Method and apparatus for vertex error correction

A method for decoding a bitstream representing a 3D model, comprising:

• accessing a reconstructed instance corresponding to an instance;
• determining a quantization index from the bitstream;
• determining a quantization parameter in response to the quantization index;
• decoding a vertex coordinate error representative of an error between a vertex of the instance and a corresponding vertex of the reconstructed instance, based on the determined quantization parameter;
• and
• refining the reconstructed instance in response to the decoded vertex coordinate error.

An apparatus for generating a bitstream representing a 3D model, comprising at least one memory and one or more processors, the one or more processors configured to:

• access a reconstructed instance corresponding to an instance;
• determine a quantization parameter based on a vertex coordinate error between a vertex of the instance and a corresponding vertex of the reconstructed instance;
• determine a quantization index in response to the determined quantization parameter;
• and
• encode the quantization index and the vertex coordinate error into the bitstream.

An apparatus for decoding a bitstream representing a 3D model, comprising at least a memory and one or more processors, the one or more processors configured to:

• access a reconstructed instance corresponding to an instance;
• determine a quantization index from the bitstream;
• determine a quantization parameter corresponding to the quantization index;
• decode a vertex coordinate error representative of an error between a vertex of the instance and a corresponding vertex of the reconstructed instance, based on the determined quantization parameter;
• and
• refine the reconstructed instance in response to the decoded vertex coordinate error.