Stereo Camera Calibration via Vanishing Point Edge Detection
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Solution Overview
Problem
Existing stereo camera systems in vehicles face challenges in accurate calibration due to misalignment caused by improper attachment, external vibrations, or changes over time, leading to inaccurate vanishing point calculations from lane markings, which affects distance measurement accuracy.
Innovation Solution
An image processing apparatus and method that includes a stereo camera system with edge detection, determination units, and calibration data calculation to select and calibrate images based on straight line criteria, ensuring accurate vanishing point calculation and calibration by excluding images with curved or partially absent lane markings, and using statistical values to match calibration data between benchmark and reference images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vanishing point calculation is performed using lane markings in stereo images, then distance measurement capability is enabled, but measurement precision deteriorates due to camera misalignment from improper attachment, external vibration, or shock
Solution Approach 1:
The system performs preliminary calibration by detecting the vanishing point from lane markings in the captured images and calculating misalignment amounts before actual distance measurement. This preliminary alignment correction ensures that subsequent measurements are performed on properly aligned stereo images, resolving the contradiction between enabling distance measurement and maintaining measurement precision despite camera misalignment
Solution Approach 2:
The system continuously monitors camera alignment by detecting vanishing points and calculates misalignment amounts, then feeds this information back to correct the stereo image alignment. This closed-loop feedback mechanism maintains measurement precision by dynamically compensating for camera misalignment caused by vibration, shock, or improper attachment
2Measurement precision
If vanishing point is calculated from intersection of lane marking extensions, then calibration can be performed, but measurement precision deteriorates when lane markings are curved or partially absent
Solution Approach 1:
Instead of requiring complete and perfectly straight lane markings, the system uses partial lane marking segments that are visible in the image. By detecting the vanishing point from available partial markings and using statistical processing across multiple images, the system achieves accurate calibration even when lane markings are curved or partially absent, resolving the contradiction between precision and adaptability
3Ease of operation
If stereo camera system is attached to vehicle, then distance measurement function is provided, but manufacturing precision deteriorates due to misalignment from improper attachment or external vibration
Solution Approach 1:
The system performs self-calibration by automatically detecting vanishing points from lane markings in captured images and calculating the misalignment amounts. This self-service calibration mechanism eliminates the need for precise manual alignment during installation, allowing the distance measurement function to be easily implemented while automatically compensating for attachment errors and vibration-induced misalignment
Data Source
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AI summary
An image processing apparatus (12) includes an input interface (15) configured to acquire images captured by a camera (11a) and a controller (16) configured to detect an edge corresponding to at least one of two or more parallel, straight lines included in the subject of the camera (11a) from each of a plurality of frames acquired by the input interface (15), to select a frame for use by evaluating the detected edge, and to calculate calibration data for the camera (11a) on the basis of an approximate straight line corresponding to edge pixels obtained from a plurality of selected frames.