Kinematic Mount Calibrates Optical Center Offset
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Solution Overview
Problem
The challenge lies in accurately calibrating the physical alignment between a camera's lens and on-board image sensor to minimize distortion, which is often costly and inefficient due to misalignment causes like non-uniform lens materials and misalignment during assembly, limiting the effectiveness of software-based corrections.
Innovation Solution
A kinematic mount is used to calibrate the alignment by determining the position and orientation of the lens barrel relative to the image sensor, measuring optical center offsets, and storing these values for image processing to correct distortions during image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If physical alignment calibration is performed during camera assembly using fixtures, then alignment accuracy is improved, but operational costs and device complexity increase
Solution Approach 1:
The patent replaces mechanical alignment fixtures with a software-based calibration system. Instead of using physical fixtures to mechanically align the lens barrel with the image sensor during assembly, the system uses captured images and computational algorithms to determine and correct alignment offsets. This substitution eliminates the need for expensive mechanical calibration equipment while achieving comparable or superior alignment accuracy through software processing.
2Manufacturing precision
If physical alignment calibration is performed during camera assembly, then alignment accuracy is improved, but device complexity and process difficulty increase
Solution Approach 1:
The patent replaces complex mechanical alignment fixtures with a software-based calibration system. Instead of using physical fixtures to mechanically align the lens barrel with the image sensor during assembly, the system uses captured images and computational algorithms to determine and correct alignment offsets. This substitution eliminates the need for expensive mechanical calibration equipment while achieving comparable or superior alignment accuracy through software processing.
Solution Approach 2:
The calibration system is self-calibrating by using the camera's own image sensor and lens to capture test images and compute alignment offsets. The system automatically determines the optical center position and calculates correction parameters without requiring external calibration equipment or manual intervention. This self-service approach simplifies the calibration process and reduces operational complexity.
3Ease of manufacture
If software-based distortion correction is used, then operational costs are reduced, but correction effectiveness is limited compared to physical alignment adjustment
Solution Approach 1:
The patent creates a digital model (copy) of the optical distortion by capturing test images and computing an offset map that represents the misalignment between the lens optical center and the image sensor. This digital copy of the distortion characteristics is then used to generate correction parameters that compensate for the physical misalignment. By working with a digital representation of the problem, the system achieves effective correction without requiring physical realignment of the optical components.
Solution Approach 2:
The patent changes the approach from physically adjusting alignment parameters to modifying image processing parameters. Instead of mechanically repositioning the lens or sensor to achieve perfect alignment, the system captures the actual alignment state and applies computational parameter changes to the image data. This includes calculating offset values and applying geometric transformations to correct distortion, thereby achieving effective alignment through software parameter adjustment rather than physical modification.
Data Source
AI summary
Systems and methods are provided for calibrating camera and measuring offsets for reducing distortions on images. The calibrating includes aligning an on-board image sensor and a lens barrel using a kinematic mount and affixing the onboard image sensor and the lens barrel to assemble a camera. The kinematic mount provides a predetermined number of degrees of freedom in aligning the on-board image sensor and the lens barrel. A device embeds the camera. The measuring includes receiving the camera in the kinematic mount and measuring an opposing pair of offset values as measured optical centers from the lens optical axis to the image sensor pointing reference at yaw orientations of the camera at 0 degree and 180 degrees. The method determines a total offset value by taking an average of the pair and canceling the rotationally symmetrical error. The method uses the offset value for reducing distortions on images by de-warping.