Panoramic Stereo Camera Array Calibration Without Overlapping Views
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Solution Overview
Problem
Conventional camera calibration methods fail when cameras have a small or no overlapping field of view, leading to inaccurate spatial relationship determination and algorithm failures in panoramic stereo video systems.
Innovation Solution
A method using structure from motion to calibrate camera arrays by having cameras capture images simultaneously at different positions, eliminating the need for an overlapping field of view and allowing for independent estimation of rotations and translations, thereby enabling efficient and accurate calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional calibration methods are used, then calibration accuracy is improved when cameras have large overlapping FOV, but calibration fails when cameras have small or no overlapping FOV
Solution Approach 1:
The patent introduces a motion capture system and motion data as an intermediary element that mediates the calibration process. Instead of relying on visual overlap between cameras, the system uses independently measured motion data (from markers or inertial sensors) as a mediator to establish the spatial relationship between cameras. This intermediary allows calibration to proceed even when camera fields of view do not overlap, as the motion data provides an alternative reference frame for determining camera positions and orientations.
2Adaptability or versatility
If cameras are placed back-to-back or with no overlapping FOV, then device complexity is reduced and new applications are enabled, but conventional calibration methods fail
Solution Approach 1:
The patent replaces the visual-geometry-based calibration mechanism (which relies on detecting common features in overlapping FOVs) with a motion-based calibration mechanism. By substituting the mechanical/visual inspection method with motion capture technology (using markers tracked by multiple cameras or inertial measurement units), the system can determine camera extrinsic parameters without requiring visual overlap between camera fields of view. This substitution enables back-to-back and other non-overlapping configurations while maintaining calibration accuracy.
3Measurement precision
If overlapping FOV is required for calibration, then calibration accuracy is maintained, but loss of time occurs due to repositioning and multiple captures
Solution Approach 1:
The patent performs preliminary action by capturing motion data (marker positions or inertial sensor readings) during the camera exposure time itself, rather than requiring separate calibration procedures. The motion capture system continuously tracks markers or measures inertial parameters throughout the video capture process, so that calibration data is collected as a byproduct of normal operation. This preliminary collection of motion information eliminates the need for time-consuming repositioning of cameras or multiple separate calibration captures, significantly reducing calibration time while maintaining precision.
Data Source
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AI summary
A method of calibrating a camera array comprising a plurality of cameras configured to capture a plurality of images to generate a panorama, wherein the relative positions among the plurality of cameras are constant, the method comprising: moving the camera array from a first position to a second position; measuring a homogeneous transformation matrix of a reference point on the camera array between the first position and the second position; capturing images at the first position and the second position by a first camera and a second camera on the camera array; and determining a homogenous transformation matrix between the first camera and the second camera based on the images captured by the first camera and the second camera at the first position and the second position. The method further comprises identifying a feature in the images taken by the first camera at the first position and the second position, and estimating a rotation of the first camera from the first position to the second position based on the feature.