Method and apparatus of encoding/decoding point cloud geometry data sensed by at least one sensor

A method of decoding, from a bitstream, point cloud geometry data sensed by at least one sensor associated with a sensor index, the point cloud geometry data being represented by ordered coarse points occupying some discrete positions of a set of discrete positions of a two-dimensional space, each occupied coarse point being located within the two-dimensional space by a sensor index associated with a sensor that sensed a point of the point cloud associated with the occupied coarse point, and a sample index associated with a sensing time instant at which the point of the point cloud has been sensed, each occupied coarse point being associated with a radius based on a distance of the point of the point cloud from a referential, wherein the method comprises:

• obtaining a list of candidate radiuses (L={r2}) for a first occupied coarse point (P1) having a first sensor index (λ1) and a first sample index (s1) and being associated with a first radius (r1), the list of candidate radiuses comprising at least one second radius (r2) associated with at least one second occupied coarse point (P2) having a second sensor index (λ2) different of the first sensor index (λ1) and having a second sample index (s2) lower than the first sample index (s1), the at least one second occupied coarse point (P2) further fulfilling at least one eligibility condition indicating that a radius associated with the at least one second occupied coarse point (P2) is promising for reducing a dynamic of a predictive residual radius (rres) when the first radius (r1) is predictively encoded;
• decoding, from the bitstream, for a first occupied coarse point (P1), a data (Ipred) representative of a selected predicting radius (rpred) in the list of candidate radiuses (L={r2});
• decoding, from the bitstream, for the first occupied coarse point, a residual radius (rres);
• and
• obtaining a radius (r1) associated with a point of the point represented by the first occupied coarse point (P1), based on the residual radius (rres) and the selected predicting radius (rpred) is obtained from the data (Ipred) and the list of candidate radiuses (L={r2}).

An apparatus of encoding, into a bitstream, point cloud geometry data sensed by at least one sensor associated with a sensor index, the point cloud geometry data being represented by ordered coarse points occupying some discrete positions of a set of discrete positions of a two-dimensional space, each occupied coarse point is located within the two-dimensional space by a sensor index associated with a sensor that sensed a point of the point cloud associated with the occupied coarse point, and a sample index associated with a sensing time instant at which the point of the point cloud has been sensed, each occupied coarse point is associated with a radius based on a distance of the point of the point cloud from a referential, wherein the apparatus comprises at least one processor configured to:

• obtain a list of candidate radiuses (L={r2}) for a first occupied coarse point (P1) having a first sensor index (λ1), a first sample index (s1) and being associated with a first radius (r1), the list of candidate radiuses comprises at least one second radius (r2) associated with at least one second occupied coarse point (P2) having a second sensor index (λ2) different from the first sensor index (λ1) and having a second sample index (s2) lower than or equal to the first sample index (s1), the at least one second occupied coarse point (P2) further fulfilling at least one eligibility condition indicating that the radius associated with the at least one second occupied coarse point (P2) is likely reducing a dynamic of a predictive residual radius (rres) when the first radius (r1) is predictively encoded;
• select, for the first occupied coarse point (P1), a selected predicting radius (rpred) from the list of candidate radiuses (L={r2});
• encode, in the bitstream, a data (Ipred) representative of the selected predicting radius (rpred) in the list of candidate radiuses (L={r2});
• and
• predictively encode, in the bitstream, a residual radius (rres) between the first radius (r1) and the selected predicting radius (rpred).