame are signaled based on the implicit geometry partition being determined to be enabled for the sequence of coded point cloud frames, the syntax elements including:

a syntax element indicating a first dimension size of the bounding box,

a syntax element indicating a difference between a second dimension size of the bounding box and the first dimension size of the bounding box, and

a syntax element indicating a difference between a third dimension size of the bounding box and the second dimension size of the bounding box.

4. The method of claim 1 , further comprising:

determining a syntax element indicating a 3D size of three dimensions of the bounding box of the slice of the coded point cloud frame is signaled based on the implicit geometry partition being determined to be disabled for the sequence of coded point cloud frames, the three dimensions of the bounding box having the same 3D size.

5. The method of claim 1 , wherein the reconstructing the octree includes:

determining a planar mode is not available for the current node at one of x, y, and z directions where no partition is performed for the current node by the implicit geometry partition.

6. The method of claim 1 , wherein the reconstructing the octree includes:

determining a planar mode is not available for the current node when three dimensions of the current node are not equal.

7. The method of claim 1 , wherein the reconstructing the octree includes:

performing a geometry octree occupancy parsing process, where for a bin having an index of binIdx in an occupancy code, a variable binIsInferred is set according to the following:

binIsInferred is set equal to 1 based on

(1) a variable NeighbourPattern is equal to 0 and a number of previously decoded 1-valued bins is less than or equal to (binIdx+minOccupied−maxOccupied), or

(2) the variable NeighbourPattern is not equal to 0, binIdx is equal to maxOccupied−1 and values of all previous decoded bins are zero,

where minOccupied=2, and maxOccupied=8 when an OT partition is applied, maxOccupied=4 when the QT partition is applied, maxOccupied=2 when the BT partition is applied, and

otherwise, binIsInferred is set equal to 0.

8. An apparatus of point cloud processing, comprising circuitry configured to:

receive a first syntax element in a bitstream corresponding to a sequence of coded point cloud frames, the first syntax element indicating whether implicit geometry partition is enabled for the sequence of coded point cloud frames;

determine the implicit geometry partition is enabled for the sequence of coded point cloud frames based on the first syntax element; and

reconstruct an octree representing a geometry of points in a bounding box of a slice in a coded point cloud frame in the sequence of coded point cloud frames based on the implicit geometry partition being determined to be enabled for the sequence of coded point cloud frames, a partition type being selected from a quadtree (QT) partition type in a three-dimensional (3D) space, a binary tree (BT) partition type in the 3D space, and an octree (OT) partition type in the 3D space for partitioning a current node of the octree in the implicit geometry partition.

9. The apparatus of claim 8 , wherein the circuitry is further configured to:

determine two parameters are signaled based on the implicit geometry partition being determined to be enabled for the sequence of coded point cloud frames, the two parameters including:

a maximal number of QT and BT partitions performed before OT partitions, and

a minimal size of QT and BT partitions that prevents QT and BT partitions of a node when all dimensions of the node are smaller than or equal to the minimal size.

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

determine syntax elements indicating 3D sizes of the bounding box of the slice of the coded point cloud frame are signaled based on the implicit geometry partition being determined to be enabled for the sequence of coded point cloud frames, the syntax elements including:

a syntax element indicating a first dimension size of the bounding box,

a syntax element indicating a difference between a second dimension size of the bounding box and the first dimension size of the bounding box, and

a syntax element indicating a difference between a third dimension size of the bounding box and the second dimension size of the bounding box.

11. The apparatus of claim 8 , wherein the circuitry is further configured to:

determine a syntax element indicating a 3D size of three dimensions of the bounding box of the slice of the coded point cloud frame is signaled based on the implicit geometry partition being determined to be disabled for the sequence of coded point cloud frames, the three dimensions of the bounding box having the same 3D size.

12. The apparatus of claim 8 , wherein the circuitry is further configured to:

determine a planar mode is not available for the current node at one of x, y, and z directions where no partition is performed for the current node by the implicit geometry partition.

13. The apparatus of claim 8 , wherein the circuitry is further configured to:

determine a planar mode is not available for the current node when three dimensions of the current node are not equal.

14. The apparatus of claim 8 , wherein the circuitry is further configured to:

perform a geometry octree occupancy parsing process, where for a bin having an index of binIdx in an occupancy code, a variable binIsInferred is set according to the following:

binIsInferred is set equal to 1 based on

(1) a variable NeighbourPattern is equal to 0 and a number of previously decoded 1-valued bins is less than or equal to (binIdx+minOccupied−maxOccupied), or

(2) the variable NeighbourPattern is not equal to 0, binIdx is equal to maxOccupied−1 and values of all previous decoded bins are zero,

where minOccupied=2, and maxOccupied=8 when an OT partition is applied, maxOccupied=4 when the QT partition is applied, maxOccupied=2 when the BT partition is applied, and

otherwise, binIsInferred is set equal to 0.

15. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform a method of point cloud processing, the method comprising:

receiving a first syntax element in a bitstream corresponding to a sequence of coded point cloud frames, the first syntax element indicating whether implicit geometry partition is enabled for the sequence of coded point cloud frames;

determining the implicit geometry partition is enabled for the sequence of coded point cloud frames based on the first syntax element; and

reconstructing an octree representing a geometry of points in a bounding box of a slice in a coded point cloud frame in the sequence of coded point cloud frames based on the implicit geometry partition being determined to be enabled for the sequence of coded point cloud frames, a partition type being selected from a quadtree (QT) partition type in a three-dimensional (3D) space, a binary tree (BT) partition type in the 3D space, and an octree (OT) partition type in the 3D space for partitioning a current node of the octree in the implicit geometry partition.

16. The non-transitory computer-readable medium of claim 15 , wherein the method further comprising:

determining two parameters are signaled based on the implicit geometry partition being determined to be enabled for the sequence of coded point cloud frames, the two parameters including:

a maximal number of QT and BT partitions performed before OT partitions, and

a minimal size of QT and BT partitions that prevents QT and BT partitions of a node when all dimensions of the node are smaller than or equal to the minimal size.

17. The non-transitory computer-readable medium of claim 15 , wherein the method further comprising:

determining syntax elements indicating 3D sizes of the bounding box of the slice of the coded point cloud frame are signaled based on the implicit geometry partition being determined to be enabled for the sequence of coded point cloud frames, the syntax elements including:

a syntax element indicating a first dimension size of the bounding box,

a syntax element indicating a difference between a second dimension size of the bounding box and the first dimension size of the bounding box, and

a syntax element indicating a difference between a third dimension size of the bounding box and the second dimension size of the bounding box.

18. The non-transitory computer-readable medium of claim 15 , wherein the method further comprising:

determining a syntax element indicating a 3D size of three dimensions of the bounding box of the slice of the coded point cloud frame is signaled based on the implicit geometry partition being determined to be disabled for the sequence of coded point cloud frames, the three dimensions of the bounding box having the same 3D size.

19. The non-transitory computer-readable medium of claim 15 wherein the reconstructing the octree includes:

determining a planar mode is not available for the current node at one of x, y, and z directions where no partition is performed for the current node by the implicit geometry partition.

20. The non-transitory computer-readable medium of claim 15 , wherein the reconstructing the octree includes:

determining a planar mode is not available for the current node when three dimensions of the current node are not equal.