Stripe Pattern Duty Cycle for Translucent Object Measurement
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Solution Overview
Problem
Existing methods for three-dimensional measurement of translucent objects, such as teeth, face challenges with poor measurement accuracy due to low signal amplitude and strong background signals from light penetration and backscattering, which are exacerbated by the use of contrast agents that can reduce accuracy if applied unevenly.
Innovation Solution
A method using a stripe pattern with a pulse duty factor less than 1 is projected onto the object, reducing disturbing background signals and enhancing measurement accuracy by increasing the signal amplitude, where the duty cycle is optimized by ensuring darker areas are wider than lighter areas, and phase-shift triangulation is employed to calculate height or intensity images from raw images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional sinusoidal stripe pattern with duty cycle equal to 1 is used, then the measurement process is simple, but the signal amplitude is low and background signals from light penetration and backscattering reduce measurement accuracy
Solution Approach 1:
The patent applies parameter changes by modifying the duty cycle of the stripe pattern from the conventional value of 1 to a value less than 1. This parameter change increases the signal amplitude and reduces the disturbing background signals from light penetration and backscattering, thereby improving measurement accuracy for translucent objects without requiring contrast agents
2Measurement precision
If the grating period is increased to reduce the disturbing effect of translucency, then the background signals are reduced, but the measurement accuracy decreases due to the principle involved
Solution Approach 1:
Instead of changing the grating period, the patent changes the duty cycle parameter of the stripe pattern. This alternative parameter change achieves the same goal of reducing background signals from translucency while maintaining measurement accuracy, avoiding the trade-off that would result from increasing the grating period
3Measurement precision
If a contrast agent is applied to increase signal amplitude, then the measurement accuracy improves, but the application process requires more effort and can reduce accuracy if applied unevenly
Solution Approach 1:
The patent makes the measurement system self-sufficient by using a modified stripe pattern (with duty cycle less than 1) that inherently compensates for the translucent properties of the object. This eliminates the need for external contrast agents and their application process, allowing the system to achieve high measurement accuracy without additional manual intervention or materials
Solution Approach 2:
The patent changes the stripe pattern parameters (duty cycle) to achieve the effect that contrast agents would provide, but without the need for their application. This parameter change in the projection system replaces the need for material application on the object surface
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 allows for higher measurement accuracy with a single raw image, reducing systematic errors and improving data quality without the need for contrast agents, especially in dental applications, by leveraging periodic stripe patterns with sinusoidal or Gaussian intensity distributions.
Implementation Method 1
projecting a stripe pattern whose pulse duty factor is less than 1 onto the recording object
Implementation Method 2
recording the projected stripe pattern as a raw image with a camera
Implementation Method 3
the principle of triangulation can be used, in which a projection device projects a single line of light or a stripe pattern of parallel lines onto the object to be recorded and the projected image under a parallax angle with an area camera again is recorded
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3a~3c
AI summary
A method for recording an image of an object includes projecting a strip pattern onto the object, recording the projected strip pattern as raw image data using a camera, and calculating an image of the object from the raw image data. A strip pattern having a duty cycle of less than 1 can be used to increase measuring precision during measurement of a translucent object, and can eliminate a need for additional contrast agents for a recording of the object.