Clipped Laser Indices for Predictive Point Cloud Coding

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Solution Overview

Problem

In predictive geometry coding for point cloud compression, the reconstructed laser index often exceeds the valid range due to rounding errors, leading to undefined behavior in the decoder.

Innovation Solution

Constrain the reconstructed laser index within the valid range by adjusting the encoding of the residual laser index to ensure it remains within the permissible limits, either at the encoder or decoder side.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If predictive geometry coding is used to compress point clouds, then compression efficiency is improved, but rounding errors cause reconstructed laser indices to exceed valid ranges leading to undefined decoder behavior

Engineering Contradiction:

Improvecompression efficiencyVSAvoiddecoder behavior validity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The encoder applies preliminary anti-action by constraining the residual laser index to ensure that when added to the predicted laser index, the result remains within the valid range. This preventive measure stops the harmful effect (invalid laser index) before it can occur during decoding.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The invention changes the parameter of the residual laser index by modifying its encoding based on the predicted laser index and the valid range. The residual is adjusted dynamically to ensure the reconstructed index stays within acceptable limits, transforming the harmful rounding error into a controlled parameter adjustment.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the laser index is constrained to remain within valid range, then decoder behavior becomes defined and reliable, but the encoding process becomes more complex

Engineering Contradiction:

Improvedecoder behavior validityVSAvoidencoding process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The encoder performs preliminary action by calculating and applying the constraint on the residual laser index before encoding. This advance preparation ensures that the decoded laser index will be valid, avoiding the need for complex error correction during decoding.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The encoding process incorporates feedback by using the predicted laser index to determine the appropriate constraint for the residual. This feedback mechanism ensures that the residual is adjusted according to the specific context, maintaining reliability while managing complexity through adaptive constraint application.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12430807B2Clipping laser indices in predictive geometry coding for point cloud compression

Publication Date: 2025.09.30 QUALCOMM INC

AI summary

A method of encoding a point cloud includes determining, by one or more processors, a quantity of lasers used to capture light detection and ranging (LIDAR) data that represents the point cloud; and encoding, by the one or more processors, a laser index for a current node of the point cloud, wherein encoding the laser index comprises: obtaining a predicted laser index value of the current node; determining a residual laser index value for the current node, wherein determining the residual laser index value comprises constraining a sum of the residual laser index value and the predicted laser index value to be less than or equal to the determined quantity of lasers minus one; and encoding, in a bitstream, one or more syntax elements that represent the residual laser index value.