Attribute residual coding in G-PCC

A method of decoding a point cloud, the method comprising:

• decoding values for a plurality of components of one attribute of one point in the point cloud, the values indicative of residual values for the plurality of components;
• in a condition where residual values for all components of the plurality of components of the one attribute except one component of the plurality of components of the one attribute are equal to zero, adding an offset to a decoded value for the one component of the one attribute to determine a magnitude of a residual value for the one component;
• and
• reconstructing the components of the one attribute of the one point based on the residual values for the components, wherein reconstructing the components comprises adding a respective residual value, of the residual values, for a respective component of the plurality of components to a respective predictor for the respective component.

A device for encoding a point cloud, the device comprising:

• one or more memories configured to store the point cloud;
• and
• processing circuitry configured to:
• determine respective residual values for each component of a plurality of components of one attribute of one point in the point cloud, wherein each respective residual value is based on a difference between a respective value of each component and a respective predictor for each component;
• in a condition where the residual values for all components of the plurality of components of the one attribute of the one point in the point cloud except one component of the plurality of components of the one attribute are equal to zero, determine a value for the one component that is equal to a magnitude of a residual value of the one component of the one attribute minus an offset;
• encode the value of the one component;
• and
• signal the encoded value in a bitstream.

A device for decoding a point cloud, the device comprising:

• one or more memories configured to store the point cloud;
• and
• processing circuitry configured to:
• decode values for a plurality of components of one attribute of one point in the point cloud, the values indicative of residual values for the plurality of components;
• in a condition where residual values for all components of the plurality of components except one component of the plurality of components of the one attribute are equal to zero, add an offset to a decoded value for the one component of the one attribute to determine a magnitude of a residual value for the one component;
• and
• reconstruct the components of the one attribute of the one point based on the residual values for the components, wherein to reconstruct the components, the processing circuitry is configured to add a respective residual value, of the residual values, for a respective component of the plurality of components to a respective predictor for the respective component.

A computer-readable storage medium storing instructions thereon that when executed cause one or more processors of a device for encoding a point cloud to:

• determine respective residual values for each component of a plurality of components of one attribute of one point in the point cloud, wherein each respective residual value is based on a difference between a respective value of each component and a respective predictor for each component;
• in a condition where the residual values for all components of the plurality of components of the one attribute of the one point in the point cloud except one component of the plurality of components of the one attribute are equal to zero, determine a value for the one component that is equal to a magnitude of a residual value of the one component of the one attribute minus an offset;
• encode the value of the one component;
• and
• signal the encoded value in a bitstream.

A computer-readable storage medium storing instructions thereon that when executed cause one or more processors of a device for decoding a point cloud to:

• decode values for a plurality of components of one attribute of one point in the point cloud, the values indicative of residual values for the plurality of components;
• in a condition where residual values for all components of the plurality of components of the one attribute except one component of the plurality of components of the one attribute are equal to zero, add an offset to a decoded value for the one component of the one attribute to determine a magnitude of a residual value for the one component;
• and
• reconstruct the components of the one attribute of the one point based on the residual values for the components, wherein the instructions that cause the one or more processors to reconstruct the components comprise instructions that cause the one or more processors to add a respective residual value, of the residual values, for a respective component of the plurality of components to a respective predictor for the respective component.