Headset Camera Fiducial Timing for Low-Light Controller Tracking
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Solution Overview
Problem
Existing augmented reality systems face challenges in accurately tracking the position and orientation of handheld controllers, particularly under varying light conditions, which affects the user's experience and the integration of virtual content with the real world.
Innovation Solution
A wearable system that alternates between headset tracking and controller tracking using exposure intervals and fiducial intervals, employing headset cameras and controller fiducials to determine the pose of the controller, and incorporates modular controllers with interchangeable components for enhanced functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the headset camera captures images with high exposure to improve image quality in low-light conditions, then the visibility of fiducials improves, but the tracking accuracy deteriorates due to motion blur and exposure timing issues
Solution Approach 1:
The system employs periodic flashing of fiducials synchronized with periodic camera exposure intervals. The fiducials flash at specific frequencies that coincide with the camera's exposure timing, ensuring that the fiducials are captured during brief high-exposure windows. This periodic synchronization allows the camera to capture bright, clear fiducial images without requiring continuously high exposure levels, thereby maintaining tracking accuracy while improving visibility in low-light conditions.
Solution Approach 2:
The system performs preliminary synchronization of fiducial flashing with camera exposure intervals before actual tracking occurs. The controller pre-establishes the timing relationship between fiducial flash events and camera exposure windows, ensuring that fiducials are guaranteed to be visible during exposure. This preliminary coordination eliminates the need for continuous high exposure and prevents motion blur by ensuring proper timing alignment.
2Use of energy by moving object
If the system alternates between headset tracking and controller tracking with different exposure intervals, then power consumption is reduced, but tracking reliability deteriorates due to potential missed detections
Solution Approach 1:
The system incorporates feedback mechanisms where the controller monitors the successful detection of fiducials during alternating tracking intervals. When fiducials are successfully captured during a controller tracking frame, the system confirms proper synchronization and continues the alternating pattern. If detections fail, the system can adjust timing parameters or increase exposure duration for that specific interval, ensuring tracking reliability is maintained while still benefiting from reduced average power consumption compared to continuous high-exposure operation.
Solution Approach 2:
The system maintains tracking reliability through periodic alternation between headset-tracking-optimized frames and controller-tracking-optimized frames. During headset tracking frames, the camera uses exposure settings optimized for general scene capture. During controller tracking frames, the camera switches to a different exposure interval synchronized with fiducial flashing, allowing for more efficient power consumption while ensuring controller tracking capability is periodically refreshed and maintained.
3Measurement precision
If multiple fiducials flash simultaneously to improve controller identification, then the signal strength increases, but the ability to distinguish between multiple controllers deteriorates
Solution Approach 1:
The system assigns different flash patterns to different controllers to enable differentiation. Each controller may have fiducials that flash at distinct frequencies, different phase offsets, or different temporal patterns. This asymmetric assignment of flash characteristics to different controllers allows the system to maintain strong detection signals while simultaneously distinguishing between multiple controllers based on their unique flash signatures.
Solution Approach 2:
The system transitions from spatial differentiation alone to temporal-dimension differentiation by introducing time-based flash patterns. Instead of relying solely on the spatial position of fiducials to distinguish controllers, the system adds a temporal dimension through synchronized flashing at different frequencies and phases. This allows multiple controllers to be distinguished even when their fiducials are spatially close, while still maintaining strong detection signals through coordinated flashing.
Data Source
AI summary
Wearable systems and method for operation thereof incorporating headset and controller localization using headset cameras and controller fiducials are disclosed. A wearable system may include a headset and a controller. The wearable system may alternate between performing headset tracking and performing controller tracking by repeatedly capturing images using a headset camera of the headset during headset tracking frames and controller tracking frames. The wearable system may cause the headset camera to capture a first exposure image an exposure above a threshold and cause the headset camera to capture a second exposure image having an exposure below the threshold. The wearable system may determine a fiducial interval during which fiducials of the controller are to flash at a fiducial frequency and a fiducial period. The wearable system may cause the fiducials to flash during the fiducial interval in accordance with the fiducial frequency and the fiducial period.