3D Shape Measurement Using Segmented Grating and Stereo Fusion
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Solution Overview
Problem
Conventional three-dimensional shape measurement apparatuses struggle to measure smooth surfaces without texture, as they rely on geometric structures based on texture information, limiting their ability to accurately determine the shape of measurement targets.
Innovation Solution
A three-dimensional shape measurement apparatus utilizing a combination of optical triangulation and stereo methods, where grating pattern light is obliquely illuminated and captured from multiple directions, using the grating pattern as texture information when surface texture is unclear, and employing plane images for height data production above a reference height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical triangulation method is used to measure three-dimensional shape, then measurement precision is improved, but the measurable height is restricted by the grating pitch
Solution Approach 1:
The measurement system is segmented into multiple imaging optical systems, each with different grating pitches. The first imaging optical system uses a first grating pitch for low-height measurements, while the second imaging optical system uses a second grating pitch for high-height measurements. This segmentation allows the system to overcome the height limitation of a single grating pitch by dividing the measurement range into multiple segments.
Solution Approach 2:
The patent introduces a new dimension to the measurement capability by adding a second imaging optical system with a different grating pitch. This dimensional expansion in terms of measurement range allows the system to measure both low and high heights effectively, transforming the single-dimension limitation into a multi-dimensional capability.
2Adaptability or versatility
If the stereo method is used to measure three-dimensional shape, then measurable height range is extended, but the method becomes unavailable for smooth surfaces without texture
Solution Approach 1:
The patent merges the optical triangulation method and the stereo method into a single integrated measurement system. The optical triangulation component (using grating patterns) provides reliable measurements for smooth surfaces, while the stereo component (using texture information) extends the measurable height range. By combining these two methods, the system achieves both reliability on smooth surfaces and extended height capability.
Solution Approach 2:
The measurement system is designed with multi-functionality to handle both textured and smooth surfaces across various height ranges. The first and second imaging optical systems can selectively operate based on the measurement requirements, making the system universally applicable to different surface types and height conditions.
3Adaptability or versatility
If multiple imaging optical systems with different grating pitches are used, then measurable height range is extended, but device complexity increases
Solution Approach 1:
Each imaging optical system is optimized with specific local quality characteristics - the first system is optimized for low-height measurements with its grating pitch, while the second system is optimized for high-height measurements with its different grating pitch. This local optimization allows each subsystem to perform its specific function efficiently, reducing the overall complexity compared to a single universal system.
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 and precise three-dimensional shape measurement of both textured and smooth surfaces by integrating optical triangulation and stereo methods, extending the range of measurable heights and maintaining accuracy at low heights.
Implementation Method 1
The main image-capturing parts obtain a grating pattern image of the measurement target by receiving reflection light of the grating pattern light that is illuminated from the main pattern illumination parts to the measurement target and obliquely reflected by the measurement target
Implementation Method 2
The plurality of main image-capturing parts obtain a plane image of the measurement target by receiving reflection light of the light that is illuminated from the illumination part to the measurement target and reflected by the measurement target
Data Source
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AI summary
A three-dimensional shape measurement apparatus includes a plurality of main pattern illumination parts, a plurality of main image-capturing parts and a control part. The main pattern illumination parts obliquely illuminate grating pattern light in different directions toward a measurement target. The main image-capturing parts obtain a grating pattern image of the measurement target by receiving reflection light of the grating pattern light that is illuminated from the main pattern illumination parts to the measurement target and obliquely reflected by the measurement target. The control part produces height data of the measurement target by using grating pattern images of the measurement target, or produces height data of the measurement target by using image positions of plane images for the measurement target and texture information of the measurement target. The control part employs a grating pattern illuminated on the measurement target as the texture information to produce height data of the measurement target. Thus, a three-dimensional shape may be measured more easily and accurately.