Spectacle Fitting Depth Detection Using 3D Structured Light
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining parameters for spectacle fitting, such as those described in U.S. Pat. No. 7,740,355 B2, face inaccuracies due to incorrect positioning of the person and difficulties in finding corresponding points under varying lighting conditions, which affects the accuracy of dimension determination for spectacle lens centration.
Innovation Solution
A method and device that utilize depth information detection, including a light field camera or time-of-flight sensors, to determine distances between the head and the device, allowing for accurate positioning compensation and improved parameter determination by creating a 3D model of the head, which can be used to virtually fit spectacles and determine centration parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stereo image data and 3D model calculation are used to determine spectacle fitting parameters, then the determination of centration parameters is enabled, but inaccuracies occur due to incorrect positioning of the person and difficulty in finding corresponding points under varying lighting conditions
Solution Approach 1:
The patent transitions from 2D image-based measurement to 3D structured light scanning. By projecting a known 3D pattern onto the face and capturing the deformed pattern from multiple camera angles, the system obtains reliable 3D coordinates of facial features regardless of lighting conditions or head position. This dimensional transition resolves the contradiction by making measurements robust against the previously problematic 2D image variations.
Solution Approach 2:
The system changes the measurement parameter from 2D image intensity (which varies with lighting) to 3D spatial coordinates obtained through structured light triangulation. By using the known geometry of the projected pattern and the triangulation principle, the system derives accurate 3D positions that are independent of illumination conditions, thereby resolving the reliability issue while maintaining measurement precision.
2Measurement precision
If a pair of image recording units are used to generate stereo image data, then three-dimensional model calculation is possible, but the device complexity increases and requires finding corresponding points in image pairs
Solution Approach 1:
Instead of using complex stereo vision algorithms to find corresponding points between two images, the patent projects a known 3D pattern (a copy of the reference geometry) onto the face. The cameras then capture the deformed pattern, and by comparing the captured pattern with the known reference pattern, the system directly computes 3D coordinates without needing to match corresponding points between multiple images. This copying approach simplifies the device and processing while maintaining measurement precision.
3Productivity
If the person is positioned in front of the device for image recording, then spectacle fitting parameters can be determined, but positioning inaccuracies lead to deviations from the desired setpoint position
Solution Approach 1:
The patent employs real-time 3D scanning and dynamic head position detection. The system continuously captures the 3D geometry of the face and the position of the head relative to the device. By dynamically calculating the head position from the 3D coordinates and comparing it with the desired setpoint position, the system can compensate for positioning inaccuracies and determine accurate spectacle fitting parameters even when the person is not perfectly positioned. This dynamic approach maintains both productivity and measurement precision.
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 the accuracy of spectacle fitting parameters by compensating for positional deviations and improving the determination of centration parameters, enabling more precise fitting of spectacles regardless of head position, thus ensuring correct lens placement and optimal fit.
Implementation Method 1
A method and device that utilize depth information detection, including a light field camera or time-of-flight sensors, to determine distances between the head and the device
Implementation Method 2
A method and device that utilize depth information detection, including a light field camera or time-of-flight sensors
Data Source
AI summary
A depth information detection device detects an item of depth information relating to a user's head, including a distance from the user's head to the device. On the basis of this depth information and, if applicable, additional information such as images, an evaluation device determines the desired parameters for fitting the spectacles, such as centering parameters.