Multi-Camera Calibration Using a Moving 3D Marker
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Solution Overview
Problem
Existing imaging systems face challenges in calibrating external parameters of cameras disposed in different positions, leading to inaccurate three-dimensional space reconstruction and deterioration in free viewpoint video quality.
Innovation Solution
An imaging system that includes a movement controller to move a movable object with a marker within a common imaging area, an imaging controller to capture the marker by multiple cameras, and a calibrator to associate the marker as common feature points across images captured from different positions, allowing for the calibration of external camera parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large marker is used for calibration, then calibration accuracy is improved, but the complexity of the calibration setup and space requirements increase
Solution Approach 1:
The patent transitions from using a large two-dimensional marker to a small three-dimensional object with distinctive features. By utilizing the third dimension (depth/height), the calibration process achieves sufficient accuracy with much smaller objects, resolving the contradiction between marker size and calibration accuracy.
Solution Approach 2:
The patent employs objects with distinctive color patterns or reflective properties that enable accurate detection and identification by the imaging apparatus. These visual characteristics allow the system to precisely locate and track calibration objects without requiring large physical dimensions, thus maintaining calibration accuracy while reducing marker size.
2Reliability
If multiple calibration objects are used, then calibration reliability is improved, but the complexity of the calibration process increases
Solution Approach 1:
The calibration objects are designed to be automatically detected and identified by the imaging apparatus through their distinctive features. The system autonomously locates these objects in the field of view, extracts their position and orientation information, and uses this data for calibration without requiring complex manual intervention or multiple different calibration tools, thereby improving reliability while keeping the process simple.
3Ease of operation
If a movable object with marker is used for calibration, then ease of operation is improved, but control precision of the movable object becomes critical
Solution Approach 1:
The patent replaces complex mechanical positioning systems with a simpler approach: the movable object is equipped with distinctive visual features that allow the imaging apparatus to automatically determine its position and orientation through image processing. This substitution of mechanical precision requirements with optical detection and computational analysis simplifies the mechanical control requirements while maintaining high measurement precision.
Data Source
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AI summary
An imaging system (1000) that calibrates parameters of imaging apparatuses (10A to 10N) disposed in different positions includes: a movement controller (202c) that causes a movable object (600) that includes a marker (606) for use in calibration for the imaging apparatuses (10A to 10N) to move in an imaging area (A1) in a three-dimensional space, the imaging area being a common imaging area for the imaging apparatuses (10A to 10N); an imaging controller (202d) that causes the imaging apparatuses (10A to 10N) to image the marker (606); and a calibrator (202e) that calibrates external parameters of the imaging apparatuses (10A to 10N), using images captured by each of the imaging apparatuses (10A to 10N) imaging the marker (606) in each of three-dimensional positions different from one another.