Planar Coding Context for Octree Point Cloud Compression
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Solution Overview
Problem
Existing point cloud compression methods, particularly for non-natural environments, fail to efficiently exploit the planar nature of some environments, leading to suboptimal compression performance in uniform partitioning-based tree structures like octrees.
Innovation Solution
Implement a planar coding mode that signals planarity in volumes, allowing for improved compression by indicating whether a volume is planar and its common plane position, and uses context-adaptive coding for planar mode syntax elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform partitioning-based tree structures (octrees) are used for point cloud compression, then the coding structure is simple and regular, but compression performance is suboptimal for planar environments
Solution Approach 1:
The patent segments the coding process into two distinct modes: conventional octree mode for general cases and planar coding mode for planar environments. This segmentation allows the system to switch between different coding strategies based on the geometric characteristics of the point cloud, thereby resolving the contradiction between structural simplicity and compression performance.
Solution Approach 2:
The patent introduces dynamic mode selection that adapts the coding approach based on the detected geometric properties of the point cloud data. The system dynamically switches between octree and planar coding modes, making the compression structure flexible rather than static, which improves compression performance for planar environments while maintaining simplicity for other cases.
2Loss of information
If planar coding mode is implemented to exploit planarity, then compression efficiency improves, but device complexity increases
Solution Approach 1:
The patent applies planar coding selectively only to regions where planarity is detected, rather than uniformly across the entire point cloud. This local application of the more complex planar coding mode minimizes the overall increase in device complexity while maximizing compression efficiency in suitable regions.
Solution Approach 2:
The system includes automatic planarity detection that self-determines when and where to apply planar coding mode without requiring manual configuration. This self-service mechanism reduces the operational complexity for users while enabling the complexity benefits of planar coding where applicable.
3Ease of operation
If all occupancy bits are encoded in octree mode, then coding is straightforward, but redundant data is transmitted for unoccupied sub-volumes in planar regions
Solution Approach 1:
The patent extracts and removes redundant occupancy information for unoccupied sub-volumes in planar regions by using planar mode indicators. Instead of encoding all occupancy bits uniformly, the system extracts only the necessary information to represent planar surfaces, eliminating redundant data transmission while maintaining coding simplicity through the use of planar mode flags.
Data Source
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AI summary
A method of encoding point cloud data using a planar coding mode is disclosed. The planar coding mode may be signaled using a planar mode flag to signal that a current volume is planar. A volume is planar if all of its occupied child nodes are on one side of a plane bisecting the volume. A planar position flag may signal which side of the volume is occupied. Volume data for already-coded occupied volumes of the point cloud is tracked using a data structure stored in memory. Entropy coding may be used to code the planar mode flag and/or the planar position flag. Context determination for coding may take into account a distance between the volume and a closest already-coded occupied volume among those tracked already-coded occupied volumes that have a same index in the data structure as the current volume.