Angular Mode Syntax for Planar Point Cloud Compression
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Solution Overview
Problem
Existing point cloud compression methods struggle to efficiently encode and decode the geometry of point clouds, particularly in non-natural environments, as they fail to exploit the planar nature of these environments, leading to inefficient data representation and increased bandwidth requirements.
Innovation Solution
The method employs a planar coding mode that identifies volumes with all child sub-volumes on one side of a plane, encoding a planar mode flag and entropy coding to signal planarity, and an angular coding mode that utilizes angular information for context determination and encoding, optimizing compression in environments with directionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional point cloud compression methods are used, then the compression can be applied to general point clouds, but the compression efficiency is insufficient for non-natural environments with planar characteristics
Solution Approach 1:
The patent implements a dynamic mode selection mechanism that adapts the coding approach based on the characteristics of the point cloud data. The system determines whether to apply angular mode or planar mode coding by analyzing the geometric properties of the point cloud, allowing the compression method to dynamically adjust to different environment types (natural vs. non-natural) and achieve optimal compression efficiency for each case
Solution Approach 2:
The patent changes the coding parameters based on the detected characteristics of the point cloud. When planar characteristics are detected in non-natural environments, the system switches to planar mode coding with specific syntax elements (planar mode flags, plane position flags) that optimize compression for flat surfaces. This parameter adaptation resolves the contradiction by maintaining high compression efficiency specifically for non-natural environments while preserving compatibility with general point clouds through the ability to switch between modes
2Productivity
If angular mode coding is used, then compression is optimized for directional data, but additional angular information must be encoded increasing data overhead
Solution Approach 1:
The patent performs preliminary determination of the coding mode (angular or planar) before actual compression based on analyzing the point cloud characteristics. By pre-assessing whether the data exhibits angular or planar properties, the system can select the appropriate coding strategy and avoid adding unnecessary syntax elements or overhead for modes that aren't suitable for the current data, thus resolving the contradiction between compression efficiency and data overhead
Solution Approach 2:
The patent applies different coding strategies to different regions or portions of the point cloud based on local characteristics. Angular mode coding with its associated overhead is applied only where directional patterns are detected, while planar mode or other methods are used in regions with different characteristics. This localized application of coding methods optimizes the balance between compression efficiency and data overhead by avoiding unnecessary overhead in regions where it isn't beneficial
3Reliability
If planar mode flag and plane position flag are encoded, then planarity information is preserved, but the encoding complexity increases
Solution Approach 1:
The patent implements a selective approach where planar mode flags and plane position flags are encoded only when planar characteristics are actually detected in the point cloud data. The system does not universally apply these flags to all coding scenarios, but rather applies them partially and selectively where needed. This resolves the contradiction by maintaining accurate planarity representation only where necessary, thereby reducing overall encoding complexity while preserving reliability for planar regions
Data Source
AI summary
Method and devices for coding point cloud data using an angular coding mode. The angular coding mode may be signaled using in an angular mode flag to signal that a volume is to be coded using the angular coding mode. The angular coding mode is applicable to planar volumes that have all of their 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 position flag. Context determination for coding may take into account angular information for child nodes or groups of child nodes of the volume relative to a location of a beam assembly that has sampled to point cloud. Characteristics of the beam assembly may be coded into a dedicated syntax in the bitstream.