Dual Degree Mesh Coding Entropy Encoding
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Solution Overview
Problem
Existing mesh compression standards do not effectively handle dynamic meshes with time-varying connectivity information and attribute maps, which are essential for advanced 3D content applications like real-time communications and VR/AR.
Innovation Solution
The proposed method generates a bitstream with an encoded 3D polygon mesh using dual degree connectivity, where vertex and face degrees are encoded separately, and employs context-adaptive binary arithmetic coding (CABAC) to improve coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dual degree encoding is used to encode vertex and face degrees separately, then coding efficiency is improved, but the complexity of the encoding process increases
Solution Approach 1:
The patent segments the encoding process into two separate sequences: one for vertex degrees and another for face degrees. Each sequence is independently encoded using CABAC with context models, allowing the encoder to handle different degree distributions separately and improve overall coding efficiency while managing complexity through modular processing
Solution Approach 2:
The patent introduces degree offset parameters (k1 for vertices, k2 for faces) that are added to the original degree values before encoding. This parameter transformation reduces the dynamic range of values to be encoded, improving CABAC efficiency by creating a more concentrated probability distribution that better matches the context models
2Stability of the object's composition
If degree offset is added to each vertex and face degree, then the variance in face degrees and vertex valences is reduced, but the amount of data to be encoded increases
Solution Approach 1:
The patent extracts the degree offset information (k1, k2) as separate parameters that are transmitted once per mesh structure, rather than embedding offset information with every vertex and face. This allows the degree variance reduction benefit to be achieved while minimizing the additional data volume by reusing the offset parameters across multiple degree values
3Productivity
If CABAC model is used to encode degree information, then coding efficiency is enhanced, but the computational complexity increases
Solution Approach 1:
The patent applies different context models (ctx0, ctx1, ctx2) to different ranges of degree values within the CABAC encoding process. This local adaptation allows the encoder to use more accurate probability models for specific degree ranges, improving coding efficiency while keeping the overall computational complexity manageable through selective model application
Data Source
AI summary
A method includes generating a bitstream comprising an encoded three dimensional polygon mesh in accordance with dual degree connectivity comprising, when the polygon mesh comprises at least two different face degrees, a first sequence representing a vertex degree of each vertex in the polygon mesh, and a second sequence representing a face degree of each face in the polygon mesh, where each vertex degree in the first sequence and each face degree in the second sequence is followed by a degree offset, and at least one degree corresponding to a vertex degree in the first sequence or a face degree in the second sequence is encoded in accordance with a context adaptive binary arithmetic coding (CABAC) model that encodes the at least one degree using a difference between the at least one degree and a degree mode that indicates a number of different types of face degrees.