Inside-Out Motion Capture Using Body-Mounted Cameras
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Solution Overview
Problem
Traditional motion capture systems are limited by the need for expensive setups, controlled lighting, and restricted capture spaces, making them unsuitable for outdoor or dynamic environments, and existing inside-out systems are either intrusive or prone to drift.
Innovation Solution
The use of body-mounted outward-looking cameras that estimate joint angles and root pose through non-linear optimization, incorporating image matching error and temporal continuity, allowing for motion capture in various environments without additional equipment and providing a sparse 3D structure of the scene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional marker-based optical motion capture systems are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent inverts the traditional outside-in approach by using inside-out body-mounted cameras that capture motion from the subject's perspective. Instead of having cameras fixed in the environment observing the subject, the cameras are mounted on the subject's body to record the environment and their own motion, thereby reducing system complexity while maintaining capture accuracy
Solution Approach 2:
The patent extracts the camera system from the environment and places it on the subject's body. By removing the requirement for complex environmental sensor arrays and controlled lighting setups, the system achieves motion capture in natural environments with simpler equipment, directly addressing the contradiction between precision and complexity
2Measurement precision
If traditional optical motion capture systems are used, then measurement precision is improved, but adaptability to different environments deteriorates
Solution Approach 1:
By inverting the capture approach to inside-out body-mounted cameras, the system eliminates the need for controlled indoor environments. The cameras capture motion by recording the environment from the subject's perspective, enabling accurate motion capture outdoors in diverse lighting conditions while maintaining precision
Solution Approach 2:
The body-mounted camera system provides universal applicability across different environments (indoor, outdoor, natural lighting, dark spaces) without requiring environment-specific equipment. The same camera setup works for various capture scenarios, enhancing environmental adaptability while preserving measurement precision
3Measurement precision
If marker-less methods with multiple synchronized video cameras are used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Instead of using multiple synchronized cameras fixed in the environment (outside-in), the patent employs a single body-mounted camera that moves with the subject (inside-out). This inversion dramatically reduces system complexity by eliminating the need for multiple synchronized camera setups while maintaining motion capture precision through alternative processing methods
4Measurement precision
If outside-in motion capture systems are used, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent inverts the traditional outside-in approach to inside-out body-mounted cameras, eliminating the need for complex environmental sensor arrays and controlled lighting. This inversion makes the system easier to operate by removing setup requirements while maintaining precision through computational methods that process images from the moving camera
Data Source
AI summary
Body-mounted cameras are used to accurately reconstruct the motion of a subject. Outward-looking cameras are attached to the limbs of the subject, and the joint angles and root pose that define the subject's configuration are estimated through a non-linear optimization, which can incorporate image matching error and temporal continuity of motion. Instrumentation of the environment is not required, allowing for motion capture over extended areas and in outdoor settings.