Monocular Head Tracking via Elliptical Cylinder Modeling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current head-tracking systems rely on expensive and cumbersome equipment with complex calibration procedures, making them impractical for widespread use in applications that require accurate head position and orientation estimation.
Innovation Solution
A method that processes a sequence of raster images to model the human head as an elliptical cylinder, allowing for automatic calibration and estimation of head motion using natural landmarks, enabling accurate head position and orientation tracking with commodity equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If accelerometers and gyros are mounted to the head for direct measurement, then head position and orientation can be accurately tracked, but the system becomes expensive and cumbersome
Solution Approach 1:
The patent replaces the mechanical sensor-based head tracking system (accelerometers and gyros mounted on the head) with an optical system using a single camera to capture images of the head. The head position and orientation are determined by analyzing the image sequence and tracking the movement of the head through the field of view, eliminating the need for complex mechanical sensors and mounting equipment.
Solution Approach 2:
The patent creates a simplified copy or representation of the head's motion through image processing. Instead of directly measuring head motion with sensors, the system captures visual copies (images) of the head at different positions and orientations, then processes these images to extract motion information. This copying approach allows accurate tracking without the physical complexity of sensor mounting.
2Measurement precision
If cameras observe carefully-placed marks on the subject's head for indirect measurement, then head position can be tracked, but the calibration procedure becomes complex and difficult
Solution Approach 1:
The system uses the head itself as the target for tracking, eliminating the need for separate calibration marks or artifacts. The head's natural features and movement provide the calibration information, allowing the system to automatically determine head position and orientation without requiring external calibration objects or complex calibration procedures. The head essentially calibrates itself through its natural motion.
Solution Approach 2:
The patent extracts the calibration information directly from the head's movement and appearance in the images, rather than requiring separate calibration marks. By analyzing the head's position, orientation, and movement patterns in the image sequence, the system extracts the necessary calibration data to accurately track head motion without needing carefully-placed marks or complex calibration setup.
3Device complexity
If commodity equipment is used for head tracking, then cost is reduced, but accuracy and reliability may be compromised
Solution Approach 1:
The patent segments the head tracking task into distinct processing stages: image capture, image processing to extract head position and orientation, and motion estimation. By breaking down the complex task into manageable segments, the system can use simple commodity cameras for image capture while employing sophisticated algorithms in the processing stages to maintain high accuracy. This segmentation allows cost reduction in hardware without sacrificing overall system accuracy.
Data Source
AI summary
A subject's head position and motion can be tracked by analyzing a series of frames from a monocular camera and mapping distinguishing points visible in the frames onto an elliptical cylinder. The tracking data can be used to control a physical pan/tilt actuator or to reconfigure/reposition virtual objects, images of which can be synthesized and displayed, or composited back into the original frames and displayed.