Face Direction Detection Using Glasses Reflection Points
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Solution Overview
Problem
Existing driver surveillance systems face challenges in accurately tracking a driver's line of sight due to light reflection from glasses, which can obscure the cornea reflection point, degrading marketability and safety.
Innovation Solution
A method that detects the direction of glasses-worn individuals by identifying and aligning reflection points of light from the glasses to estimate the line of sight, using additional light if necessary to form four reflection points, and calculating a face direction vector based on these reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a driver surveillance system uses traditional line of sight tracking by detecting cornea reflection points, then the system can track the driver's gaze direction, but the accuracy degrades when the driver wears glasses because light reflection from the glasses obscures the cornea reflection points
Solution Approach 1:
The patent converts the harmful light reflection from glasses into a useful detection target. Instead of treating the glasses reflection as noise to be filtered out, the system detects the reflection points on the glasses surfaces and uses them to calculate the face direction vector. The method identifies four reflection points (two from each lens surface) and uses their geometric relationships to determine the optical axis of the glasses, which corresponds to the driver's line of sight direction.
2Reliability
If the system attempts to detect cornea reflection points through glasses, then line of sight tracking can be maintained, but the reliability decreases because the glasses reflection covers the cornea reflection point making it difficult to distinguish
Solution Approach 1:
The patent extracts the detection target from the cornea reflection points to the glasses reflection points. By shifting the detection focus to the glasses surfaces, the system avoids the problem of cornea reflection being obscured. The method specifically targets the reflection points on the inner and outer surfaces of the glasses lenses, which are distinct and reliably detectable even when the driver wears glasses.
3Reliability
If the system uses alternative methods to detect face direction when glasses are worn, then tracking reliability improves, but the device complexity increases due to additional detection algorithms and processing requirements
Solution Approach 1:
The patent creates a universal detection method that works for both drivers with and without glasses. The system first detects reflection points in the eye region, then determines whether these points are from the cornea or glasses surfaces. Based on this determination, it automatically selects the appropriate calculation method: using cornea reflection geometry for bare-eyed drivers or using glasses reflection geometry for drivers wearing glasses. This unified approach eliminates the need for separate detection systems.
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
Enhances the accuracy of line of sight estimation and improves safety by effectively determining the face direction even when traditional methods fail, thereby increasing marketability and enabling better emergency response.
Implementation Method 1
the glass lenses may reflect the light and consequently, the reflected light can cover the cornea reflection point
Data Source
AI summary
A method for detecting face direction of a person includes receiving a face image of the person. The method further includes determining whether the person is wearing glasses, based on the face image. The method also includes determining whether the number of reflection points of light in a glasses region of the face image is four or more at the time of detecting the glasses region. The method also includes aligning the reflection points of light in order of size, upon determining that the number of reflection points of light is four or more. The method also includes detecting two virtual images of the light, based on the aligning. The method also includes detecting a face direction vector based on the two virtual images of the light.