Point Cloud Direct Coding for Isolated Octree Nodes
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Solution Overview
Problem
Current point cloud compression techniques face inefficiencies in handling large datasets and isolated points, leading to high computational burden and poor compression performance, especially in tree-based structures like octrees and KD-trees.
Innovation Solution
The method employs direct coding mode (DCM) for points within sub-volumes eligible based on occupancy data from neighboring nodes, using a flag to indicate direct coding in the bitstream and entropy encoding positional coordinates, thereby reducing computational complexity and improving compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tree-based structures (octrees, KD-trees) are used for point cloud compression, then the data can be organized hierarchically, but the computational burden increases and compression performance deteriorates
Solution Approach 1:
The patent extracts isolated points from the tree structure by identifying sub-volumes containing only a single point. These isolated points are then processed separately using direct coding instead of being forced into the hierarchical tree structure, thereby reducing computational complexity while maintaining compression effectiveness
Solution Approach 2:
The patent segments the point cloud processing into two distinct paths: (1) points within sub-volumes that have occupied sibling nodes are processed using traditional tree-based encoding, and (2) isolated points in sub-volumes with unoccupied siblings are processed using direct coding. This segmentation allows the system to avoid unnecessary computational overhead for isolated points
2Loss of information
If traditional occupancy coding is used for all points, then the compression method remains uniform, but compression performance deteriorates for isolated points
Solution Approach 1:
The patent applies different coding strategies to different locations in the point cloud data structure. Specifically, isolated points (local regions with unoccupied siblings) receive direct coding with fewer bits, while points in densely populated regions continue to use traditional occupancy coding. This local differentiation optimizes compression efficiency without sacrificing accuracy
3Productivity
If direct coding is applied to all sub-volumes, then coding time decreases, but compression performance deteriorates due to loss of tree structure benefits
Solution Approach 1:
The patent dynamically selects the coding method based on the local characteristics of each sub-volume. The decision to use direct coding or traditional occupancy coding is made adaptively for each sub-volume based on whether its sibling nodes are occupied. This dynamic approach allows the system to optimize for speed where appropriate while preserving compression quality where needed
Data Source
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AI summary
Methods and devices for coding point clouds using direct coding mode to code coordinates of a point within a sub-volume associated with a current node instead of a pattern of occupancy for child nodes. Eligibility for use of direct coding is based on occupancy data from another node. If eligible, then a flag is represented in the bitstream to signal whether direct coding is applied to points in the sub-volume or not.