Point Cloud Attribute Prediction Using Morton-Code Nearest Neighbors
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Solution Overview
Problem
The existing Geometry-based Point Cloud Compression (G-PCC) and Video-based Point Cloud Compression (V-PCC) codecs face inefficiencies in predicting attribute information due to the inability to accurately find the optimal nearest neighbor point during inter prediction, which affects codec efficiency and performance.
Innovation Solution
The proposed solution involves determining a reference point from a prediction point set using Morton code information, establishing a search range, and identifying a nearest neighbor node based on Morton code information to improve the prediction effect for attribute information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a block-based fast search algorithm is used to find nearest neighbor points, then the search speed is improved, but the prediction accuracy deteriorates because the optimal nearest neighbor point cannot be accurately found
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing Morton codes for all points in the reference frame during the encoding process. These pre-computed Morton codes are stored in a lookup structure that enables O(1) retrieval during decoding, eliminating the need for computationally intensive nearest neighbor searches during the actual prediction process.
Solution Approach 2:
The patent replaces the mechanical search process (iteratively comparing distances to find nearest neighbors) with an information-theoretic approach using Morton codes. The Morton code serves as a spatial indexing key that directly maps to neighborhood relationships, substituting complex geometric search operations with simple code lookup and comparison operations.
2Measurement precision
If the optimal nearest neighbor point is accurately found, then the prediction effect for attribute information is improved, but the codec efficiency deteriorates due to increased computational complexity
Solution Approach 1:
The patent performs the computationally intensive Morton code calculation and nearest neighbor identification in advance during the encoding process. The results are stored in lookup tables or pre-computed data structures, so that during decoding the process simply involves retrieving pre-computed values, dramatically reducing real-time computational requirements while maintaining optimal prediction accuracy.
Solution Approach 2:
The patent segments the point cloud processing into distinct phases: encoding phase where nearest neighbor relationships are established and Morton codes are computed, and decoding phase where these pre-computed relationships are utilized. This temporal segmentation allows heavy computation to be performed when data is available (encoding time) rather than during real-time processing (decoding time).
Data Source
AI summary
Provided are an encoding method and a decoding method. Regarding a node to be processed in a LOD M in a current frame, a codec can determine a reference point from a prediction point set of a reference frame for the current frame according to first Morton code information corresponding to the node to be processed, M being an integer greater than 1, and an index of a point in the prediction point set of the reference frame being determined based on Morton code information of the point; determine a search range based on second Morton code information corresponding to the reference point, and determine a nearest neighbor node corresponding to the node to be processed according to the search range; and determine a predicted attribute value corresponding to the node to be processed on the basis of a reconstruction value of the nearest neighbor node.


