Foot Measurement Using Diffractive Light Patterns
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Solution Overview
Problem
Existing foot measurement methods are cumbersome, time-consuming, and prone to inaccuracy due to complex devices, manual data entry, and sensitivity to lighting conditions, often requiring the foot to remain still and bare, which can be uncomfortable and limiting in terms of applicability.
Innovation Solution
An apparatus and method using a camera and diffractive optical elements to project and photograph patterns of light onto the foot, allowing for accurate measurement of foot characteristics like length, width, and arch height, regardless of footwear, with adjustable light sources and reflective elements to enhance data capture and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 3D modeling of the entire foot is performed, then comprehensive foot shape information is obtained, but device complexity and measurement time increase significantly
Solution Approach 1:
The patent segments the foot measurement into two distinct components: 2D sole plane measurement and 3D arch height measurement. The 2D sole is captured using a simple overhead camera system, while the 3D arch information is obtained separately through lateral photography with a ruler reference. This segmentation allows comprehensive foot characterization without requiring complex full 3D scanning equipment.
Solution Approach 2:
The patent transitions from attempting full 3D modeling to a hybrid approach: capturing the 2D sole plane from above and adding the third dimension (arch height) through a separate lateral measurement. This dimensionality change strategy uses simple 2D photography combined with reference objects to infer 3D characteristics, avoiding the need for complex volumetric scanning systems.
2Ease of manufacture
If mechanical measurement methods are used, then implementation is simple, but information about foot shape cannot be provided
Solution Approach 1:
The patent replaces traditional mechanical measurement tools (rulers, calipers, physical molds) with optical photography systems. Digital images captured from above and from the side, combined with image processing algorithms, substitute for manual mechanical measurements. This substitution maintains simplicity while enabling comprehensive shape information extraction through digital analysis of photographed features.
3Measurement precision
If laser scanning is used, then size and shape can be determined, but the device is complicated and scanning takes time
Solution Approach 1:
The patent uses periodic flashing light sources to illuminate the foot during photography. The flash duration is controlled to be shorter than the maximum allowable movement distance divided by foot movement speed, effectively freezing foot motion during capture. This periodic illumination enables single-shot photography that captures the entire foot position instantaneously, eliminating the time-consuming sequential scanning process.
Solution Approach 2:
The patent replaces the moving laser source or detector mechanism with a stationary camera system that captures the entire foot in a single photograph. This substitution eliminates the mechanical movement components and sequential measurement process, reducing measurement time while maintaining precision through digital image analysis.
4Measurement precision
If the foot must remain still during measurement, then measurement accuracy is maintained, but the measurement process becomes time-consuming and uncomfortable
Solution Approach 1:
The patent employs periodic flashing light with duration shorter than the foot movement threshold to capture the foot position instantaneously. This allows the foot to move naturally during the measurement process while still obtaining a sharp, accurate image at the moment of flashing, eliminating the need for the foot to remain still throughout an extended measurement period.
Solution Approach 2:
The patent performs preliminary calibration by photographing a ruler or reference object before or during the foot measurement. This preliminary action establishes the scale and coordinate system, allowing the foot dimensions to be extracted directly from the photograph without requiring the foot to be held in a fixed position for extended calibration procedures.
5Measurement precision
If special lighting conditions and textures are required, then foot outline detection is improved, but device complexity and operational constraints increase
Solution Approach 1:
The patent uses periodic flashing light with variable duration as a controllable parameter to freeze foot motion. By adjusting the flash duration to be shorter than the foot movement distance divided by movement speed, the system achieves sharp images of moving feet without requiring special lighting setups or textured backgrounds, maintaining operational convenience while improving 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 simplifies the measurement process, reduces the impact of ambient light, and allows for accurate analysis of foot characteristics, enabling quick and comfortable measurement of both bare and socked feet, improving the speed and accuracy of foot data analysis for shoe and insole selection.
Implementation Method 1
at least one optical element arranged to be placed in the line of propagation of a beam of light produced by the at least one light source for spreading out the beam of light into a set of patterns of light
Data Source
Figure 1~2a
Figure 2b~3a
Figure 3b~3c
AI summary
The invention pertains to an apparatus for producing measurement data of a foot (220, 220a, 220b). The apparatus comprises at least one light source (110, 110a, 110b); at least one optical element (120, 120a, 120b) arranged to be placed in the line of propagation of a beam of light (130, 130a, 130b) produced by the at least one light source (110, 110a, 110b) for spreading out the beam of light (130, 130a, 130b) into a set of patterns of light (140, 140a, 140b) so that the patterns of light (140, 140a, 140b) are projected directly from the optical element at least partly on the sole of the foot (220, 220a, 220b) placed for photography; and a camera (230) for photographing directly the patterns of light (140, 140a, 140b) which are projected on at least the sole of the foot (220, 220a, 220b) placed for photography and which follow the shapes of the sole of the foot. In addition, the invention relates to a method for producing measurement data of a foot (220, 220a, 220b) and a system for analyzing a foot (220, 220a, 220b).