Camera Array Calibration Using Differentiable Point Targets
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Solution Overview
Problem
Conventional camera array calibration methods rely on physical calibration targets that are imperfect and introduce errors due to physical limitations, feature mismatching, limited visibility, and resolution issues.
Innovation Solution
The use of differentiable point targets, which are small, independently positionable, and uniquely identifiable, allows for accurate calibration of camera arrays by forming virtual planes that are perfectly planar and visible from multiple vantage points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If physical calibration targets are used for camera array calibration, then calibration can be performed with conventional methods, but calibration errors are introduced due to physical limitations, feature mismatching, and resolution issues
Solution Approach 1:
The patent replaces physical calibration targets with virtual calibration targets that are generated computationally. These virtual targets exist as mathematical constructs in the 3D scene rather than physical objects, eliminating all physical imperfections. The virtual targets are projected onto the image planes of multiple cameras and used for calibration computations, achieving perfect geometric precision without manufacturing tolerances or physical degradation.
Solution Approach 2:
The patent substitutes the mechanical/physical calibration target system with a computational/virtual system. Instead of using physical objects with printed patterns that suffer from resolution limits and manufacturing errors, the system uses software-generated virtual targets with mathematically exact geometries. This replacement of physical mechanics with computational methods eliminates the source of calibration errors.
2Ease of operation
If physical calibration targets are used, then calibration can be performed, but the targets are only visible from limited vantage points and require daisy-chaining for multi-camera calibration
Solution Approach 1:
The virtual calibration targets are designed to be simultaneously visible from all camera vantage points in the array. By placing virtual targets at multiple locations in the 3D scene and projecting them onto all camera image planes, the system creates a universal calibration reference that all cameras can observe concurrently. This eliminates the need for daisy-chaining cameras through intermediate targets, as each camera can be calibrated directly against the same set of virtual targets.
3Reliability
If physical calibration targets are used, then calibration can be performed, but errors are introduced due to the targets being imperfect and having physical limitations
Solution Approach 1:
The patent creates perfect virtual copies of calibration targets in the computational domain. These virtual targets have mathematically exact geometries, positions, and orientations that can be precisely controlled and known. Unlike physical targets that have manufacturing tolerances, wear, and deformation, the virtual targets maintain perfect geometric fidelity throughout the calibration process, providing a reliable reference that does not degrade over time or with repeated use.
Data Source
AI summary
An illustrative camera calibration system may identify a first configuration of a set of differentiable point targets as depicted in a first image of a scene and a second configuration of the set of differentiable point targets as depicted in a second image of the scene. The differentiable point targets may each be independently positionable within the scene and the first and second images may be respectively captured by first and second image capture devices in accordance with first and second poses with respect to the scene, Based on the identified first and second configurations of the differentiable point targets, the camera calibration system may generate calibration parameters for a camera array that includes the first and second image capture devices. The calibration parameters may be configured to represent the first and second poses of the first and second image capture devices, Corresponding methods and systems are also disclosed.