Digital Facial Measurement Calibration for Head and Gaze Alignment
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Solution Overview
Problem
Existing digital mirror systems fail to accurately measure facial features such as pupillary distance (PD) and ocular center (OC) height due to uncertainties in user head orientation and gaze alignment relative to the screen plane, leading to measurement inaccuracies.
Innovation Solution
A system and method that includes a camera, monitor screen, and processor to project a graphical target, register user head orientation, and perform calibration and registration processes to ensure accurate measurement of facial features by transforming the video stream to mimic a mirror image, using a 3D spheroid avatar and graphical overlays for alignment and measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a camera and screen are used to replace the conventional mirror for digital measurements, then automation and efficiency are improved, but measurement precision deteriorates due to uncertainties in user head orientation and gaze alignment
Solution Approach 1:
The system displays a graphical target overlay on the screen showing the desired head orientation and gaze position. The system continuously monitors user position and provides real-time feedback by adjusting the graphical target or providing visual cues (such as alignment indicators) to guide the user into the correct position, ensuring accurate measurements while maintaining automated operation
Solution Approach 2:
A graphical target overlay serves as an intermediary between the camera system and the user. This visual mediator communicates the required head orientation and gaze alignment to the user, bridging the gap between automated measurement requirements and user positioning, thereby improving measurement precision without reducing automation
2Ease of operation
If the camera is positioned above the screen to mimic a mirror image, then ease of operation is improved, but measurement precision worsens due to distorted perspective and difficulty in achieving proper alignment
Solution Approach 1:
The system acknowledges and compensates for the asymmetric camera position above the screen. By using asymmetric calibration parameters and perspective correction algorithms specific to this camera-screen geometry, the system maintains measurement precision while preserving the intuitive mirror-like user experience
Solution Approach 2:
The system dynamically adjusts measurement parameters such as field of view, focal length equivalents, and coordinate transformation matrices based on the camera's fixed position above the screen. These parameter changes compensate for the distorted perspective, allowing accurate measurements to be obtained while maintaining the ease of operation provided by the mirror-like display
Data Source
AI summary
A method for performing digital measurements by obtaining a first video stream of a user at a first distance to a camera; using an element appearing in the first video stream to generate a transformation factor to convert pixel distance in the first video stream to actual physical distance in the real world; using the transformation factor to obtain a first digital measurement in the first video stream; obtaining a second video stream at a second distance, larger than the first distance; using the first digital measurement and an angular measurement to an item appearing in the second video stream to determine a measurement of the second distance.