Point Cloud Confidence Filtering for Accurate Map Merging

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Solution Overview

Problem

Existing methods for evaluating LIDAR map data often struggle with integrating newly acquired scan frame data due to insufficient spatial quality, leading to inaccurate merging with existing maps.

Innovation Solution

A method and system that attribute spatial confidence metrics to point cloud data, discard points with low confidence, and guide users to reacquire data in areas with low confidence, utilizing inertial measurement units, visual data, and laser odometry to refine location estimates and filter out low-confidence data for improved map accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If newly acquired scan frame data is merged with existing map data, then the map coverage is improved, but the spatial accuracy deteriorates due to insufficient spatial quality

Engineering Contradiction:
Improvemap coverageVSAvoidspatial accuracy
Core Design Contradiction:
Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent applies local quality by evaluating and filtering point cloud data at the individual point level using spatial confidence metrics. Each point is assessed independently for quality characteristics such as spatial distribution, intensity values, and geometric consistency, allowing high-quality points to be merged while rejecting low-quality points. This selective filtering approach maintains spatial accuracy in the merged map while still expanding coverage through inclusion of valid points from new scan frames.

Inventive Principle:
Principle #3Local quality

2Quantity of substance

If all acquired point cloud data is included in the map, then the data completeness is improved, but the map reliability deteriorates due to low-confidence data

Engineering Contradiction:
Improvedata completenessVSAvoidmap reliability
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent employs parameter changes by introducing and evaluating multiple spatial confidence metrics that quantify the quality of point cloud data. These metrics include spatial distribution density, intensity value consistency, geometric feature validity, and deviation from expected spatial patterns. By dynamically calculating these parameters for each point and comparing them against threshold values, the system reliably distinguishes between high-confidence and low-confidence data, ensuring only reliable points are incorporated into the map while maintaining overall data completeness.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If a threshold-based filtering method is applied to reject low-confidence points, then the spatial accuracy is improved, but the data loss increases

Engineering Contradiction:
Improvespatial accuracyVSAvoiddata loss
Core Design Contradiction:
Measurement precisionVSLoss of substance

Solution Approach 1:

The patent applies partial action by implementing a multi-threshold filtering strategy rather than a single binary threshold. Multiple confidence thresholds are established (e.g., high, medium, low confidence levels), allowing the system to selectively include points based on their quality. Points above the high threshold are definitely included, points below the low threshold are definitely rejected, and points in the intermediate range are evaluated using additional criteria or included with reduced weight. This partial filtering approach maintains spatial accuracy by rejecting clearly low-quality points while minimizing data loss by preserving potentially valid points in the intermediate confidence range.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS12014533B2Methods and systems for real or near real-time point cloud map data confidence evaluation
Publication Date: 2024.06.18 CARNEGIE MELLON UNIV
  • US12014533B2 patent drawing
  • US12014533B2 patent drawing
  • US12014533B2 patent drawing

AI summary

A method includes acquiring with a scanning device a scan frame including a point cloud comprising a first plurality of points and describing a spatial characteristic of an environment, attributing each of the first plurality of points with a spatial confidence metric, discarding a portion of the first plurality of points when the spatial confidence metric of at least one of the first plurality of points is below a predefined threshold value and directing a user of the scanning device to acquire a second point cloud approximately coincident with the discarded portion of the first plurality of points.