3D Profile Reconstruction Using Color Gratings and Picture-in-Picture
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Solution Overview
Problem
Traditional automatic metrology technologies face challenges with identification of single-color gratings on rough surfaces, shadow interference, and inability to adjust grating density and contrast, leading to inaccurate three-dimensional profile reconstruction, and require complex equipment setups with separate displays for viewing and adjusting images.
Innovation Solution
A measurement method using subpixel localization with color gratings and picture-in-picture switching on a single display, featuring a projection apparatus emitting grating light with identical contrast, a photographic apparatus for image extraction, and a central processing unit for image analysis and adjustment, allowing for precise three-dimensional profile reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-color gratings are projected on rough surfaces, then the measurement can be performed, but the grating stripes twist and deform making identification difficult
Solution Approach 1:
The patent applies color changes by projecting color gratings instead of single-color gratings. The color grating includes multiple color regions (red, green, blue, cyan, magenta, yellow, white, and black stripes) that enhance the contrast and identifiability of grating stripes on rough surfaces. The color differentiation allows the measurement system to distinguish between adjacent stripes more easily, preventing misidentification even when stripes twist or deform due to surface roughness.
2Measurement precision
If grey-scale grating is projected for measurement, then the measurement can be performed, but background light and shadow cause erroneous stripe judgment
Solution Approach 1:
The patent uses color gratings with distinct color regions to overcome the harmful effects of background light and shadow. The multiple colors (red, green, blue, cyan, magenta, yellow, white, and black) provide strong visual contrast that maintains stripe identifiability under varying lighting conditions. The color differentiation allows the system to distinguish grating stripes from shadows and background variations, preventing erroneous stripe judgment.
3Adaptability or versatility
If fixed gratings are used, then the system is simple, but the stripe density and contrast cannot be adjusted for different workpieces
Solution Approach 1:
The patent applies dynamics by making the grating parameters adjustable rather than fixed. The system includes an adjustment module that can dynamically change the stripe density and contrast of the projected gratings according to different measurement requirements and workpiece characteristics. This dynamic adjustment capability allows the same system to adapt to various workpiece sizes, surface conditions, and measurement precision requirements without requiring multiple fixed grating sets.
4Ease of operation
If two separate displays are used for grating projection and image extraction, then the functions are separated, but the equipment becomes complex and difficult to operate
Solution Approach 1:
The patent applies merging by combining the grating projection display and the extracted grating image display into a single display device. The display shows both the projected grating pattern and the captured image with extracted features simultaneously, allowing operators to perform both viewing and adjustment functions on one screen. This integration simplifies the equipment setup, reduces the number of components, and makes the system easier to operate while maintaining all necessary functional capabilities.
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 three-dimensional profile reconstruction with improved identification of gratings on rough surfaces, adjustable grating density and contrast, and streamlined equipment operation with direct adjustment capabilities on a single display, enhancing measurement precision and efficiency.
Implementation Method 1
a projection apparatus, used for emitting grating light towards a workpiece under measurement, the grating light having a plurality of grating stripes with identical contrast, and the grating light forming a grating image of stripes comprising a plurality of colors on the workpiece under measurement
Implementation Method 2
a photographic apparatus, used for extracting the grating image from the workpiece under measurement
Data Source
AI summary
The present invention is a measurement method of three-dimensional profiles and a reconstruction system thereof using subpixel localization with color gratings and picture-in-picture switching on a single display, wherein the measurement method includes: 1. Preparation step; 2. Projection step; 3. Image extraction step; 4. Image fine-tuning step; 5. Image processing step; and 6. Reconstruction step. The system includes: a projection apparatus, emitting a grating towards a workpiece under measurement, and forming a grating image on the workpiece under measurement, the contrast values of the plurality of grating stripes of the grating image being identical; a central processing unit, using the grating image and picture-in-picture of a display thereof to fine tune and reconstruct three-dimensional profiles of the workpiece under measurement. Thereby, the grating stripes have equal contrast for easier identification; the display has switchable picture-in-picture; and an adjustment module can adjust the grating.