Stereo Imaging for DPM Code Reading on Reflective Surfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for reading direct product marking (DPM) codes face challenges due to reflections and loss of color and physical characteristics, making it difficult to accurately identify DPM codes in high production rate environments, especially on reflective surfaces like metal parts and small objects such as pills.
Innovation Solution
An inspection system utilizing a stereo imaging device with linear cameras that captures high-resolution stereo image data, processes it in real-time to generate depth maps, and reduces reflection issues by using grayscale to represent relative distances, enabling reliable reading of DPM codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 2D imaging processes are used to read DPM codes, then the system is simple to operate, but reflections and loss of physical characteristics make accurate reading difficult
Solution Approach 1:
The patent transitions from conventional 2D imaging to 3D imaging by capturing depth information alongside intensity data. The stereo imaging system acquires images from multiple viewpoints and reconstructs three-dimensional surface geometry, enabling the system to differentiate between actual code features and reflection artifacts based on their spatial positions. This dimensional enhancement allows accurate DPM code reading on reflective surfaces while maintaining operational simplicity through automated processing.
2Productivity
If high production rate environments are used, then productivity increases, but imaging speed and quality specifications become harder to meet
Solution Approach 1:
The system implements continuous imaging and processing throughout the inspection process. Multiple cameras capture images continuously as objects move through the inspection zone, and the processing system continuously performs stereo matching and depth map generation without interruption. This continuous operation allows the system to maintain high imaging quality even at high production rates by ensuring every object receives complete inspection coverage during its brief passage through the system.
Solution Approach 2:
The system performs preliminary calibration and setup of the stereo camera geometry before production inspection begins. The baseline distance, camera orientations, and intrinsic parameters are pre-determined and stored for use during high-speed operation. This preliminary configuration enables the system to process images at high speeds without performing complex real-time calibration, thus maintaining both productivity and measurement precision.
3Reliability
If dot peen marking is used on metal parts, then permanent identification is achieved, but the reflective surface causes imaging difficulties
Solution Approach 1:
The stereo imaging system captures depth information that allows differentiation between the flat reflective metal surface and the three-dimensional dot peen markings. By reconstructing the surface geometry, the system can identify the raised or indented features of the DPM code regardless of surface reflectivity. The depth maps generated from stereo matching highlight the physical variations caused by dot peen marking, making code detection reliable on reflective surfaces where conventional 2D imaging fails.
4Measurement precision
If grayscale to depth conversion is implemented, then reflection problems are reduced, but processing complexity increases
Solution Approach 1:
The system replaces complex mechanical depth measurement devices with optical stereo imaging and computational algorithms. Instead of using physical probes or mechanical scanners to measure surface depth, the system uses pairs of cameras to capture images from slightly different angles and computationally reconstructs depth information through stereo matching algorithms. This substitution reduces mechanical complexity while achieving accurate depth measurements, and the processing is automated to minimize operational complexity.
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
The system effectively enhances the readability of DPM codes by reducing reflection problems and improving contrast, allowing for accurate identification and inspection of DPM codes on various surfaces, including metals and pills, in high-speed production environments.
Implementation Method 1
The use of the depth map reduces or eliminates reflection problems that may otherwise exist due to lighting of the DPM code on the object
Data Source
AI summary
A system and method of inspection may include capturing image data by a stereo imaging device. A determination as to whether noise indicative of a transparent or specular object exists in the image data may be made. A report that a transparent or specular object was captured in the image data may be made.