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:

obtaining three-dimensional point data that includes an attribute information item of each of three-dimensional points;

encoding the attribute information item; and

generating a bitstream including the attribute information item encoded and a transform identification information item indicating whether a transform process is performed on the attribute information item,

wherein when the transform identification information item indicates that the transform process is performed on the attribute information item, a transform parameter is included in the bitstream, the transform parameter being used in the transform process performed on the attribute information item, the transform process including at least one of a scaling process or an offset process performed on a numerical value included in the attribute information item, and

wherein when the transform identification information item does not indicate that the transform process is performed on the attribute information item, the transform parameter is not included in the bitstream.

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

wherein a plurality of attribute information items each of which is the attribute information item are obtained in the obtaining,

in the generating, whether the transform parameter is included in the bitstream is determined for each of the plurality of attribute information items.

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

wherein when the transform process is performed on the attribute information item, (i) the encoding of the attribute information includes executing the transform process including performing both the scaling process and the offset process, and (ii) the generating of the bitstream comprises generating an order information item and including the order information in the bitstream, the order information item indicating an order in which the scaling process and the offset process have been performed.

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

wherein when transform identification information item indicates that the transform process is performed on the attribute information item, the transform parameter is stored in an additional information item common to sequences in the generating.

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

wherein in the scaling process, at least one of a multiplication and division operation or a shift operation is performed on the numerical value indicated by the attribute information item, and

in the offset process, an addition and subtraction operation is performed on the numerical value indicated by the attribute information item.

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

wherein when the transform process is performed on the attribute information item, in the encoding of the attribute information item, the numerical value indicated by the attribute information item is transformed into a positive value by the transform process including at least one of the scaling process or the offset process performed on the numerical value included in the attribute information item, and the positive value is encoded.

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

wherein when the numerical value indicated by the attribute information item is unable to be processed in the encoding of the attribute information item, the encoding of the attribute information item includes transforming the numerical value indicated by the attribute information item into a positive value by executing the transform process including at least one of the scaling process or the offset process performed on the numerical value included in the attribute information item, and encoding the positive value.

8 . A three-dimensional data decoding method comprising:

obtaining a bitstream including three-dimensional point data that includes an encoded attribute information item of each of three-dimensional points and a transform identification information item indicating whether a transform process is performed on the attribute information item,

wherein when the transform identification information item indicates that the transform process is performed on the attribute information item, a transform parameter is included in the bitstream, the transform parameter being used in the transform process performed on the attribute information item, the transform process including at least one of a scaling process or an offset process performed on a numerical value included in the attribute information item,

wherein when the transform identification information item does not indicate that the transform process is performed on the attribute information item, the transform parameter is not included in the bitstream, and

wherein the three-dimensional data decoding method further comprises:

switching whether the transform parameter is obtained from the bitstream, based on the transform identification information; and

decoding the attribute information item based on the transform identification information.

9 . The three-dimensional data decoding method according to claim 8 ,

wherein the bitstream includes a plurality of encoded attribute information items each of which is the encoded attribute information item,

each of the plurality of encoded attribute information items is decoded in the decoding of the attribute information item, and

the switching whether the transform parameter is obtained from the bitstream is performed for each of the plurality of encoded attribute information items based on the transform identification information.

10 . The three-dimensional data decoding method according to claim 8 ,

wherein when the transform process is performed on the attribute information item, (i) the bitstream further includes an order information item indicating that both the scaling process and the offset process have been performed and an order in which the scaling process and the offset process have been performed, and (ii) in the decoding of the attribute information item, the scaling process and the offset process are performed in the order based on the order information item.

11 . The three-dimensional data decoding method according to claim 8 ,

wherein when transform identification information item indicates that the transform process is performed on the attribute information item, in the bitstream, the transform parameter is stored in an additional information item common to sequences.

12 . The three-dimensional data decoding method according to claim 8 ,

wherein in the scaling process, at least one of a multiplication and division operation or a shift operation is performed on the numerical value indicated by the attribute information item, and

in the offset process, an addition and subtraction operation is performed on the numerical value indicated by the attribute information item.

13 . The three-dimensional data decoding method according to claim 8 ,

wherein when the transform process is performed on the attribute information item, the numerical value indicated by the attribute information item is transformed into a positive value by the transform process including at least one of the scaling process or the offset process performed on the numerical value included in the attribute information item, and in the decoding of the attribute information item, the positive value is decoded.

14 . A three-dimensional data encoding device comprising:

a processor; and

memory,

wherein using the memory, the processor:

obtains three-dimensional point data that includes an attribute information item of each of three-dimensional points;

encodes the attribute information item; and

generates a bitstream including the attribute information item encoded and a transform identification information item indicating whether a transform process is performed on the attribute information,

wherein when the transform identification information item indicates that the transform process is performed on the attribute information item, a transform parameter is included in the bitstream, the transform parameter being used in the transform process performed on the attribute information item, the transform process including at least one of a scaling process or an offset process performed on a numerical value included in the attribute information item, and

wherein when the transform identification information item does not indicate that the transform process is performed on the attribute information item, the transform parameter is not included in the bitstream.

15 . A three-dimensional data decoding device comprising:

a processor; and

memory,

wherein using the memory, the processor:

obtains a bitstream including three-dimensional point data that includes an encoded attribute information item of each of three-dimensional points and a transform identification information item indicating whether transform process is performed on the attribute information item,

wherein when the transform identification information item indicates that the transform process is performed on the attribute information item, a transform parameter is included in the bitstream, the transform parameter being used in the transform process performed on the attribute information item, the transform process including at least one of a scaling process or an offset process performed on a numerical value included in the attribute information item,

wherein when the transform identification information item does not indicate that the transform process is performed on the attribute information item, the transform parameter is not included in the bitstream, and

wherein the processor further:

switches whether the transform parameter is obtained from the bitstream, based on the transform identification information; and

decodes the attribute information item based on the transform identification information.