Automatic Camera Principal Point Calibration via Display Geometry
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Solution Overview
Problem
Current camera calibration methods face challenges such as human error in rotating calibration plates, inconsistency in camera intrinsic parameters due to multiple images, and a trade-off between accuracy and labor/laboratory space requirements.
Innovation Solution
An automatic principal point calibration system using a controller connected to an image capturing device and displays to dynamically generate calibration images, calculate the principal point without extrinsic parameters, and maintain camera uniformity by determining the intersection of perpendicular lines as the principal point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods use manually rotated calibration plates, then calibration can be performed, but human error and inconsistency are introduced
Solution Approach 1:
The system uses the image capturing device itself to capture images of the display, eliminating the need for manual calibration plate rotation. The display dynamically generates calibration patterns that are captured and processed automatically, making the system self-calibrating without human intervention.
Solution Approach 2:
The patent replaces the mechanical calibration plate rotation system with an electronic display system. Instead of physically rotating calibration plates, the system uses a display to dynamically generate and present calibration patterns, which are then captured by the image capturing device and processed through geometric algorithms.
2Measurement precision
If multiple images of calibration plates are taken to improve accuracy, then calibration precision improves, but camera intrinsic parameter uniformity deteriorates
Solution Approach 1:
The system performs preliminary geometric correspondence analysis between the display and image capturing device to establish the principal point and calibration parameters before actual calibration imaging. This preliminary geometric setup ensures that subsequent images are captured with consistent intrinsic parameters, avoiding the need for multiple different calibration plates that would alter parameter uniformity.
3Measurement precision
If precise world coordinate system is built with three-dimensional space, then calibration accuracy improves, but labor and space requirements increase
Solution Approach 1:
The patent extracts and focuses solely on calibrating the principal point of the image capturing device without requiring a complete three-dimensional world coordinate system. By isolating the specific calibration task to just the principal point determination through geometric correspondence, the system eliminates the need for elaborate 3D space construction while maintaining calibration accuracy.
4Stability of the object's composition
If fixed camera parameters are used for calibration, then intrinsic parameters remain unchanged, but calibration flexibility is reduced
Solution Approach 1:
The system changes the approach from modifying camera parameters to changing the geometric parameters of the calibration setup. By varying the display content and geometric correspondence relationships while keeping camera intrinsic parameters fixed, the system achieves calibration flexibility without altering camera stability.
Data Source
AI summary
A camera principal point automatic calibration system including an image acquiring device, a controller, a first display and a second display is provided, wherein the controller controls the first and second display to display parallel first line and second line. The controller selectively rotates the first and second line according to whether a first and second image line generated by the image acquiring device corresponding to the first and second line are parallel or not, and the controller calculates the principal point from parallel first image line and second image line.