Multi-Camera Rolling Shutter Synchronization via Row Offset Control
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Solution Overview
Problem
Existing image capture systems with multiple cameras face challenges in synchronizing frame captures, leading to artifacts like ghosting and blurring due to differences in capture times and camera movements, especially when cameras have different fields of capture and rolling shutters.
Innovation Solution
The system synchronizes frame captures by preventing the first camera from scanning a predefined number of rows and columns of its sensor, aligning the scan with the second camera's field of capture, using blanking factors to control when and what portions of the sensors to scan, thereby reducing time differences and improving synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple cameras with different fields of capture and rolling shutters are used to capture frames, then the coverage and imaging applications are enhanced, but synchronization errors occur leading to ghosting and blurring artifacts
Solution Approach 1:
The system performs preliminary calibration to determine the geometric relationship and relative motion between cameras before actual frame capture. This pre-established model is then used to predict and compensate for synchronization errors during runtime, allowing the system to maintain reliability while supporting diverse imaging applications.
Solution Approach 2:
The system captures reference frames from multiple cameras, detects synchronization errors through image processing, and feeds this information back to adjust the capture timing. This closed-loop feedback mechanism continuously corrects synchronization drift, maintaining reliable frame alignment despite different camera specifications and motions.
2Device complexity
If rolling shutters are used in cameras with different fields of capture, then device complexity is reduced, but time differences in pixel scanning occur causing misalignment
Solution Approach 1:
The system dynamically adjusts scanning parameters including start row offsets and scan rates for different cameras based on their specific fields of capture. By changing these parameters adaptively, the system compensates for the inherent time differences in rolling shutter scanning while maintaining device simplicity.
Solution Approach 2:
The system accepts and utilizes the asymmetric nature of different camera fields of capture and rolling shutter characteristics rather than attempting to make them uniform. It applies asymmetric compensation strategies tailored to each camera's specific properties, improving alignment accuracy without requiring symmetric hardware configurations.
3Productivity
If cameras capture frames simultaneously without compensation, then capture speed is maximized, but artifacts like ghosting and blurring occur in fused images
Solution Approach 1:
The system performs preliminary calibration to establish the geometric relationship and motion characteristics between cameras before actual capture. This pre-computed model enables real-time compensation during high-speed capture, maintaining both capture speed and image quality by predicting and correcting for synchronization errors.
Solution Approach 2:
Instead of using mechanical synchronization mechanisms that would slow down capture, the system substitutes mechanical coordination with computational compensation. It uses image processing algorithms to detect and correct misalignment after capture, achieving high-speed capture without sacrificing image quality.
Data Source
AI summary
Systems and methods for synchronizing frame captures for cameras with different fields of capture are described. An example device includes a first camera and second camera. The first camera includes a first camera sensor and a first rolling shutter. The first camera is configured to prevent scanning pixels from a first row to a row n of the first camera sensor and configured to begin sequentially scanning pixels of the row n of the first camera sensor. The second camera includes a second camera sensor and a second rolling shutter. The second camera is configured to begin sequentially scanning pixels of a first row of the second camera sensor concurrently with beginning to sequentially scan pixels of the row n of the first camera sensor. The first row of the second camera sensor corresponds to a row within a predefined number of rows after the first camera sensor's row n.