3D Mesh Position Encoding Without Non-Effective Subdivision
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Solution Overview
Problem
Existing 3D mesh compression algorithms are inefficient due to non-effective subdivisions in spatial tree-based methods, which increase coded data and decrease compression efficiency, especially in multi-connected models with repeated geometric features.
Innovation Solution
The method clusters input points by spatial position and uses a spatial tree (like kd-tree or octree) with conditional encoding for subdivisions, determining if they are effective by checking if child nodes have fewer points than the parent node, and using different encoding modes based on the number of points in the parent cell to indicate effective or non-effective subdivisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spatial tree-based algorithms are used to compress spatial points, then the compression can achieve multi-resolution capability, but non-effective subdivisions increase the amount of coded data and decrease compression efficiency
Solution Approach 1:
The patent applies preliminary action by performing a test subdivision before actual encoding to determine whether a subdivision is effective. The encoder evaluates if child nodes will contain fewer points than the parent node, and only proceeds with encoding if the subdivision is effective. This preliminary evaluation prevents non-effective subdivisions from increasing coded data size, thereby maintaining compression efficiency while preserving multi-resolution capability.
2Measurement precision
If recursive subdivision is performed until each cell contains only one vertex, then precise reconstruction of point position is enabled, but the amount of coded data increases and compression ratio decreases
Solution Approach 1:
The patent performs a preliminary test subdivision to evaluate whether the subdivision will be effective before actually encoding it. By checking if child nodes contain fewer points than the parent node, the system determines whether to proceed with the subdivision. This prevents unnecessary subdivisions that would increase coded data without improving precision, thus maintaining an optimal balance between point position reconstruction precision and coded data size.
Solution Approach 2:
The patent changes the parameter of subdivision effectiveness by introducing a condition based on the number of points in child nodes versus parent nodes. Instead of blindly subdividing until each cell contains one vertex, the system dynamically adjusts the subdivision process based on the effectiveness criterion. This parameter change allows the system to stop subdivision when it becomes non-effective, reducing coded data while maintaining sufficient precision.
3Ease of manufacture
If conventional encoding is used for all subdivisions, then the encoding process is simple, but non-effective subdivisions waste coding bits and reduce compression ratio
Solution Approach 1:
The patent applies preliminary action by evaluating subdivision effectiveness before encoding. The system performs a test to determine if a subdivision is effective (child nodes have fewer points than parent node), and based on this evaluation, selects the appropriate encoding mode. This preliminary evaluation adds minimal complexity but prevents wasting coding bits on non-effective subdivisions, thereby significantly improving compression ratio while maintaining encoding process simplicity.
Data Source
AI summary
Many 3D mesh models have a large number of small connected components that are repeated in various positions, scales and orientations. The respective positions are defined by the position of at least one reference point per component. For an enhanced encoding of the positions of the respective reference points, a given space is divided into segments and the number of points lying in each particular segment is determined. When a cell with at least n points is subdivided into child cells, an indication is added indicating if all points of a parent are in only one child cell. If so, the index of the only non-empty child node is encoded, while otherwise the number of points in one of the two child cells is decremented and encoded. The invention avoids non-effective subdivisions of a cell, and therefore improves the compression efficiency.