Point cloud coding method

1 . A point cloud decoding method, applied to a decoder and comprising:

determining reconstructed attribute information of occupied neighbouring nodes of a current node and reconstructed attribute information of occupied same-level neighbouring child nodes of a child node of the current node;

determining an attribute prediction value of the child node of the current node according to the reconstructed attribute information of the occupied neighbouring nodes and the reconstructed attribute information of the occupied same-level neighbouring child nodes of the child node of the current node; and

determining a first transformed coefficient by performing region adaptive hierarchal transform (RAHT) on the attribute prediction value, and determining reconstructed attribute information of the child node of the current node according to the first transformed coefficient.

2 . The method of claim 1 , wherein

the occupied neighbouring nodes comprise: the current node and an occupied coplanar neighbouring node and an occupied collinear neighbouring node of the current node; and

the occupied same-level neighbouring child nodes of the child node of the current node comprise: an occupied coplanar neighbouring node and an occupied collinear neighbouring node of the child node of the current node.

3 . The method of claim 2 , further comprising:

determining weights corresponding to the occupied neighbouring nodes and the occupied same-level neighbouring child nodes of the child node of the current node; and

determining the attribute prediction value of the child node of the current node by weighting the reconstructed attribute information of the occupied neighbouring nodes and the reconstructed attribute information of the occupied same-level neighbouring child nodes of the child node of the current node according to the weights.

4 . The method of claim 2 , further comprising:

determining reference neighbouring nodes by filtering the occupied neighbouring nodes and the occupied same-level neighbouring child nodes of the child node of the current node; and

determining the attribute prediction value of the child node of the current node according to reconstructed attribute information of the reference neighbouring nodes.

5 . The method of claim 4 , further comprising:

determining weights corresponding to the reference neighbouring nodes; and

determining the attribute prediction value of the child node of the current node by weighting the reconstructed attribute information of the reference neighbouring nodes according to the weights.

6 . The method of claim 4 , further comprising:

determining a first preset threshold according to reconstructed attribute information of the current node; and

determining the reference neighbouring nodes by filtering the occupied neighbouring nodes and the occupied same-level neighbouring child nodes of the child node of the current node according to the first preset threshold.

7 . The method of claim 3 , wherein

the weights comprise: a first weight corresponding to the current node, a second weight corresponding to the occupied coplanar neighbouring node of the current node, a third weight corresponding to the occupied collinear neighbouring node of the current node, a fourth weight corresponding to the occupied coplanar neighbouring node of the child node of the current node, and a fifth weight corresponding to the occupied collinear neighbouring node of the child node of the current node.

8 . The method of claim 1 , further comprising:

decoding a bitstream to determine a coefficient residual value of the child node of the current node;

determining a coefficient residual of the child node of the current node by performing inverse quantization on the coefficient residual value;

determining a second transformed coefficient of the child node of the current node according to the first transformed coefficient and the coefficient residual; and

determining the reconstructed attribute information of the child node of the current node by performing inverse transform on the second transformed coefficient.

9 . The method of claim 1 , wherein

the occupied same-level neighbouring child nodes of the child node of the current node and the child node of the current node are same-level neighbouring nodes, and the same-level neighbouring nodes are nodes of a same size.

10 . A point cloud decoding method, applied to a decoder and comprising:

determining a number of occupied neighbours of a parent node of a current node and a number of occupied neighbours of the current node, if the current node is not a root node;

determining reconstructed attribute information of occupied neighbouring nodes of the current node and reconstructed attribute information of occupied same-level neighbouring child nodes of a child node of the current node, if the number of the occupied neighbours of the parent node is greater than or equal to a first threshold and the number of the occupied neighbours of the current node is greater than or equal to a second threshold;

determining an attribute prediction value of the child node of the current node according to the reconstructed attribute information of the occupied neighbouring nodes and the reconstructed attribute information of the occupied same-level neighbouring child nodes of the child node of the current node; and

determining a first transformed coefficient by performing region adaptive hierarchal transform (RAHT) on the attribute prediction value, and determining reconstructed attribute information of the child node of the current node according to the first transformed coefficient.

11 . The method of claim 10 , further comprising:

decoding a bitstream to determine a quantized coefficient of the current node, if the current node is the root node;

determining a transformed coefficient by performing inverse quantization on the quantized coefficient; and

determining reconstructed attribute information of the current node by performing inverse transform on the transformed coefficient.

12 . The method of claim 10 , further comprising:

decoding a bitstream to determine a quantized coefficient of the current node, if the number of the occupied neighbours of the parent node is less than the first threshold or the number of the occupied neighbours of the current node is less than the second threshold;

determining a transformed coefficient by performing inverse quantization on the quantized coefficient; and

determining reconstructed attribute information of the current node by performing inverse transform on the transformed coefficient.

13 . A point cloud encoding method, applied to an encoder and comprising:

determining reconstructed attribute information of occupied neighbouring nodes of a current node and reconstructed attribute information of occupied same-level neighbouring child nodes of a child node of the current node;

determining an attribute prediction value of the child node of the current node according to the reconstructed attribute information of the occupied neighbouring nodes and the reconstructed attribute information of the occupied same-level neighbouring child nodes of the child node of the current node;

determining a first transformed coefficient by performing region adaptive hierarchal transform (RAHT) on the attribute prediction value, and determining a coefficient residual value of the child node of the current node according to the first transformed coefficient; and

signalling the coefficient residual value into a bitstream.

14 . The method of claim 13 , wherein

the occupied neighbouring nodes comprise: the current node and an occupied coplanar neighbouring node and an occupied collinear neighbouring node of the current node; and

the occupied same-level neighbouring child nodes of the child node of the current node comprise: an occupied coplanar neighbouring node and an occupied collinear neighbouring node of the child node of the current node.

15 . The method of claim 14 , further comprising:

determining weights corresponding to the occupied neighbouring nodes and the occupied same-level neighbouring child nodes of the child node of the current node; and

determining the attribute prediction value of the child node of the current node by weighting the reconstructed attribute information of the occupied neighbouring nodes and the reconstructed attribute information of the occupied same-level neighbouring child nodes of the child node of the current node according to the weights.

16 . The method of claim 14 , further comprising:

determining reference neighbouring nodes by filtering the occupied neighbouring nodes and the occupied same-level neighbouring child nodes of the child node of the current node; and

determining the attribute prediction value of the child node of the current node according to reconstructed attribute information of the reference neighbouring nodes.

17 . The method of claim 16 , further comprising:

determining weights corresponding to the reference neighbouring nodes; and

determining the attribute prediction value of the child node of the current node by weighting the reconstructed attribute information of the reference neighbouring nodes according to the weights.

18 . The method of claim 16 , further comprising:

determining a first prediction threshold and a second prediction threshold according to reconstructed attribute information of the current node; and

determining the reference neighbouring nodes by filtering the occupied neighbouring nodes and the occupied same-level neighbouring child nodes of the child node of the current node according to the first prediction threshold and the second prediction threshold.

19 . The method of claim 15 , wherein

the weights comprise: a first weight corresponding to the current node, a second weight corresponding to the occupied coplanar neighbouring node of the current node, a third weight corresponding to the occupied collinear neighbouring node of the current node, a fourth weight corresponding to the occupied coplanar neighbouring node of the child node of the current node, and a fifth weight corresponding to the occupied collinear neighbouring node of the child node of the current node.

20 . The method of claim 13 , further comprising:

determining a second transformed coefficient by performing RAHT on original attribute information of the child node of the current node;

determining a coefficient residual between the first transformed coefficient and the second transformed coefficient; and

determining the coefficient residual value by quantizing the coefficient residual.