Inspection Apparatus Using Characteristic Size Parameter for 3D Shape Measurement
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Solution Overview
Problem
Existing photometric stereo inspection systems face challenges in accurately measuring three-dimensional shapes of workpieces due to strict installation requirements and limitations in image processing parameters, which hinders their application in fine uneven flaw inspection and OCR of inscribed characters.
Innovation Solution
An inspection apparatus that includes an illumination section, an imaging section, a computing section for calculating normal vectors, and a determination section, which uses a characteristic size parameter to facilitate the generation of inspection images by performing accumulation computing on pixel values based on normal vectors and reduced images, thereby simplifying the setting of image processing parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photometric stereo principle is used for accurate three-dimensional shape measurement, then measurement precision is improved, but device complexity and installation requirements increase
Solution Approach 1:
The system automatically acquires scale information from the inspection target image itself and performs self-calibration without requiring external calibration objects or manual parameter input. The illumination and camera are integrated into a single inspection apparatus that autonomously determines its own geometric parameters
Solution Approach 2:
The illumination device and camera are merged into a single integrated inspection apparatus, eliminating the need for separate calibration of independent components and simplifying the installation configuration while maintaining photometric stereo measurement capability
2Adaptability or versatility
If normal vector image or reflectance image is used for inspection, then inspection capability is improved for certain applications, but user burden increases due to multiple image processing parameter adjustments
Solution Approach 1:
The system automatically determines the optimal inspection image type and processing parameters based on the characteristics of the inspection target, eliminating the need for users to manually adjust multiple image processing parameters. The apparatus self-adapts to different inspection scenarios
Solution Approach 2:
The inspection apparatus generates multiple types of inspection images (normal vector image, reflectance image, and other derived images) through a unified system that automatically selects the appropriate processing mode, providing versatile inspection capability across different applications without requiring separate processing pipelines
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 solution allows for easier parameter setting in generating inspection images, improving inspection accuracy and reducing user burden, particularly in applications like fine uneven flaw inspection and OCR, by selecting a suitable characteristic size based on the inspection tool.
Implementation Method 1
an imaging section for receiving reflective light from the illuminated inspection target to generate a luminance image in accordance with the photometric stereo method
Data Source
AI summary
A photometric processing part calculates a normal vector of a surface of a workpiece from a plurality of luminance images acquired by a camera in accordance with the photometric stereo method, and performs synthesis processing of synthesizing at least two images out of an inclination image made up of pixel values based on the normal vector calculated from the plurality of luminance images and at least one reduced image of the inclination image, to generate an inspection image showing a surface shape of the inspection target. In particular, a characteristic size setting part sets a characteristic size which is a parameter for giving weight to a component of a reduced image at the time of performing the synthesis processing. The photometric processing part can generate a different inspection image in accordance with the set characteristic size.