3D TOF Camera Autocalibration via Direction Vector Error Correction
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Solution Overview
Problem
3D time-of-flight (TOF) camera systems, especially those mounted on movable devices, face challenges in maintaining accurate calibration during normal operation, leading to potential deadjustment or decalibration, which affects their reliability and accuracy in measuring distances and angles.
Innovation Solution
A method that determines direction vectors and angles for objects at different instants, calculates expected and current vectors, and uses the differences to correct the camera system's optical axis, enabling continuous calibration and adjustment, even with single or multiple known objects, and allows for autocalibration or decalibration based on error magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If 3D TOF camera systems are mounted on movable devices for real-world application, then the system becomes more versatile and useful, but the calibration accuracy deteriorates due to vibrations, movements, and environmental changes during operation
Solution Approach 1:
The patent implements a feedback mechanism where the camera continuously captures images of a calibration object with known geometric features. The system compares the observed positions and orientations with expected values, calculates deviations, and automatically adjusts calibration parameters to compensate for movements and vibrations, thereby maintaining accuracy during mobile operation
Solution Approach 2:
The calibration system performs self-calibration by using its own imaging capability to detect the calibration object and automatically compute correction parameters. This self-service approach eliminates the need for external calibration equipment or manual intervention during operation, allowing the system to maintain its own calibration accuracy autonomously
2Measurement precision
If continuous calibration is performed during normal operation to maintain accuracy, then measurement precision is improved, but device complexity increases due to additional processing and computational requirements
Solution Approach 1:
The patent incorporates a calibration object with pre-defined geometric features and known spatial relationships into the system environment. This preliminary preparation allows the camera to perform rapid automated calibration by simply detecting these known features, avoiding complex real-time calibration computations and reducing processing complexity
Solution Approach 2:
The patent replaces complex mechanical calibration mechanisms with computational image processing. Instead of using physical adjustment mechanisms or external calibration equipment, the system uses algorithms to analyze images of the calibration object and compute calibration parameters, thereby reducing mechanical complexity while maintaining precision
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 enhances the security, reliability, and accuracy of 3D TOF camera systems by allowing real-time calibration and adjustment, improving measurement precision and detecting errors or decalibration, thus maintaining system performance between service operations.
Implementation Method 1
A camera system is, in particular, to be taken to comprise all 3D TOF camera systems that obtain a time-of-flight information item from the phase shift of an emitted and received radiation
Data Source
AI summary
A method for calibrating a three dimensional time-of-flight camera system mounted on a device, includes determining at a first instant a direction vector relating to an object; determining an expected direction vector and expected angle for the object to be measured at a second instant with reference to the device's assumed trajectory and optical axis of the camera; determining a current direction vector and current angle at the second instant; determining an error represented by a difference between the current direction vector and the expected direction vector; and using the error to correct the assumed direction of the main optical axis of the camera system such that said error is substantially eliminated.