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 a plurality of three-dimensional points;

generating a tree structure using the plurality of three-dimensional points;

encoding geometry information of the plurality of three-dimensional points using the tree structure; and

generating a bitstream including encoded data obtained from the encoding, a total number of three-dimensional points included in the tree structure, and identification information indicating whether or not to rearrange the plurality of three-dimensional points in Morton order.

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

encoding attribute information of the plurality of three-dimensional points using the total number of the three-dimensional points.

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

in the encoding of the attribute information, the attribute information of the plurality of three-dimensional points is encoded after the plurality of three-dimensional points are rearranged using the total number of the three-dimensional points, and

in the generating of a bitstream, the bitstream further including the attribute information encoded is generated.

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

the encoding of the attribute information includes:

generating a hierarchical structure composed of one or more layers, by layering the three-dimensional points; and

encoding the attribute information of each of the plurality of three-dimensional points using the hierarchical structure.

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

if the plurality of three-dimensional points that are not arranged in the Morton order are layered in the generating of the hierarchical structure, the identification information indicates that the plurality of three-dimensional points are not to be arranged in the Morton order.

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

if the plurality of three-dimensional points that are arranged in the Morton order are layered in the generating of the hierarchical structure, the identification information indicates that the plurality of three-dimensional points are to be arranged in the Morton order.

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

the hierarchical structure is composed of a single layer.

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

the hierarchical structure is generated by classifying each of the plurality of three-dimensional points into one of the one or more layers so that a distance between three-dimensional points belonging to a higher layer is greater than a distance between three-dimensional points belonging to a lower layer.

9 . A three-dimensional data decoding method comprising:

obtaining a bitstream including encoded data and a total number of three-dimensional points included in a tree structure; and

calculating geometry information of a plurality of three-dimensional points by decoding the encoded data using the tree structure obtained from the bitstream and the total number of the three-dimensional points.

10 . The three-dimensional data decoding method according to claim 9 , further comprising:

calculating attribute information of the plurality of three-dimensional points by decoding the encoded data, according to whether or not the bitstream includes identification information indicating whether or not to rearrange the plurality of three-dimensional points in Morton order.

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

in the decoding, when the bitstream includes the identification information:

(i) when the identification information indicates that the plurality of three-dimensional points are not to be arranged in the Morton order, a hierarchical structure composed of one or more layers is generated by layering the plurality of three-dimensional points based on the geometry information of the plurality of three-dimensional points, without rearranging the plurality of three-dimensional points in the Morton order; and

(ii) the attribute information which is encoded is decoded using the hierarchical structure generated.

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

inclusion of the attribute information in the bitstream indicates that a hierarchical structure composed of one layer is generated by layering during encoding.

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

the hierarchical structure is generated by classifying each of the plurality of three-dimensional points into one of the one or more layers so that a distance between three-dimensional points belonging to a higher layer is greater than a distance between three-dimensional points belonging to a lower layer.

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

in the decoding, when the bitstream includes the identification information:

(i) when the identification information indicates that the plurality of three-dimensional points are to be arranged in the Morton order, the plurality of three-dimensional points are rearranged in the Morton order based on the geometry information of the plurality of three-dimensional points;

(ii) a hierarchical structure composed of one or more layers is generated by layering the plurality of three-dimensional points rearranged; and

(iii) the attribute information which is encoded is decoded using the hierarchical structure generated.