Imaging System Calibration via Dual-Mode Photogrammetry
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Solution Overview
Problem
Existing imaging systems used in underwater surveying and inspection face challenges in maintaining precision and accuracy due to mechanical deviations, thermal changes, pressure effects, and variations in water refractive indices, which limit their capability to deliver reliable real-world measurements.
Innovation Solution
A method and system for calibrating imaging systems by processing image data to account for deviations, using sequential and dual-mode laser and optical imaging systems, and applying photogrammetric and machine vision techniques to determine and correct calibration parameters, allowing for real-time or post-processing compensation of errors in relative positions of imaging devices and structured light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pre-calibration of component positions is performed, then the imaging system can be set up for operation, but mechanical movement, thermal changes, pressure effects, and refractive index variations cause substantial deviations from the pre-calibrated positions, reducing measurement precision
Solution Approach 1:
The system performs preliminary calibration in a controlled environment (air or water tank) to establish initial calibration parameters, then applies real-time compensation during actual operation to account for environmental deviations. This preliminary setup provides a baseline that can be adjusted dynamically.
Solution Approach 2:
The system continuously monitors actual component positions and environmental conditions, then feeds this information back to adjust calibration parameters in real-time. This closed-loop feedback mechanism compensates for mechanical movements, thermal changes, pressure effects, and refractive index variations that deviate from pre-calibration conditions.
2Measurement precision
If image data is processed after collection to remove deviation effects, then measurement accuracy improves, but processing time increases and real-time measurement capability is reduced
Solution Approach 1:
The system applies partial correction in real-time by compensating for the most significant deviation factors immediately, while more comprehensive processing can be performed later on stored data. This allows for acceptable real-time performance with option for enhanced accuracy through additional processing.
Solution Approach 2:
Calibration parameters and compensation algorithms are pre-computed and stored based on characterized environmental effects. During real-time operation, the system applies these pre-prepared corrections rapidly without requiring complex real-time calculations, thus minimizing processing time while maintaining accuracy.
3Adaptability or versatility
If sequential laser and optical imaging systems are used, then calibration can be performed using available image data, but the complexity of coordinating multiple imaging modes increases system complexity
Solution Approach 1:
The system merges laser range data with optical imaging data into a unified calibration framework. By combining these different imaging modes and treating them within a single photogrammetric model, the system leverages the complementary strengths of each mode while reducing overall coordination complexity through integration.
Solution Approach 2:
The calibration system is designed to be universal, accommodating multiple imaging modes (laser and optical) through a common photogrammetric approach. This multi-functional calibration framework can handle different data types and imaging configurations without requiring separate calibration procedures for each mode.
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 approach enables improved precision and accuracy in underwater measurements by iteratively solving for calibration parameters, converging 3D data sets, and compensating for environmental factors, thereby enhancing the reliability and efficiency of imaging systems in subsea environments.
Implementation Method 1
generating a photogrammetric model of the broad light source image data and a photogrammetric model of the structured light source image data
Implementation Method 2
Underwater 3D Laser imaging systems using laser triangulation requires accurate calibration of the relative positions of the laser and camera systems in order to compute the XYZ position of the laser points
Data Source
AI summary
Provided are a method and system for calibrating parameters of an imaging system comprising at least one imaging device and broad and structured light sources, the method comprising: the at least one imaging device sequentially capturing broad light source image data and structured light source image data of one or more scenes using the broad and structured light sources, respectively; generating a photogrammetric model of the broad light source image data and a photogrammetric model of the structured light source image data using respective coordinates of the broad and structured light source image data; determining corresponding features in the respective photogrammetric models; iteratively solving parameters of the imaging system to correct variations between corresponding features in the respective photogrammetric models, converge the models and obtain calibration parameters; and applying the calibration parameters to the imaging system to compensate for errors in the relative positions of the imaging device and structured light source.