The choice between 2D and 3D vision systems for inspection and measurement can be a tough one to navigate. Both 2D and 3D vision systems offer unique advantages and are suited to different types of inspection tasks. Let’s break down the details to help you know when to opt for one over the other.
2D Vision Systems: When to Use Them
Simple Shape and Pattern Recognition: 2D vision systems are ideal for inspections involving simple shape recognition, pattern matching, and barcode reading. They excel in environments where the object's surface (2D) features or graphics are the primary focus.
Controlled Lighting Conditions: These systems work best in controlled lighting conditions since they rely on contrast differences in the image. Lighting design is an important factor when considering 2D vision systems, and often we will use external lighting and blackout enclosures to ensure consistent image quality for the camera’s tools to measure. Even though AI/machine learning helps with inconsistent lighting, having consistent lighting makes the application more robust, even when AI is used.
High-Speed Applications: 2D vision systems are typically faster than 3D systems and are more suitable for high-speed production lines. Speed will depend on the number of tools applied to the images and complexity of the task.
Cost-Effectiveness: For tasks that don’t require depth information, 2D vision is often the more cost-effective solution.
Good questions that will typically lead to 2D vision system solutions:
Can you see the defect or measurement easily with your eyes?
Does the defect have a high contrast?
Do you have high-speed requirements for the application (i.e., <300 ms per full part inspection)?
Examples of 2D Cameras we use: Cognex In-Sight 3800 or D900; Keyence CV-X or XG Series
3D Vision Systems: When to Use Them
Complex Geometries and Volume Measurements: When the inspection task involves understanding the shape, size, and volume of objects in detail, 3D vision systems are more appropriate. These systems deliver crucial depth information, ensuring precise measurements. For example, for applications like bin picking systems, 3D measurements are critical to ensure the picking is accurate and repeatable.
Varying Object Heights or Depths: In cases where objects have varying heights or depths during inspection, 3D vision can provide more accurate inspections that automatically adapt and fixture to the part. Compared to 2D systems where varying heights can cause image blurriness (due to focal length change) or skew of the image, 3D systems handle varying heights well.
Challenging Lighting and Surface Conditions: 3D vision is less affected by lighting variations and can handle surfaces with low contrast or reflective properties better than 2D systems. Often a pattern will be projected onto the surface during the scanning process to reduce reflections and get an accurate measurement of the surface. This can lead to simpler vision tools that don’t require as much calibration as 2D systems often need.
Good questions that will typically lead to 3D vision system solutions:
Is the part highly reflective or low contrast?
Do you need high-accuracy depth information?
Is the part tough to light accurately across the different recipes?
Examples of 3D sensors we use: LMI Gocator 2000/3000 series; Keyence RB Bin-Picking system or LJ 3D laser profiler.
Real-world Implementations
2D Vision in Action: Label Application Verification
The customer needed to measure the angle of labels applied to a product and ensure that the right labels were applied correctly to three sides of the product. Using three Keyence CA-H500CX 2D cameras, we image each side of the product as it passes through a blackout enclosure, check for label presence and angle, and then reject the product if it falls outside of the recipe criteria.
3D Vision in Action: Post-Height Measurement
The customer needed to replace plunger dial indicators to measure the height of a post on their product. Using a LMI Gocator 3210 sensor, we scan the product on the conveyor, anchor our tools dynamically to the object, and isolate the area to measure and find the distance between the tallest part of the top of the post and an average of the height around the base of the post.
Conclusion: Balancing Needs and Capabilities
The choice between 2D and 3D vision for quality inspection should be based on the specific requirements of the task at hand. Understanding the strengths and limitations of each system is key to making an informed decision. In some cases, a combination of both might be the best solution, offering the advantages of both depth perception and high-speed inspection capabilities.
This article aims to provide a general guide for professionals in the field of industrial automation. Need help choosing the right sensor for your application? Reach out to us, We can help guide you and your team.