Processing a point cloud

1. A method comprising:

adding at least one 3D sample to a point cloud frame, said at least one 3D sample being added according to a difference between a depth value of at least one neighboring 3D sample of a current 3D sample of the point cloud frame and a depth value of said current 3D sample, wherein the difference between the depth value of the neighboring 3D sample and the depth value of said current 3D sample is a first depth difference determined as a maximum depth difference between depth values of neighboring 3D samples of the current 3D sample and the depth value of the current 3D sample, and wherein at least one 3D sample is added with a depth value belonging to a range from the depth value of the current 3D sample of said point cloud frame and a depth value being equal to the sum of the depth value of said current 3D sample and the first depth difference minus 1.

2. The method of claim 1 , wherein said point cloud frame is obtained by de-projecting at least one geometry image representing the geometry of a point cloud frame.

3. The method of claim 1 , wherein at least one 3D sample is added, at the same 2D location as a 2D sample representing the projection of said current 3D sample of said point cloud frame onto an image plane, up to the first depth difference.

4. The method of claim 3 , wherein responsive to a determination that the first depth difference equals 0 or 1, a 3D sample is added at said 2D location.

5. The method of claim 1 , wherein at least one 3D sample is added, at the same 2D location as a 2D sample representing the projection of said current 3D sample of said point cloud frame onto an image plane, up to the first depth difference minus 1, and another 3D sample is added at the 2D location as a 2D sample representing the projection of the neighboring 3D sample having a depth value equals to the first depth difference minus 1.

6. The method of claim 1 , wherein said first depth difference is equal to or higher than a first value.

7. The method of claim 6 , wherein said first value is greater or equal to 1 or 2.

8. The method of claim 6 , wherein said first value is transmitted in a bitstream.

9. The method of claim 6 , wherein the method further comprises decoding a bitstream to provide said first value.

10. The method of claim 1 , wherein when determining the maximum depth difference between depth values of neighboring 3D samples of the current 3D sample and the depth value of the current 3D sample, a difference between the depth value of the current 3D sample of the point cloud frame and the depth value of a neighboring 3D sample is ignored if said difference does not belong to a first range of values.

11. The method of claim 1 comprising:

assigning a color-coding mode to at least one added 3D sample, said color-coding mode indicating that color information associated with said at least one added 3D sample is encoded in a bitstream; and

encoding in a bitstream the color information associated with said at least one 3D sample.

12. The method of claim 11 , wherein said color-coding mode is assigned to said 3D sample according to said first depth difference associated with said 3D sample.

13. A non-transitory computer-readable medium including instructions which, when executed by a computer, cause the computer to carry out the method of claim 1 .

14. A device comprising at least one processor configured to:

add at least one 3D sample to a point cloud frame, said at least one 3D sample being added according to a difference between a depth value of at least one neighboring 3D sample of a current 3D sample and the depth value of said current 3D sample, wherein the difference between the depth value of the neighboring 3D sample and the depth value of said current 3D sample is a first depth difference determined as a maximum depth difference between depth values of neighboring 3D samples of the current 3D sample and the depth value of the current 3D sample, and wherein at least one 3D sample is added with a depth value belonging to a range from the depth value of the current 3D sample of said point cloud frame and a depth value being equal to the sum of the depth value of said current 3D sample and the first depth difference minus 1.

15. The device of claim 14 , wherein at least one 3D sample is added, at the same 2D location as a 2D sample representing the projection of said current 3D sample of said point cloud frame onto an image plane, up to the first depth difference.

16. The device of claim 14 , wherein said first depth difference is equal to or higher than a first value.

17. The device of claim 16 , wherein the at least one processor is further configured to decode a bitstream to provide said first value.

18. The device of claim 14 , wherein when determining the maximum depth difference between depth values of neighboring 3D samples of the current 3D sample and the depth value of the current 3D sample, a difference between the depth value of the current 3D sample of the point cloud frame and the depth value of a neighboring 3D sample is ignored if said difference does not belong to a first range of values.

19. The device of claim 14 , wherein the at least one processor is further configured to:

assign a color-coding mode to at least one added 3D sample, said color-coding mode indicating that color information associated with said at least one added 3D sample is encoded in a bitstream; and

encode in a bitstream the color information associated with said at least one 3D sample.