Sight Line Estimation Using Corneal Refraction Correction
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Solution Overview
Problem
Existing sight line direction estimation techniques require complex device configurations and fail to accurately account for the refraction caused by the cornea, leading to inaccuracies in estimating the sight line direction of a person.
Innovation Solution
A sight line direction estimation device that captures an image of a person's head, calculates the eyeball and pupil center positions, and derives the apparent sight line direction using a predetermined corresponding relationship to estimate the actual sight line direction, thereby simplifying the configuration and accounting for corneal refraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sight line direction is estimated using the image obtained by capturing an image of the eyes of the user, then the device configuration can be simplified, but the measurement precision deteriorates due to corneal refraction influence
Solution Approach 1:
The patent introduces a corneal refraction model as an intermediary computational layer between the captured eye image and the final sight line direction estimation. This model accounts for the optical refraction effects in the cornea, allowing the system to maintain a simple single-camera configuration while achieving accurate sight line estimation by correcting for refraction-induced errors in the apparent pupil position
Solution Approach 2:
The patent transforms the apparent pupil center position (which is distorted by corneal refraction) into the actual pupil center position by applying refraction correction calculations. This parameter transformation compensates for the optical distortion, enabling accurate sight line direction estimation without requiring complex hardware configurations
2Measurement precision
If the technique of JP 2011-217764A is used to correct sight line error, then the measurement precision improves, but the device complexity increases due to requiring multiple devices
Solution Approach 1:
The patent combines the functions of the sight line detection device and the eye imaging device into a single integrated system. By using one camera to capture both the eye image and the reflected light from the cornea, and by performing combined processing of apparent pupil position and corneal reflection data, the system achieves accurate sight line estimation without requiring separate dedicated devices
3Measurement precision
If the user must gaze at the camera for estimation, then the measurement precision improves, but the ease of operation deteriorates due to operational complexity
Solution Approach 1:
The patent enables the system to automatically capture the user's eye image and perform sight line direction estimation without requiring the user to actively gaze at the camera or perform specific actions. The system processes the captured image data and refraction corrections autonomously, making the operation simple and natural for the user
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
The device estimates the sight line direction with high accuracy by considering the influence of corneal refraction, achieving precise results with a simpler configuration compared to existing methods.
Implementation Method 1
a sight line direction estimation device that captures an image of a person's head, calculates the eyeball and pupil center positions, and derives the apparent sight line direction using a predetermined corresponding relationship to estimate the actual sight line direction, thereby simplifying the configuration and accounting for corneal refraction
Implementation Method 2
there is room of improvement in estimating the sight line direction of the person with high accuracy... by considering the influence caused by the refraction caused by a cornea of the eyeball
Data Source
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AI summary
A sight line direction estimation device (10) includes: an imaging unit that captures an image of a head portion including an eyeball of a person; an apparent sight line direction derivation unit (102) that derives an apparent sight line direction connecting a center position of the eyeball and an apparent pupil center position on a surface of the eyeball corresponding to a pupil center position based on the image captured by the imaging unit; and a sight line direction estimation unit (108) that estimates an actual sight line direction of the person based on a predetermined corresponding relationship between an actual sight line direction and the apparent sight line direction and the apparent sight line direction derived by the sight line direction derivation unit.