Vision Correction Aid System for Head and Eye Tracking
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Solution Overview
Problem
Current systems for optimizing ophthalmic lenses, particularly multifocal lenses, are inadequate in accurately determining a person's habitual eye movements and head movements during tasks like reading, which are crucial for designing lenses with optimal vision correction features.
Innovation Solution
A system comprising a camera, display device, wearable accessory with visual reference marks, and image analysis means to track the position and orientation of the head and eyes relative to visual targets, allowing for the calculation of head and eye movement distribution during tasks, thereby informing lens design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera and image analysis system are used to track head position and orientation, then measurement precision of eye movement habits is improved, but device complexity increases
Solution Approach 1:
The patent introduces an accessory worn on the person's head as an intermediary carrier for visual reference marks. This accessory serves as a mediator between the tracking system and the person's head movements, allowing precise measurement of head position and orientation without requiring direct complex instrumentation on the head itself. The accessory simplifies the overall system by providing a stable platform for reference marks that can be easily tracked by the camera.
Solution Approach 2:
The system uses visual reference marks (copies or representations) attached to the accessory to represent the actual head position and orientation. Instead of directly measuring complex head movements, the system tracks the two-dimensional projection of these reference marks in the camera image plane, which serves as a simplified copy that contains all necessary information for reconstruction of three-dimensional head pose through image analysis algorithms.
2Reliability
If visual reference marks are used to determine head position, then reliability of eye movement data is improved, but ease of operation deteriorates
Solution Approach 1:
The accessory with visual reference marks serves itself by automatically providing the tracking information needed. The reference marks are designed to be naturally detectable by the camera system, and their positions automatically update as the head moves, eliminating the need for manual calibration or adjustment during operation. The system self-calibrates by detecting the known geometric relationships between the reference marks.
3Measurement precision
If the system tracks both head and eye movements separately, then measurement precision of eye movement habits is improved, but device complexity increases
Solution Approach 1:
The patent combines the measurement of head position and eye movements into a single integrated system. The accessory tracks head position while the camera simultaneously captures eye position through image analysis. By merging these measurements and processing them together through image analysis, the system achieves precise determination of eye movement habits relative to head movement without requiring separate complex measurement systems for each parameter.
Data Source
AI summary
The invention relates to a system that is used to aid in determining vision correction. The inventive system is characterised in that it combines: a camera which can take animated images of the subject's face along a determined visual axis; a display device which represents the images taken by the camera; an accessory which can be worn by the subject in a fixed manner on the head and which bears a plurality of visual reference marks; means which form the visual reference mark(s) and which can cover at least two determined regions in relation to the camera; and image-analysis means which can analyze the position of the visual reference marks in the images taken by the camera and deduce therefrom the position and spatial orientation of the accessory and, consequently, the subject's head when the subject is looking at a visual target, in order to ascertain information relating to the visual behaviour of the subject when the subject moves the direction in which he/she is looking.