Gaze Direction Determination Using Inverse Camera Transformation

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Solution Overview

Problem

Existing gaze tracking technologies face latency issues in dynamically updated 3D scenarios, leading to a poorer user experience and limited time-wise granularity for user interaction, particularly in dynamic game situations where the virtual camera's position and direction change quickly.

Innovation Solution

A method and system that determine the current gaze direction of a user by calculating a modified gaze direction based on the inverse of the time-dependent virtual camera 3D transformation, accounting for changes in the virtual camera's position and direction between sampling time points, to compensate for latency and improve user interaction accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional gaze tracking is used in dynamically updated 3D scenes, then the system is simple to implement, but latency occurs during rapid camera movements causing poor user experience

Engineering Contradiction:
Improvegaze direction accuracyVSAvoidlatency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary transformation of gaze directions using predicted camera transformations before the actual camera update occurs. By pre-calculating where the gaze should point based on anticipated camera movements, the system eliminates latency delays and provides immediate responsive feedback to user interactions in dynamic 3D scenes.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of transforming gaze directions forward with camera movements (which causes latency), the system applies inverse transformations to compensate for camera movements. By calculating the inverse of the camera's transformation matrix and applying it to the gaze direction, the system effectively 'undoes' the camera movement effect on the gaze pointer, maintaining accurate alignment with user intent despite rapid camera changes.

Inventive Principle:
Principle #13The other way round (Inversion)

2Measurement precision

If gaze tracking compensates for rapid camera movements, then user interaction accuracy improves, but device complexity increases

Engineering Contradiction:
Improvegaze point accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system uses a single transformation matrix that serves multiple purposes: it represents the camera's 3D transformation, enables prediction of future camera positions, and provides the inverse transformation for gaze compensation. This multi-functional approach maintains high measurement precision while avoiding the need for separate complex subsystems for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system continuously monitors camera transformation changes and dynamically adjusts gaze directions based on detected movements. By implementing a feedback loop that detects camera transformation updates and automatically compensates gaze pointers in real-time, the system achieves high interaction accuracy through a relatively simple adaptive mechanism rather than complex predictive models.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances user experience by providing a more fluent interaction with 3D scenes, even during rapid camera movements, by accurately estimating the user's gaze direction and reducing latency-related delays, thus improving the overall user interaction efficiency.

Implementation Method 1

This can be done, for example, by illuminating a region in which the eye is sought with infrared radiation

Methodology Applied
Scientific EffectInfrared radiation: Infrared Radiation

Implementation Method 2

light enters the eye and is reflected or absorbed and re-emitted through the pupil

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

light enters the eye and is reflected or absorbed and re-emitted through the pupil

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 4

capturing an image of the region; and detecting bright spots in the image

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11579687B2Method and system for determining a current gaze direction
Publication Date: 2023.02.14 TOBII TECH AB
  • US11579687B2 patent drawing
  • US11579687B2 patent drawing
  • US11579687B2 patent drawing

AI summary

A method for determining a current gaze direction of a user in relation to a three-dimensional (“3D”) scene, the 3D scene sampled by a rendering function to produce a two-dimensional (“2D”) projection image of the 3D scene, the sampling performed based on a virtual camera in turn being associated with a camera position and camera direction in the 3D scene. The method includes determining, by a gaze direction detection means, a first gaze direction of the user related to the 3D scene at a first gaze time point. The method includes determining a time-dependent virtual camera 3D transformation representing a change of a virtual camera position and/or virtual camera direction between the first gaze time point and a second sampling. The method includes determining the current gaze direction as a modified gaze direction calculated based on the first gaze direction and an inverse of the time-dependent virtual camera 3D transformation.