Point cloud data transmission device, point cloud data transmission method, point cloud data reception device, and point cloud data reception method

1. A method of transmitting point cloud data, the method comprising:

acquiring point cloud data that comprises points;

encoding geometry information included in the point cloud data;

encoding attribute information included in the point cloud data; and

transmitting the encoded geometry information and the encoded attribute information,

wherein the encoding of the geometry information comprises:

generating an octree structure by recursively subdividing a bounding box for the point cloud data, wherein the octree structure is formed of levels, wherein each of the levels except a leaf node level includes a plurality of nodes and wherein each of the plurality of nodes is an occupied node that includes one or more points or a unoccupied node that does not include any point, and

entropy encoding the geometry information based on the octree structure, wherein the encoding of the attribute information comprises:

selecting predicted attribute information of a node to be attribute-encoded based on the octree structure, wherein attribute information of at least one of nodes in the octree structure is used for the predicted attribute information, and wherein, based on a parent node of the node to be attribute-encoded including two or more occupied child nodes that include the node, one of the two or more occupied child nodes is selected for the predicted attribute information, and

acquiring residual attribute information based on the attribute information of the node to be attribute-encoded and the predicted attribute information.

2. The method of claim 1 , wherein the encoding of the geometry information entropy-encodes occupancy codes assigned to occupied nodes in the octree structure, thereby outputting a geometry bitstream.

3. The method of claim 1 , wherein the encoding of the attribute information further comprises:

quantizing the residual attribute information based on a quantization coefficient; and

transmitting an attribute bitstream by entropy-encoding the quantized residual attribute information.

4. The method of claim 3 ,

wherein the attribute bitstream further includes signaling information, and

wherein the signaling information includes information for encoding of the attribute information.

5. The method of claim 1 ,

wherein the levels include a root node level and the leaf node level,

wherein the leaf node level corresponds to a lowest layer of the octree structure, and

wherein the root node level corresponds to a highest layer of the octree structure.

6. An apparatus configured to transmit point cloud data, the apparatus comprising:

an acquirer configured to acquire point cloud data that comprises points;

a geometry encoder configured to encode geometry information included in the point cloud data;

an attribute encoder configured to encode attribute information included in the point cloud data; and

a transmitter configured to transmit the encoded geometry information and the encoded attribute information,

wherein the geometry encoder is configured to generate an octree structure by recursively subdividing a bounding box for the point cloud data and entropy-encode the geometry information based on the octree structure, wherein the octree structure is formed of levels, wherein each of the levels except a leaf node level includes a plurality of nodes, and wherein each of the plurality of nodes is an occupied node that includes one or more points or a unoccupied node that does not include any point, and

wherein the attribute encoder is configured to:

select predicted attribute information of a node to be attribute-encoded based on the octree structure, wherein attribute information of at least one of nodes in the octree structure is used for the predicted attribute information, and wherein, based on a parent node of the node to be attribute-encoded including two or more occupied child nodes that include the node, one of the two or more occupied child nodes is selected for the predicted attribute information, and

acquire residual attribute information based on the attribute information of the node to be attribute-encoded and the predicted attribute information.

7. The apparatus of claim 6 , wherein the geometry encoder is configured to entropy-encode occupancy codes assigned to occupied nodes in the octree structure.

8. The apparatus of claim 7 , wherein the attribute encoder further comprises:

a quantizer configured to quantize the residual attribute information based on a quantization coefficient; and

an arithmetic encoder configured to transmit an attribute bitstream by entropy-encoding the quantized residual attribute information.

9. The apparatus of claim 8 , wherein the attribute bitstream further includes signaling information,

wherein the signaling information includes information for encoding of the attribute information.

10. The apparatus of claim 7 ,

wherein the levels include a root node level and the leaf node level,

wherein the leaf node level corresponds to a lowest layer of the octree structure, and

wherein the root node corresponds to a highest layer of the octree structure.

11. A method of receiving point cloud data, the method comprising:

receiving point cloud data and signaling information;

decoding geometry information included in the point cloud data;

decoding attribute information included in the point cloud data; and

processing and rendering the decoded geometry information and the decoded attribute information,

wherein decoding the geometry information comprises:

entropy decoding occupancy codes in the geometry information,

generating an octree structure based on the occupancy codes, wherein the octree structure is formed of levels, wherein each of the levels except a leaf node level includes a plurality of nodes, and wherein each of the plurality of nodes is an occupied node that includes one or more points or an unoccupied node that does not include any point, and

wherein decoding the attribute information comprises:

selecting predicted attribute information of a node to be attribute-decoded based on the octree structure, wherein attribute information of at least one of nodes in the octree structure is used for the predicted attribute information, and wherein, based on a parent node of the node to be attribute-encoded including two or more occupied child nodes that include the node, one of the two or more occupied child nodes is selected for the predicted attribute information, and

restoring the attribute information of the node to be attribute-decoded based on the predicted attribute information and residual attribute information in the received attribute information.

12. The method of claim 11 , wherein the signaling information includes information for decoding of the attribute information.

13. The method of claim 11 ,

wherein the levels include a root node level and the leaf node level,

wherein the leaf node level corresponds to a lowest layer of the octree structure, and

wherein the root node corresponds to a highest layer of the octree structure.

14. An apparatus configured to receive point cloud data, the apparatus comprising:

a receiver configured to receive point cloud data and signaling information;

a geometry decoder configured to decode geometry information included in the point cloud data;

an attribute decoder configured to decode attribute information included in the point cloud data; and

a renderer configured to process and render the decoded geometry information and the decoded attribute information,

wherein the geometry information decoder is configured to entropy decode occupancy codes in the geometry information and generate an octree structure based on the occupancy codes, wherein the octree structure is formed of levels, wherein each of the levels except a leaf node level includes a plurality of nodes, and wherein each of the plurality of nodes is an occupied node that includes one or more points or a unoccupied node that does not include any point, and

wherein the attribute information decoder is configured to:

select predicted attribute information of a node to be attribute-decoded based on the octree structure, wherein attribute information of at least one of nodes in the octree structure is used for the predicted attribute information, and wherein, based on a parent node of the node to be attribute-encoded including two or more occupied child nodes that include the node, one of the two or more occupied child nodes is selected for the predicted attribute information, and

restore the attribute information of the node to be attribute-decoded based on the predicted attribute information and residual attribute information in the received attribute information.

15. The apparatus of claim 14 , wherein the signaling information includes information for decoding of the attribute information.