Extrinsic Camera Calibration Using Synthetic Views of Arbitrary Patterns
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Solution Overview
Problem
Existing camera calibration methods require specialized markers or moving cameras, which may not be desirable due to aesthetic reasons or mobility constraints, and there is a need for a system that can calibrate a camera from a static viewpoint using arbitrary graphic patterns.
Innovation Solution
A method and system for camera calibration that uses a digital calibration image of arbitrary design embedded on a planar surface, generating synthetic views with virtual camera parameters, correlating 2D points in the captured image with virtual 3D points, and computing extrinsic parameters through feature detection and matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If specialized markers (QR-code-like markers or checkboard pattern) are used for camera calibration, then measurement precision is improved, but device complexity and aesthetic concerns worsen
Solution Approach 1:
The patent uses a digital calibration image (virtual copy) embedded on a planar surface instead of physical specialized markers. The synthetic pattern generator creates a digital representation of the calibration pattern that can be rendered and displayed on any flat surface, eliminating the need for complex physical marker designs while maintaining calibration accuracy through feature detection and matching algorithms.
2Adaptability or versatility
If a moving camera is used to map a scene and estimate poses concurrently (VSLAM), then adaptability is improved, but device complexity worsens
Solution Approach 1:
The patent performs preliminary action by embedding the calibration image on a planar surface at the calibration location before camera installation. The synthetic pattern generator and feature detection system are pre-configured to recognize this calibration pattern. When the camera captures the calibration image, the system can immediately compute extrinsic parameters without requiring complex real-time VSLAM algorithms or camera movement, thus reducing system complexity while maintaining positioning flexibility.
3Measurement precision
If specialized markers are used for camera calibration, then measurement precision is improved, but ease of operation worsens due to aesthetic reasons
Solution Approach 1:
The patent creates a universal calibration solution by embedding the calibration image on a planar surface that can serve multiple purposes. The calibration pattern can be integrated into existing signage, displays, or architectural elements, allowing the same surface to function both as an aesthetic element and as a calibration target. This multi-functionality eliminates the need for separate specialized markers and improves aesthetic compatibility while maintaining calibration accuracy.
4Ease of operation
If a static viewpoint calibration system is used, then ease of operation is improved, but measurement precision worsens
Solution Approach 1:
The patent introduces an intermediary synthetic pattern generator that creates a controlled calibration environment. The generator produces a known arbitrary graphic pattern with identifiable features at specific locations on the planar surface. This intermediary element mediates between the simple static camera setup and the need for accurate extrinsic parameter measurement, enabling precise calibration from a fixed viewpoint by providing well-defined reference features for detection and matching.
Data Source
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AI summary
A method of determining extrinsic parameters of a camera is disclosed. The method involves obtaining a digital calibration image and generating a plurality of synthetic views of the calibration image. The method also includes identifying a set of features from each synthetic view, obtaining a digital camera image of a representation of the digital calibration image and identifying the set of features in the digital camera image. The method includes comparing feature in the set of features of the digital camera image with features in the synthetic views and identifying a best match for each feature of the set of features of the digital camera image in all the features of the set of features of the synthetic views using the comparisons. The method concludes with calculating the extrinsic parameters of the camera using the virtual camera parameters of the synthetic views associated with the best matches.