Semi-Spherical Calibration Assembly for 3D Light-Camera Positioning
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Solution Overview
Problem
Inspection cameras face challenges in accurately detecting defects on products due to inadequate lighting and difficulty in determining the relative 3D positions between the camera and light sources, especially in environments with varying surface materials and conditions.
Innovation Solution
A semi-spherical calibration object assembly is used to determine the relative 3D positions of light sources by capturing reflections from multiple semi-spherical reflective objects, allowing for precise calibration of the lighting apparatus and camera setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single light source is used, then the lighting apparatus is simple, but the light quality is inadequate for capturing images of diverse surface materials
Solution Approach 1:
The lighting apparatus is divided into multiple independent light sources (first light source, second light source, etc.) that can be individually controlled. Each light source can be activated selectively based on the surface characteristics of the product being inspected, allowing optimization of lighting conditions for different materials (reflective, transparent, opaque surfaces) without requiring a completely different lighting system for each case.
Solution Approach 2:
The lighting apparatus incorporates a controller that dynamically adjusts which light sources are activated based on real-time requirements. The system can switch between different lighting configurations and sequences to maximize flexibility and adapt to various products, components, materials, and environments, transforming a static single-light system into a dynamic multi-light system.
2Adaptability or versatility
If the camera is positioned separately from the light sources, then the inspection system has flexible positioning, but the relative 3D position between camera and light sources becomes difficult to determine
Solution Approach 1:
A calibration object assembly serving as an intermediary element is introduced into the system. This assembly contains multiple calibration objects with known geometric features that are visible to both the camera and light sources. By capturing images of these calibration objects under known lighting conditions, the system can calculate and determine the relative 3D positions between the camera and each light source, enabling precise spatial relationships to be established despite the separate positioning of camera and lights.
3Measurement precision
If multiple calibration objects are used, then the calibration accuracy is improved, but the calibration process becomes more complex
Solution Approach 1:
The calibration object assembly serves multiple functions simultaneously: it provides known geometric features for spatial calibration, acts as a reference object for determining light source positions, and enables verification of camera positioning. By using a single integrated calibration assembly with multiple calibration objects rather than separate calibration procedures for each parameter, the system achieves comprehensive calibration while managing complexity through consolidation.
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 defect detection by ensuring optimal lighting conditions and precise positioning, enhancing the capability of inspection cameras to capture high-quality images of diverse products.
Implementation Method 1
capturing reflections from multiple semi-spherical reflective objects
Data Source
AI summary
In an example embodiment, rather than a single calibration object, a plurality of calibration objects are placed within the field of view of an inspection camera at the same time. Each of the calibration objects is or includes a semi-spherical reflective object having known sizes. During a calibration process, the distance between a light source and camera may be determined by activating the light source and capturing an image of how the light source bounces off each of the calibration objects, and more particularly the location on each of the calibration objects that the light source appears to reflect from. This allows the angle that the light source strikes each calibration object to be calculated, and these angles can then be used to determine the distance between the light source and the camera.