3D Measurement Using Non-Crossing Line Projection
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Solution Overview
Problem
Existing methods for 3D measurements of objects using structured backlighting face high error rates due to mechanical oscillations and complexity, particularly when dealing with objects having varying reflective properties and deep recesses, leading to inaccurate determination of linear dimensions and prolonged measurement times.
Innovation Solution
A method utilizing a portable projection unit and cameras in a single housing, projecting a known image with non-crossing lines at different triangulation angles to simplify and automate the measurement process, with subpixel determination algorithms to accurately calculate longitudinal and vertical coordinates, reducing errors and measurement duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single camera records the distorted image of structured backlighting, then the device complexity is reduced, but the measurement precision deteriorates due to inability to resolve ambiguities in gaps and low spectral reflectance areas
Solution Approach 1:
The patent combines multiple cameras (at least two cameras positioned at different locations) to record the distorted image of structured backlighting simultaneously. This merging of multiple detection devices resolves the technical contradiction by maintaining high measurement precision through multi-angle observation while keeping the device complexity manageable through integrated simultaneous recording
2Productivity
If mechanical oscillations occur during measurement, then the measurement time is reduced, but the measurement precision deteriorates due to errors in position determination
Solution Approach 1:
The patent performs preliminary calibration by establishing correspondence between camera coordinates and object coordinates before actual measurement. This preliminary action creates a reference framework that allows rapid subsequent measurements to maintain high precision even when mechanical oscillations occur during the measurement process itself
Solution Approach 2:
The patent uses the recorded distorted images to calculate actual coordinates through coordinate transformation based on the established correspondence. This feedback mechanism continuously corrects for mechanical oscillations by comparing observed positions against the calibrated reference, maintaining measurement precision despite speed increases
3Measurement precision
If multiple periodic distributions of light intensity are projected alternately, then the measurement precision is improved through phase distribution analysis, but the measurement time increases significantly
Solution Approach 1:
The patent projects at least one periodic distribution of light intensity (such as sinusoidal patterns) onto the object surface. This periodic action enables precise measurement through phase analysis of the distorted patterns, achieving high measurement precision while controlling measurement time through optimized projection sequences
Solution Approach 2:
The patent performs preliminary calibration to establish coordinate correspondence before actual measurement. This preliminary action reduces the time required during actual measurement by pre-configuring the measurement framework, allowing rapid processing of periodic light distributions without sacrificing precision
4Adaptability or versatility
If the projection unit and cameras are in separate housings, then the adaptability is improved, but the reliability deteriorates due to mechanical oscillations affecting relative positions
Solution Approach 1:
The patent integrates the projection unit and cameras into a single housing, merging these components into one rigid structure. This eliminates relative position changes between components during measurement, ensuring high reliability by preventing mechanical oscillation errors while maintaining adaptability through the overall system design
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 significantly simplifies and automates the measurement process, nearly eliminates errors caused by mechanical oscillations, and reduces measurement time by using multiple cameras at varying triangulation angles to enhance accuracy and precision in determining 3D object dimensions.
Implementation Method 1
projecting on the surface of the controlled object a beam of light, characterized by modulated spatial intensity
Implementation Method 2
registering of the image of the probing backlight pattern distorted by the topography of the controlled object's surface
Implementation Method 3
determining the height of the controlled object's surface topography with a digital electronic computer measuring the topographic height based on the distortion value of the probing backlighting pattern
Data Source
AI summary
A method of 3D measurement is performed using a first camera and a second camera located at different distances from the projector. The method includes projecting a known projection pattern that includes at least two non-crossing lines to form a first band and a second band on a surface of an object. The method includes recording first and second images of the object using the first and second cameras, respectively. The method includes determining a first longitudinal coordinate of a first point within the first band and a first vertical coordinate of the first point within the first band; determining a second longitudinal coordinate of the first point within the first band; and determining a second vertical coordinate of the first point within the first band. The method includes determining a final vertical coordinate of the first point by comparing the first longitudinal coordinate to the second longitudinal coordinate.