Mesh Patch Syntax for Sparse 3D Mesh Connectivity
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Solution Overview
Problem
Current methods for compressing 3D meshes in V-PCC are inefficient for sparse point clouds and lack mechanisms to transmit connectivity, with existing solutions either requiring dense point clouds or missing triangle face attributes.
Innovation Solution
New syntax elements are introduced to extend the V3C standard, enabling encoding of meshes using patches that project connected triangles to a 2D surface, allowing for different encoding methods for vertex positions and connectivity, including explicit, embedded, and external encoding, and supporting triangle strips and tracked patches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If V-PCC projection-based method is used for mesh compression, then compression efficiency is improved, but connectivity information is lost
Solution Approach 1:
The patent segments the mesh data into two distinct components: geometry data (vertex positions) and connectivity data (triangle face indices). This segmentation allows each component to be encoded using the most appropriate method - geometry using V-PCC projection for compression efficiency, and connectivity using dedicated mesh compression techniques to preserve topological information.
Solution Approach 2:
The patent merges the V-PCC projection-based geometry encoding with mesh-specific connectivity encoding into a unified coding framework. The geometry and connectivity data are combined in the bitstream to reconstruct complete mesh structures, achieving both compression efficiency and connectivity preservation.
2Productivity
If dense point clouds are used for V-PCC encoding, then encoding efficiency is improved, but sparsity is lost
Solution Approach 1:
The patent introduces dynamic patch configuration where patch sizes and densities can be adjusted based on the local characteristics of the mesh surface. This allows the encoding to adapt to varying sparsity levels across different regions, maintaining efficiency while preserving the inherent sparsity structure where applicable.
Solution Approach 2:
The patent applies different encoding strategies to different regions of the mesh based on local characteristics. Areas with high point density use one encoding approach, while sparse regions use another, allowing the system to optimize for encoding efficiency in dense areas while preserving sparsity information in sparse areas.
3Adaptability or versatility
If RAW patch data is used to encode vertex positions, then sparse point clouds are supported, but compression efficiency decreases
Solution Approach 1:
The patent introduces configurable parameters that allow switching between different encoding modes for vertex positions. When sparsity is detected, the system can switch from standard V-PCC projection to RAW patch data encoding, and vice versa, optimizing for either sparsity support or compression efficiency based on the input data characteristics.
4Reliability
If mesh connectivity is encoded separately from geometry, then connectivity is preserved, but device complexity increases
Solution Approach 1:
The patent designs a unified encoding framework that handles both geometry and connectivity encoding within a single processing pipeline. The same encoder structure can process different data types (geometry, connectivity, attributes) by switching between different coding modes, reducing overall system complexity while maintaining connectivity preservation.
Data Source
AI summary
New syntax elements are used to extend patch types, and the syntax is added to the V3C standard. The new syntax defines patches that encode meshes by projecting connected triangles to a 2D surface, patches that encode triangles or triangle strips without any projection, or patches that are tracked over time and are encoded by projecting connected triangles to a 2D surface. Furthermore, the syntax allows for different ways of coding the mesh-specific information. For instance, the syntax enables three different encoding methods for the vertex position: explicit (directly added to the atlas stream), embedded on video data (occupancy map data), or encoded using an external mesh encoder.