3D Measuring Apparatus Using Tensor Hypersurface Calibration
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Solution Overview
Problem
Conventional three-dimensional shape measurement techniques, such as the light section method and fringe pattern projection, face challenges including system errors, calibration complexities, and limitations in measurement accuracy due to mechanical moving mechanisms, lens distortion, and the need for precise calibration, which hinder efficient and accurate measurement processes.
Innovation Solution
A measuring apparatus that projects a grating fringe pattern and uses a camera to capture images, generating data tuples that include coordinates, light intensity, and height information, which are converted into phase angles to construct a tensor product type composite hypersurface, allowing for accurate calibration and measurement by reducing systematic errors and lens distortion effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light section method or fringe pattern projection is used for three-dimensional measurement, then non-contact measurement capability is achieved, but systematic errors and calibration complexities arise
Solution Approach 1:
The patent replaces complex mechanical calibration mechanisms with a computational approach. By using a computer to automatically calculate calibration parameters from captured images and apply correction algorithms, the system eliminates the need for manual mechanical adjustment and complex physical calibration fixtures, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent transforms the calibration process by changing from fixed mechanical parameters to variable computational parameters. The system captures images at multiple positions and uses computer algorithms to dynamically calculate and adjust calibration parameters, allowing flexible adaptation without physical reconfiguration and simplifying the overall calibration system.
2Area of stationary object
If mechanical moving mechanisms are used in the light section method, then measurement range scanning is achieved, but measurement time increases and efficiency decreases
Solution Approach 1:
The patent replaces mechanical moving mechanisms with a stationary optical system combined with computational methods. Multiple cameras or a single camera with multiple positions capture images simultaneously or in rapid succession, and a computer processes these images to reconstruct the three-dimensional shape, eliminating mechanical movement bottlenecks and significantly improving measurement efficiency.
Solution Approach 2:
The system uses periodic illumination patterns (such as projecting fringe patterns or light sections at different phases) to encode three-dimensional information. By capturing multiple images with periodic variations in the projected pattern and processing them computationally, the system achieves complete surface scanning without mechanical movement, thereby improving productivity.
3Measurement precision
If precise calibration is performed to reduce systematic errors, then measurement accuracy improves, but calibration time and labor increase
Solution Approach 1:
The patent implements self-calibration functionality where the system automatically captures calibration images and computes calibration parameters without requiring external manual intervention. The computer processing unit automatically performs the calibration calculations and stores the parameters, enabling the system to calibrate itself quickly and accurately, thereby reducing both calibration time and labor while maintaining high measurement accuracy.
Solution Approach 2:
The system performs preliminary calibration by capturing images of a calibration object at multiple predetermined positions before actual measurement. These preliminary images are processed to pre-calculate calibration parameters that are then stored and applied during subsequent measurements, eliminating the need for time-consuming on-site calibration and allowing rapid deployment.
4Ease of manufacture
If lens distortion is present in the camera system, then image capture is simplified, but measurement accuracy deteriorates
Solution Approach 1:
The patent addresses lens distortion by introducing distortion parameters as variables in the imaging model. The system captures images at multiple positions and uses computer algorithms to calculate distortion parameters, then applies correction transformations to the captured images. This approach maintains the simplicity of the camera hardware while computationally compensating for distortion effects, thereby preserving measurement accuracy without complicating the manufacturing.
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 enables quick and easy calibration, ensures horizontality and flatness in measurements, and reduces the impact of lens distortion, thereby improving measurement accuracy and efficiency in three-dimensional shape determination.
Implementation Method 1
a projector (1) that projects a grating fringe; a camera (4) that photographs an image
Implementation Method 2
a converter that converts the light intensity to a phase angle of the projected fringe pattern
Data Source
AI summary
A measuring apparatus of this invention comprises: a projector; a camera; a generator that generates, from a photographed image of a fringe pattern projected by the projector at a time of calibration onto each of surfaces, first tuples, each including coordinates of a point on a light receiving plane (LRP) of the camera, light intensity of the point and the height of the surface; a converter that converts the light intensity to a phase angle of the projected fringe pattern (PFP), and generates second tuples, each including the coordinates of the point on the LRP, the phase angle and the height of the surface; a hypersurface generator that generates data representing a tensor product type composite hypersurface (TPTCH) from data of the second tuples; an extractor that extracts data of third tuples, each including coordinates of a point on the LRP and light intensity from a photographed image of a fringe pattern projected by the projector at a time of measurement onto an object to be measured; a second converter that converts the light intensity to a phase angle of the PFP to generate data of fourth tuples, each including the coordinates of the point on the LRP and the phase angle; and an interpolator that carries out interpolation by using the data representing the TPTCH to generate height data corresponding to the data of the fourth tuple.