Eye Tracking Calibration Using Polygon Grid Interpolation
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Solution Overview
Problem
Conventional eye tracking systems for Near-Eye-Display (NED) devices are computationally intensive during calibration, consuming significant resources and impacting performance on compact systems, and struggle to accurately track user gaze in real-time, leading to potential motion sickness and suboptimal user experience.
Innovation Solution
A user-specific calibration method is implemented where a NED device presents virtual stimuli randomly or pseudo-randomly to capture eye tracking data, forming a polygon grid from calibration ellipse centers to interpolate real-time gaze direction, using proportionality factors based on distances within the grid to determine the user's optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional eye tracking calibration is performed using refined anatomical models, then measurement precision of user gaze is improved, but use of energy and computational resources increases significantly
Solution Approach 1:
The calibration process is segmented into two distinct phases: an initial comprehensive calibration phase that establishes a lookup table, and a real-time operation phase that uses pre-computed data. This segmentation allows the computationally intensive model refinement to occur only once during calibration, while real-time gaze tracking uses lightweight interpolation queries on the pre-built lookup table, dramatically reducing ongoing computational resource consumption.
Solution Approach 2:
The system performs preliminary calibration actions before real-time operation by pre-computing the anatomical model and storing calibration data in a lookup table. This preliminary action captures all the computationally intensive processing needed for model refinement, so that during actual use, the system only needs to perform simple data retrieval and interpolation operations, minimizing real-time energy consumption.
2Measurement precision
If real-time gaze tracking is performed using refined anatomical models, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system segments computational tasks between calibration time and runtime. During calibration, complex anatomical modeling is performed offline to create a lookup table. During runtime, only simple interpolation operations are needed, reducing real-time computational complexity while preserving measurement precision through the use of pre-computed anatomical data.
Solution Approach 2:
Instead of performing complex anatomical model calculations in real-time, the system creates a simplified copy or representation of the calibrated data in the form of a lookup table. This copy contains all necessary calibration information in a format that enables fast, simple interpolation operations during real-time gaze tracking, reducing device complexity while maintaining accuracy.
3Measurement precision
If calibration data is collected using multiple virtual stimuli, then measurement precision of ellipse centers is improved, but loss of time during calibration increases
Solution Approach 1:
The system merges multiple calibration data points collected from different virtual stimuli into a single comprehensive lookup table. By combining information from multiple stimuli presentations into one integrated calibration structure, the system achieves high measurement precision through aggregated data while enabling efficient real-time operation through unified data access, effectively managing the trade-off between calibration thoroughness and operational efficiency.
Data Source
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AI summary
Technologies for performing user-specific calibration of eye tracking systems for Near-Eye- Display (NED) devices. The NED device may sequentially present different virtual stimuli to a user while concurrently capturing instances of eye tracking data. The eye tracking data reveals calibration ellipse centers that uniquely correspond to individual virtual stimuli. The calibration ellipse centers may be used define a polygon grid in association with a sensor plane. The resulting polygon grid is used during operation to interpolate the real-time gaze direction of the user. For example, a real-time instance of eye tracking data may be analyzed to determine which particular polygon of the polygon grid a real-time ellipse center falls within. Then, distances between the real-time ellipse center and the vertices of the particular polygon may be determined. A proportionality factor is then determined based on these distances and is used to interpolate the real-time eye gaze of the user.