Variable Focus Camera Gaze Tracking Video Passthrough
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Solution Overview
Problem
Conventional video passthrough systems in head-mounted devices (HMDs) suffer from a limited depth of focus, resulting in out-of-focus or blurry images for objects within half a meter or less of the HMD.
Innovation Solution
The implementation of a variable focus camera system in HMDs, combined with gaze-based techniques using gaze tracking and depth tracking systems, to automatically focus on objects at various depths, including close objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed focus camera is used in video passthrough systems, then the system structure is simple and manufacturing is easier, but the depth of focus is limited and close objects appear blurry
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a fixed focus camera to a variable focus camera system. The camera's focal length is dynamically adjusted based on gaze tracking data, allowing the system to adapt to different viewing distances. This enables sharp imaging of both close objects (within half a meter) and distant objects by continuously modifying the camera's optical parameters in response to user gaze direction.
Solution Approach 2:
The patent implements parameter changes by modifying the camera's focal length parameter based on gaze angle measurements. The system calculates the required focal length adjustment according to the user's gaze direction and the desired focus distance, then adjusts the camera's optical parameters accordingly. This allows the camera to maintain sharp focus across a wide range of distances by continuously changing its focal length parameter.
2Manufacturing precision
If a variable focus camera with gaze-based automatic focusing is implemented, then image sharpness at all depths is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent uses gaze tracking data as an intermediary to bridge the user's viewing intent and the camera's focus adjustment. The gaze tracking subsystem provides angular information about user gaze direction, which serves as input for calculating the appropriate focal length. This intermediary mechanism simplifies the control system by using readily available gaze data rather than requiring complex depth sensing or manual focus control interfaces.
Solution Approach 2:
The patent implements a feedback loop where gaze tracking information continuously informs camera focus adjustments. The system monitors user gaze direction in real-time and automatically adjusts the camera's focal length to maintain focus on the user's point of interest. This closed-loop feedback mechanism enables automatic focusing without requiring manual intervention while maintaining image sharpness across varying distances.
3Device complexity
If conventional fixed focus lenses are used, then the device structure is simpler, but close objects within half a meter appear out of focus
Solution Approach 1:
The patent addresses the reliability issue for close objects by making the camera's focal length dynamic rather than fixed. When the user gazes at close objects (within half a meter), the system calculates the appropriate focal length adjustment and modifies the camera's optical parameters accordingly. This dynamic adjustment ensures that close objects remain sharp and in focus, eliminating the blur problem inherent in fixed focus systems while maintaining a relatively simple overall device structure.
Data Source
AI summary
Methods and apparatus for camera focusing for video passthrough devices. Gaze information from a gaze tracking subsystem, either alone or along with depth information from a depth tracking system, may be leveraged to determine depths at which to focus. Gaze information, or a combination of depth and gaze information, may be used. As an alternative, the user can manually control the focus distance. For example, a manual bifocal method may provide two focus distances (near focus and far focus.