Contactless 3D Ear Canal Scanning via Optical Motion Sensing
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Solution Overview
Problem
Current methods for obtaining three-dimensional shape data of tubular bodies, such as the external ear canal, are invasive and prone to errors due to the use of impression materials, which can distort the shape and rely on skilled personnel, while contactless measurement techniques are mainly used for outer shapes, not inner tubular structures.
Innovation Solution
A method and system that generate three-dimensional shape data by using a movable image capturing device with an objective optical system and motion sensor to capture images and space information, converting this data into three-dimensional shape data without physical contact, by calculating movement loci, setting cylindrical coordinates, and determining the existence and intensity of reflected light from infinitesimal surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impression material is injected into the external ear canal to obtain ear impression, then data regarding the inner shape of the external ear canal can be collected, but the skin moves due to the injected material causing the ear impression to differ from the original shape
Solution Approach 1:
The patent replaces the mechanical impression material injection system with an optical measurement system. A camera captures images of the ear canal interior while a motion sensor tracks the camera's position and orientation. This optical-mechanical substitution eliminates the need for physical contact that causes skin distortion, thereby improving measurement accuracy without the harmful effects of material injection.
2Measurement precision
If impression material is used to make ear impression, then the inner shape data can be obtained, but the hardened material cannot be taken out when the curvature of the external ear canal is sharp
Solution Approach 1:
The patent substitutes the mechanical impression material process with a contactless optical scanning system. The camera and motion sensor system captures three-dimensional shape data by taking multiple images from different positions inside the ear canal and reconstructing the 3D model computationally. This eliminates the removal difficulty entirely since no physical material is injected or hardened inside the ear canal.
3Measurement precision
If impression material is injected into the external ear canal, then ear impression can be formed, but the accuracy depends on the skill of the person making the impression causing variability
Solution Approach 1:
The patent replaces the skill-dependent manual impression-making process with an automated optical scanning system. The camera systematically captures images while the motion sensor automatically tracks position and orientation. A computer algorithm then processes these images to generate the three-dimensional shape data, eliminating human skill variability and making the process objective and repeatable.
4Object-affected harmful factors
If contactless measurement technique is used, then outer shape can be measured without contact, but the technique is not suitable for measuring the inner shape of tubular bodies
Solution Approach 1:
The patent applies the nesting principle by placing the camera inside the tubular structure (ear canal) to capture images of the inner surface. The motion sensor is integrated with the camera system, and both are positioned within the confined space of the ear canal. This nested configuration enables contactless measurement of internal tubular surfaces, extending the applicability of contactless techniques to previously inaccessible geometries.
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
Enables accurate, contactless acquisition and reproduction of the inner shape of tubular bodies, reducing errors associated with impression materials and skill variability, and applicable to various tubular structures like ear canals, digestive tracts, and tubing products.
Implementation Method 1
receiving space information on the image capturing device upon image capturing by the image capturing device based on a signal from a motion sensor
Implementation Method 2
determining whether or not reflected light from the infinitesimal surfaces can enter each light receiving element of the image capturing element
Data Source
AI summary
A three-dimensional shape data production method and a system for the same for realizing contactless receiving of data regarding the inner shape of a tubular body which includes a step of generating multiple pieces of two-dimensional image data based on a signal from an image capturing device configured to be movable inside a tubular body and configured to capture an image of the inside of the tubular body; a step of receiving space information on the image capturing device upon image capturing by the image capturing device based on a signal from a motion sensor placed at the image capturing device; and a step of associating the two-dimensional image data and the space information with each other and generating three-dimensional shape data of the inside of the tubular body based on the two-dimensional image data and the space information.