In-Field Stereo Camera Calibration Using Rangefinder Feedback
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Solution Overview
Problem
Stereo imaging hardware on mobile devices for object dimensioning is affected by miscalibration, leading to inaccurate object dimension measurements due to changes in camera positions and optical components, which existing calibration methods cannot effectively address during regular operation without reference objects.
Innovation Solution
A method for in-field stereo camera calibration that involves capturing stereo image pairs, activating a rangefinder to update calibration data by detecting matching features and adjusting the rangefinder alignment, and using depth measurements to correct extrinsic and intrinsic parameters, allowing for continuous calibration during use without the need for a reference object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If stereo imaging hardware is deployed on mobile devices for object dimensioning, then portability and operational flexibility are improved, but measurement accuracy deteriorates due to miscalibration from camera position changes and environmental factors
Solution Approach 1:
The system performs preliminary calibration actions continuously in the field by capturing stereo image pairs and using rangefinder depth measurements to pre-correct extrinsic and intrinsic parameters before actual dimensioning operations, thereby maintaining accuracy despite portability-induced calibration drift
Solution Approach 2:
The system implements feedback mechanisms by continuously comparing rangefinder depth measurements with stereo vision depth estimates, using the discrepancy to iteratively adjust and refine calibration parameters, ensuring measurement accuracy is maintained throughout operational use
2Measurement precision
If traditional calibration methods are used requiring reference objects, then calibration accuracy is improved, but operational downtime and complexity increase
Solution Approach 1:
The system performs self-calibration in the field by using its own rangefinder depth measurements and stereo image pairs to automatically update calibration parameters without requiring external reference objects or operator intervention, eliminating calibration downtime
Solution Approach 2:
The rangefinder serves multiple functions: it provides depth measurements for dimensioning operations and simultaneously serves as a calibration reference for updating stereo vision parameters, eliminating the need for separate calibration procedures and reference objects
3Measurement precision
If calibration is performed frequently to maintain accuracy, then measurement precision is improved, but processing time and computational load increase
Solution Approach 1:
The system performs partial calibration updates by only adjusting specific extrinsic and intrinsic parameters that show drift, rather than performing complete recalibration of all parameters, reducing computational overhead while maintaining necessary accuracy
Solution Approach 2:
The system implements periodic calibration updates based on threshold triggers rather than continuous calibration, updating parameters only when depth measurement discrepancies exceed acceptable thresholds, thereby balancing accuracy maintenance with processing efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method improves the accuracy of object dimension measurements by continuously updating calibration data, reducing the impact of miscalibration and environmental factors, and enabling real-time correction of camera alignment and depth perception, thus maintaining reliable dimensioning capabilities without downtime.
Implementation Method 1
a depth measurement captured by the rangefinder
Data Source
AI summary
A stereo camera calibration method includes: controlling a stereo camera assembly to capture a sequence of stereo image pairs; simultaneously with each capture in the sequence, activating a rangefinder; responsive to each capture in the sequence, updating calibration data for point cloud generation by: detecting matching features in the stereo image pair, and updating a first portion of the calibration data based on the matched features; updating an alignment of the rangefinder relative to the stereo camera assembly, based on the updated first portion of the calibration data, and a detected position of a beam of the rangefinder in a first image of the stereo image pair; and updating a second portion of the calibration data based on the detected position of the beam of the rangefinder in the first image of the stereo image pair, the updated rangefinder alignment, and a depth measurement captured by the rangefinder.