Visual Axis Enrollment Through Text Reading Without Intrusive Prompts

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Solution Overview

Problem

Conventional methods for estimating the visual axis in extended reality systems require intrusive user prompts, disrupting the calibration process.

Innovation Solution

An unobtrusive method involving the display of a line of text at a known vertical location for users to read, allowing eye tracking cameras to capture images and estimate the kappa angle without explicit user prompts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods display a point and prompt the user to look at it, then the visual axis can be estimated, but the user enrollment process becomes intrusive and disruptive

Engineering Contradiction:

Improvevisual axis estimation accuracyVSAvoiduser enrollment convenience

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The system performs visual axis enrollment automatically by capturing images of the user's eyes in their natural viewing state without requiring explicit user prompts or actions. The eye tracking camera continuously monitors eye position and the processor automatically calculates the visual axis, allowing the system to enroll itself without user intervention.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system performs preliminary eye image capture and processing before the user needs to interact with the system. By pre-capturing multiple images of the user's eyes as they naturally move and pre-processing these images to establish the visual axis, the system eliminates the need for intrusive real-time prompts during actual use.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If conventional calibration processes use explicit user prompts, then the visual axis can be enrolled, but the calibration process becomes time-consuming and complex

Engineering Contradiction:

Improvecalibration accuracyVSAvoidcalibration duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system continuously captures eye images and processes them in real-time during natural user interaction, rather than pausing for separate calibration steps. The eye tracking camera continuously monitors eye position, and the processor continuously updates the visual axis calculation, making the calibration an ongoing process that occurs naturally during system operation.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system merges the visual axis enrollment process with the normal eye tracking operation. By combining the calibration function with the ongoing gaze detection function, the system performs both tasks simultaneously using the same hardware and software resources, eliminating the need for separate calibration sessions.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12461594B2Visual axis enrollment

Publication Date: 2025.11.04 APPLE INC

AI summary

In an unobtrusive visual axis enrollment process, a line of text or other content is displayed at a known vertical location and virtual depth that the user can then read. This line of text may be content that the user needs to read as part of the normal enrollment process. As the user reads the line of text, eye tracking cameras may capture images of the eye. This data may then be used to estimate a stimulus plane. The error between the estimated stimulus plane and the ground truth stimulus plane (the actual location of the line of text in virtual space) may then be used to estimate the kappa angle.