3DoF Sensor Calibration via Camera Tracking for XR
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Solution Overview
Problem
Existing tracking systems for extended reality (XR) applications, such as augmented reality (AR), virtual reality (VR), and mixed reality (MR), face challenges in calibrating the accumulative error of three degree-of-freedom (3DoF) devices, which can lead to measurement distortions and a degraded user experience.
Innovation Solution
A tracking system and method that utilize a 3DoF device, a camera, and a processor to calibrate the accumulative error of the 3DoF sensor in the background. The system tracks a static target pose, such as a calibration pose, to adjust the sensor's alignment with the user's body, thereby correcting the error without interrupting the user's experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the 3DoF sensor is calibrated using traditional methods, then the measurement precision is improved, but the user experience is degraded due to interruptions and loss of immersion
Solution Approach 1:
The system performs calibration actions automatically in the background without requiring user initiation or interruption. The processor continuously monitors tracking data and executes calibration when conditions are favorable, resolving the contradiction by performing the necessary calibration action preliminarily and automatically rather than requiring explicit user action that would break immersion
Solution Approach 2:
The calibration system serves itself by automatically detecting when calibration is needed and performing the calibration without external user intervention. The processor monitors tracking results and autonomously executes calibration routines, allowing the system to maintain measurement precision while preserving user experience continuity
2Measurement precision
If the 3DoF sensor calibration is performed continuously, then the measurement precision is maintained, but the processing time and computational resources are increased
Solution Approach 1:
Instead of continuous calibration, the system performs calibration periodically based on detected conditions. The processor evaluates tracking results and initiates calibration only when specific criteria are met (such as detecting a calibration pose), thereby maintaining measurement precision while significantly reducing the time and computational resources consumed compared to continuous calibration
Solution Approach 2:
The calibration frequency and timing are made dynamic rather than static. The system adapts its calibration schedule based on real-time tracking conditions, performing calibration when the user is in a detectable calibration pose and reducing calibration activity during normal operation, thus balancing precision maintenance with resource efficiency
3Measurement precision
If the calibration process is made more complex to improve accuracy, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The existing tracking camera and processor are made to serve dual purposes: normal tracking operations and calibration execution. The camera captures both gameplay footage and calibration poses, while the processor handles both game logic and calibration algorithms, thereby improving calibration accuracy without adding dedicated calibration hardware that would increase device complexity
Data Source
AI summary
A tracking system is provided. The tracking system includes a three degree-of-freedom (3DoF) device, a camera, and a processor. The 3DoF device is adapted to be mounted on a control device worn or hold on a body portion of a user. The 3DoF device is configured to obtain sensor data from a 3DoF sensor of the 3DoF device. The camera is configured to obtain camera data. The camera data comprises an image of the body portion of the user or the control device as a tracking target. The processor is configured to: track the tracking target to generate a tracking result based on the sensor data and the camera data; determine the tracking target being static or not based on the tracking result; determine a target pose of the tracking target based on the tracking result; and calibrate an accumulative error of the 3DoF sensor in background.