3D Motion Capture Calibration via X-Ray Skeletal Alignment
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Solution Overview
Problem
Conventional 3D motion capture systems face challenges in accurately aligning skeletal movements due to the difficulty in determining the precise alignment of sensors relative to the skeleton, leading to inaccurate and misleading results, especially when assuming initial angles without precise calibration.
Innovation Solution
The integration of x-ray data to calibrate the 3D motion capture system by determining the actual orientation of bones and joints, which is then used to offset the initial skeletal alignment, providing a more accurate reference frame for tracking movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 3D motion capture systems use sensors or markers placed on the outside of the subject's body, then 3D motion visualization and data analysis become possible, but the precise alignment of sensors relative to the skeleton cannot be determined, leading to inaccurate measurement results
Solution Approach 1:
The patent introduces x-ray images as an intermediary medium to bridge the gap between external sensors and internal skeleton. The x-ray images serve as a mediator that allows direct visualization and measurement of skeletal structures, enabling accurate determination of sensor-to-skeleton alignment without requiring direct access to or penetration of the skeleton itself.
Solution Approach 2:
The patent replaces the mechanical approach of directly attaching sensors to bones (which would provide perfect alignment but is invasive and impractical) with a non-invasive imaging-based system. X-ray imaging substitutes for direct mechanical attachment, allowing remote, non-contact measurement of skeletal positions while maintaining accuracy.
2Reliability
If conventional 3D motion capture systems assume initial angles without precise calibration, then the system setup is simplified and faster, but the reference frame becomes miscalculated leading to inaccurate motion analysis
Solution Approach 1:
The patent performs preliminary calibration actions by capturing x-ray images of the subject in a known initial position before motion analysis begins. This preliminary imaging allows the system to establish an accurate reference frame for skeletal alignment and initial angles, ensuring that subsequent motion capture data is interpreted correctly relative to the proper anatomical starting position.
3Loss of information
If 3D motion capture systems use advanced sensors and technology to provide multiple viewing angles and digital data analysis, then comprehensive motion information is obtained, but the system setup takes longer and is more expensive
Solution Approach 1:
The patent makes the x-ray imaging system multi-functional by using the same x-ray equipment and initial images for multiple purposes: (1) visualizing skeletal structures, (2) determining sensor-to-skeleton alignment, (3) establishing reference frames, and (4) providing calibration data. This multi-functionality reduces the need for separate specialized equipment and simplifies the overall setup process while maintaining comprehensive motion analysis capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise skeletal alignment and movement analysis by correcting initial reference frame errors, resulting in more accurate and reliable data for motion capture systems.
Implementation Method 1
receives a portion of the subject user's body as represented in x-ray data
Data Source
AI summary
A processing device receives, from a three-dimensional (3D) motion capture system, initial data representing an initial orientation of a subject user's body in an initial position. The processing device further receives x-ray data representing at least the portion of the subject user's body in the initial position. The processing device determines an actual orientation of at least one bone or joint from the portion of the subject user's body in the initial position as represented in the x-ray data and calibrates the initial orientation of the 3D motion capture system to reflect the actual orientation of the at least one bone or joint in the initial position.