Multi-Camera Calibration Using Overlapping Marker Views
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Solution Overview
Problem
Existing methods for calibrating tracking and broadcast cameras in golf scenarios face challenges due to the lack of visible reference markers and the inability to establish a wide base between cameras, making it difficult to determine coordinate transformations accurately.
Innovation Solution
A method and apparatus using a third camera with overlapping fields of view to estimate transformations between the coordinate systems of the first and second cameras, allowing for accurate calibration without requiring visible markers by leveraging existing golf course markers and measuring distances and angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If arbitrary placement of broadcast camera and tracking sensor occurs at golf tee box, then ease of operation is improved, but measurement precision deteriorates because coordinate systems have no visible fixed points
Solution Approach 1:
The patent introduces a third camera as an intermediary device positioned at the first camera's location to capture images of ground plane markers. This intermediary camera enables the system to establish coordinate transformations between the first and second cameras by providing reference points (markers) that are visible in multiple camera fields of view, thereby resolving the measurement precision issue while maintaining operational flexibility
Solution Approach 2:
The third camera essentially creates a copy or duplicate of the first camera's position and field of view. By having the third camera capture images of the same markers that are visible to the first camera, the system can perform calibration calculations without requiring the first camera itself to see the markers, thus maintaining the first camera's arbitrary placement while achieving accurate coordinate transformation
2Ease of manufacture
If no external reference markers are added to golf course environment, then ease of manufacture is improved, but difficulty of detecting and measuring worsens
Solution Approach 1:
The patent leverages existing markers on the golf course (such as tee markers or course markers) that are already present in the environment. Instead of requiring addition of specialized calibration markers, the system uses these pre-existing markers as reference points, allowing the calibration process to serve itself using available environmental features
Solution Approach 2:
The ground plane markers serve multiple functions: they are both part of the normal golf course environment (for gameplay purposes) and serve as calibration reference points for the camera system. This multi-functionality eliminates the need for separate calibration markers while maintaining measurement capability
3Measurement precision
If wide base between cameras is established, then measurement precision is improved, but device complexity worsens due to geometrical limitations of tee box
Solution Approach 1:
The patent resolves the base distance limitation by transitioning from a two-dimensional ground plane problem to a three-dimensional solution using height differences. The third camera is positioned at a different height (vertical dimension) than the second camera, allowing coordinate transformation to be determined through vertical angle measurements rather than requiring horizontal distance separation
Data Source
AI summary
A system, a method and a calibration apparatus determine a first transformation between a first coordinate system of a first camera and a second coordinate system of a second camera by use of a third camera. The third camera captures first and second markers in its field of view. The calibration apparatus iteratively determines updated orientation components of a third transformation, between the first and third cameras. In a similar manner, the calibration apparatus iteratively determines updated orientation and translation components for a second transformation, between the first and second cameras. Furthermore, the calibration apparatus iteratively determines at least updated orientation components for the first transformation.