Octree Point Cloud Planar Mode for Sparse Occupancy Coding
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Solution Overview
Problem
Current point cloud compression methods, particularly using octree-based coding, fail to efficiently exploit the planar nature of non-natural environments, leading to suboptimal compression performance in applications like automotive vision and virtual reality, where data is often sparse and directionality is significant.
Innovation Solution
Implementing a planar coding mode that signals whether a volume is planar based on occupancy patterns, allowing for inference of occupancy bits and reduced bitstream encoding, thereby improving compression efficiency by adapting to local data characteristics and directionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If octree-based coding is used for point cloud compression, then the data can be organized and compressed, but compression performance is suboptimal when the point cloud exhibits planar characteristics
Solution Approach 1:
The encoding method dynamically adapts between octree-based coding and planar coding modes based on the characteristics of the point cloud data. The system determines whether to apply planar coding by evaluating occupancy patterns, allowing the compression algorithm to adapt its behavior to match the structural properties of the data being compressed, thereby improving efficiency for planar point clouds while maintaining compatibility with general cases
Solution Approach 2:
The invention introduces a planar mode flag and plane position flag as additional parameters to signal planar characteristics in the bitstream. By changing the encoding parameters based on detected planarity (using occupancy bit patterns), the system can switch between different coding strategies, improving compression performance for planar structures without affecting non-planar data
2Productivity
If planar coding mode is implemented to exploit directional patterns, then compression ratio improves, but encoding complexity increases
Solution Approach 1:
The system applies planar coding selectively rather than universally - only when occupancy patterns indicate planar characteristics. By using occupancy bits to determine whether planar coding is applicable, the method avoids the overhead of planar encoding for non-planar data, thereby improving compression ratio for suitable cases while limiting the increase in overall encoding complexity
Solution Approach 2:
The encoding process performs preliminary analysis of occupancy patterns before committing to planar coding mode. By evaluating the occupancy bits first and determining planarity beforehand, the system can make an informed decision about whether to apply the more complex planar encoding, thus managing complexity while capturing compression benefits when applicable
3Quantity of substance
If occupancy bits are inferred rather than encoded for planar volumes, then bitstream size reduces, but decoding accuracy must be maintained
Solution Approach 1:
The planar mode flag and plane position flag serve as intermediaries that convey information about the spatial distribution of occupied sub-volumes. By encoding these flags instead of all occupancy bits, the system reduces bitstream size while maintaining decoding accuracy - the flags act as mediators that allow the decoder to infer the correct occupancy pattern without transmitting every individual bit
4Productivity
If context-adaptive coding is used for planar mode flags, then compression efficiency improves, but computational requirements increase
Solution Approach 1:
The context-adaptive coding uses local occupancy patterns and neighboring volume information to determine the coding context for planar mode flags. By adapting the coding parameters locally based on specific characteristics of each volume and its neighbors, the system improves compression efficiency without requiring globally complex computations, thus balancing efficiency gains with computational energy consumption
Data Source
AI summary
Method and devices for coding point cloud data using a planar coding mode. The planar coding mode may be signaled using in a planar mode flag to signal that a volume is planar. A planar volume has all of its occupied child nodes on one side of a plane bisecting the volume. A planar position flag may signal which side of the volume is occupied. 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 one or more of whether a parent volume containing the volume is planar in occupancy, occupancy of a neighbouring volume at a parent depth, distance between the volume and a closest already-coded occupied volume at a same depth as the volume, plane position, if any, of the closest already-coded occupied volume, and a position of the volume within the parent volume.