Three-dimensional data encoding method, three-dimensional data decoding method, three-dimensional data encoding device, and three-dimensional data decoding device

1. A three-dimensional data encoding method, comprising:

generating predicted position information using position information on three-dimensional points included in three-dimensional reference data associated with a time different from a time associated with current three-dimensional data; and

encoding position information on three-dimensional points included in the current three-dimensional data, using the predicted position information,

wherein in the generating of the predicted position information, the predicted position information is generated by applying (i) a first process including rotation and translation to the position information on the three-dimensional points included in the three-dimensional reference data, and (ii) a second process including at least one of rotation and translation to the position information on the three-dimensional points obtained through the first process, the first process using a first unit and the second process using a second unit that is smaller than the first unit, and

the first unit is a space having a cube structure, and the second unit is a volume from among a plurality of volumes obtained by subdividing the space and having a cube structure.

2. The three-dimensional data encoding method according to claim 1 , further comprising:

encoding information that indicates contents of the at least one of the first process and the second process.

3. The three-dimensional data encoding method according to claim 1 , wherein in the encoding:

differential position information is calculated, the differential position information being a difference between the predicted position information and the position information on the three-dimensional points included in the current three-dimensional data; and

the differential position information is encoded.

4. The three-dimensional data encoding method according to claim 1 , wherein the position information is:

represented using an octree structure; and

expressed in a scan order that prioritizes a breadth over a depth in the octree structure.

5. The three-dimensional data encoding method according to claim 1 , wherein the position information is:

represented using an octree structure; and

expressed in a scan order that prioritizes a depth over a breadth in the octree structure.

6. The three-dimensional data encoding method according to claim 1 , wherein

each of the three-dimensional points included in the three-dimensional reference data and the current three-dimensional data includes attribute information, and

the three-dimensional data encoding method further comprises:

generating predicted attribute information using the attribute information of the three-dimensional points included in the three-dimensional reference data; and

encoding the attribute information of the three-dimensional points included in the current three-dimensional data, using the predicted attribute information.

7. A three-dimensional data decoding method, comprising:

generating predicted position information using position information on three-dimensional points included in three-dimensional reference data associated with a time different from a time associated with current three-dimensional data; and

restoring position information on three-dimensional points included in the current three-dimensional data, by decoding encoded position information included in an encoded signal, using the predicted position information,

wherein in the generating of the predicted position information, the predicted position information is generated by applying (i) a first process including rotation and translation to the position information on the three-dimensional points included in the three-dimensional reference data, and (ii) a second process including at least one of rotation and translation to the position information on the three-dimensional points obtained through the first process, the first process using a first unit and the second process using a second unit that is smaller than the first unit, and

the first unit is a space having a cube structure, and the second unit is a volume from among a plurality of volumes obtained by subdividing the space and having a cube structure.

8. The three-dimensional data decoding method according to claim 7 , further comprising:

decoding information that indicates contents of the at least one of the first process and the second process.

9. The three-dimensional data decoding method according to claim 7 , wherein

the encoded position information is differential position information, the differential position information being a difference between the predicted position information and the position information on the three-dimensional points included in the current three-dimensional data; and

in the restoring, the position information on the three-dimensional points included in the current three-dimensional data is restored by adding the differential position information to the predicted position information.

10. The three-dimensional data decoding method according to claim 7 , wherein the position information is:

represented using an octree structure; and

expressed in a scan order that prioritizes a breadth over a depth in the octree structure.

11. The three-dimensional data decoding method according to claim 7 , wherein the position information is:

represented using an octree structure; and

expressed in a scan order that prioritizes a depth over a breadth in the octree structure.

12. The three-dimensional data decoding method according to claim 7 , wherein

each of the three-dimensional points included in the three-dimensional reference data and the current three-dimensional data includes attribute information, and

the three-dimensional data decoding method further comprises:

generating predicted attribute information using the attribute information of the three-dimensional points included in the three-dimensional reference data; and

restoring the attribute information of the three-dimensional points included in the current three-dimensional data, by decoding encoded attribute information included in the encoded signal, using the predicted position information.

13. A three-dimensional data encoding device, comprising:

a processor; and

memory, wherein

the processor uses the memory to:

generate predicted position information using position information on three-dimensional points included in three-dimensional reference data associated with a time different from a time associated with current three-dimensional data; and

encode position information on three-dimensional points included in the current three-dimensional data, using the predicted position information, and

the processor generates the predicted position information by applying (i) a first process including rotation and translation to the position information on the three-dimensional points included in the three-dimensional reference data, and (ii) a second process including at least one of rotation and translation to the position information on the three-dimensional points obtained through the first process, the first process using a first unit and the second process using a second unit that is smaller than the first unit, and

the first unit is a space having a cube structure, and the second unit is a volume from among a plurality of volumes obtained by subdividing the space and having a cube structure.

14. A three-dimensional data decoding device, comprising:

a processor; and

memory, wherein

the processor uses the memory to:

generate predicted position information using position information on three-dimensional points included in three-dimensional reference data associated with a time different from a time associated with current three-dimensional data; and

restore position information on three-dimensional points included in the current three-dimensional data, by decoding encoded position information included in an encoded signal, using the predicted position information, and

the processor generates the predicted position information by applying (i) a first process including rotation and translation to the position information on the three-dimensional points included in the three-dimensional reference data, and (ii) a second process including at least one of rotation and translation to the position information on the three-dimensional points obtained through the first process, the first process using a first unit and the second process using a second unit that is smaller than the first unit, and

the first unit is a space having a cube structure, and the second unit is a volume from among a plurality of volumes obtained by subdividing the space and having a cube structure.