Scale-Aligned Angular Mode for In-Tree Point Cloud Compression
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Solution Overview
Problem
The combination of angular mode and in-tree quantization in point cloud compression results in reduced coding efficiency and loss, as the quantized bits are in a different scale space from the original points, making it ineffective to enable both simultaneously.
Innovation Solution
A technique is introduced to derive a scaled value from the quantized coordinate value without clipping, ensuring it aligns with the original point value's scale space, thereby maintaining coding efficiency when both angular mode and in-tree quantization are used together.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If in-tree quantization is enabled, then compression ratio is improved, but coding efficiency is reduced due to scale space mismatch
Solution Approach 1:
The patent changes the parameter of quantized value representation by introducing a scaled value that transforms the quantized coordinate from its original scale space into the same scale space as the original point cloud data. This parameter transformation enables the quantized values to be effectively used for context derivation in angular mode while maintaining the compression benefits of in-tree quantization.
2Productivity
If angular mode is used, then coding efficiency is improved, but effectiveness is reduced when combined with in-tree quantization due to scale space difference
Solution Approach 1:
The patent introduces a scaled value as an intermediary between the quantized coordinate and the context derivation process. This scaled value acts as a mediator that translates the quantized coordinate into the appropriate scale space, enabling effective use in angular mode context derivation while preserving the benefits of in-tree quantization.
3Speed
If quantized bits are used directly for context derivation, then processing speed is improved, but accuracy is reduced due to being in different scale space
Solution Approach 1:
The patent applies a preliminary scaling action to the quantized coordinates before they are used for context derivation in angular mode. By pre-scaling the quantized values to match the original point cloud scale space, the method ensures that subsequent context derivation operations are performed on accurately scaled data, improving both the correctness and effectiveness of the coding process.
Data Source
AI summary
A device for decoding a bitstream that includes point cloud data can be configured to determine, based on syntax signaled in the bitstream, that in-tree quantization is enabled for a node; determine, for the node based on the syntax signaled in the bitstream, that an angular mode is activated for the node; in response to in-tree quantization being enabled for the node, determine for the node a quantized value representing a coordinate position relative to an origin position; scale the quantized value without clipping to determine a scaled value representing the coordinate position relative to the origin position; and determine a context for context decoding a plane position syntax element for the angular mode based on the scaled value representing the coordinate position relative to the origin position.