Eye Tracking Correction for Head-Mounted Display Motion
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Solution Overview
Problem
Existing gaze tracking systems in head-mountable display units (HMDs) face challenges in accurately tracking eye movements due to the proximity of cameras to the user's eyes, leading to potential misinterpretation of head-mounted arrangement motion as eye motion, which can result in erroneous inputs and incorrect focus regions during foveal rendering.
Innovation Solution
A method is introduced to differentiate between eye motion and head-mounted arrangement motion by detecting and correcting for the relative motion of the arrangement on the user's head, using a combination of sensors and image processing techniques to accurately track eye movements and apply corrections to the eye tracking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cameras are positioned close to the user's eyes in HMDs to improve tracking precision, then measurement precision is improved, but the system cannot distinguish between head-mounted arrangement motion and actual eye motion, leading to measurement errors
Solution Approach 1:
The patent segments the motion detection into two independent components: head motion detection (via sensors detecting gravitational force and linear acceleration) and eye motion detection (via cameras capturing eye images). By separating these previously conflated measurements, the system can independently process and combine them to achieve both close proximity positioning and accurate differentiation between head and eye movements.
Solution Approach 2:
The patent introduces sensor data (accelerometer and gyroscope readings) as an intermediary to mediate between the camera's close proximity positioning and the need for accurate eye motion detection. The sensor data serves as a reference frame that allows the system to subtract head motion from the combined motion signal, isolating the pure eye motion component for accurate tracking.
2Adaptability or versatility
If the head-mounted arrangement moves relative to the user's head, then the system can be adjusted to different positions, but this relative motion is misinterpreted as eye motion, causing erroneous inputs
Solution Approach 1:
The patent implements a feedback loop where sensor data continuously monitors head-mounted arrangement motion and feeds this information back to the eye tracking processing. The system uses this feedback to dynamically correct the eye position calculations in real-time, compensating for any relative motion between the arrangement and the user's head, thereby maintaining measurement precision despite positioning flexibility.
3Measurement precision
If sensors are added to detect head motion and correct eye tracking, then tracking accuracy is improved, but device complexity increases
Solution Approach 1:
The patent leverages the existing multi-functionality of HMD sensors, which are already present for other purposes (motion tracking, navigation, etc.). By repurposing these existing sensors for the additional function of head motion compensation in eye tracking, the system achieves improved accuracy without adding dedicated hardware solely for this purpose, thereby limiting the increase in device complexity.
Data Source
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AI summary
A system configured to perform an eye tracking process using a head-mountable eye-tracking arrangement, the system comprising an eye tracking unit, located on the head-mountable arrangement, operable to detect motion of one or both of the user's eyes, a relative motion identification unit operable to identify motion of the head-mountable arrangement relative to the user's head, and a correction unit operable to determine a correction to the eye tracking process in dependence upon the identified motion of the user's head relative to the head-mountable arrangement.