Mono Camera Intrinsic Recalibration Under Thermal Distortion
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Solution Overview
Problem
Existing visual tracking systems, such as AR and VR devices, face challenges in accurately calibrating camera intrinsic parameters due to thermal distortions caused by heat generated by the cameras and other components, which are not accounted for in factory calibration settings.
Innovation Solution
A method for recalibrating camera intrinsic parameters in real-time by detecting thermal changes and generating a temperature-based distortion model, involving a series of interactive user operations to adjust feature points and determine new intrinsic parameters based on the camera's operating temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If factory calibration parameters are used, then the system is simple to operate and requires no additional calibration steps, but the measurement precision deteriorates under different thermal conditions from factory settings
Solution Approach 1:
The system performs preliminary thermal conditioning by displaying calibration patterns and capturing images at the actual operating temperature before final calibration. This preliminary action at the correct thermal state enables accurate intrinsic parameter calibration without requiring separate thermal compensation steps, resolving the contradiction between operational simplicity and measurement precision.
2Loss of time
If factory calibration is performed without thermal conditioning, then the calibration process is quick and simple, but the calibration accuracy deteriorates due to thermal distortions
Solution Approach 1:
The calibration process maintains continuous operation by displaying calibration patterns and capturing images in sequence without interrupting the thermal conditioning process. The system continuously captures calibration images as the camera operates at its operating temperature, eliminating the need for separate thermal stabilization periods and achieving both speed and accuracy.
3Measurement precision
If additional thermal conditioning and calibration steps are added, then the measurement precision improves under operating conditions, but the device complexity increases
Solution Approach 1:
The system merges the thermal conditioning process with the calibration process by performing both operations simultaneously. The calibration patterns are displayed and images captured while the camera is being thermally conditioned to operating temperature, combining what would traditionally be separate processes into one unified operation that achieves high precision without increasing overall complexity.
4Ease of manufacture
If calibration is performed at factory conditions, then the manufacturing process is simple, but the reliability deteriorates when operating conditions differ from factory conditions
Solution Approach 1:
The system changes the thermal parameter of the camera from factory calibration temperature to actual operating temperature during the calibration process. By performing calibration at the elevated operating temperature where the camera will actually function, the system ensures that the intrinsic parameters accurately reflect real-world conditions, significantly improving reliability without complicating the manufacturing process.
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
Enhances the accuracy of visual-inertial simultaneous localization and mapping (VI-SLAM) by correcting for thermal distortions, reducing the need for additional computing resources and improving pose estimation.
Implementation Method 1
a temperature data from the camera system, the temperature data indicating thermal distortions
Data Source
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AI summary
A method for adjusting camera intrinsic parameters of a single camera visual tracking device is described. In one aspect, a method includes accessing a temperature of a camera of the visual tracking system, detecting that the temperature of the camera exceeds a threshold, in response identifying one or more feature points that are located in a central region of an initial image, generating a graphical user interface element that instructs a user of the visual tracking system to move the visual tracking system towards a border region of the initial image, and determining intrinsic parameters of the camera based on matching pairs of the one or more detected feature points in the border region and one or more projected feature points in the border region.