In 2017, the seminar theatre devoted to 3D imaging at UKIVA’s Machine Vision Conference and Exhibition was the best attended of the event.
This year’s event, which took place in May, has once again had a complete theatre dedicated to this topic. There is no doubt that 3D imaging is continuing to grow in popularity, as technology improves and prices drop.
A change of emphasis
3D imaging has been available for many years, but only comparatively recently have the dramatic improvements in processor capabilities made it possible to carry out the complex computation of 3D images in real-time for production line deployment. These improvements in processing power, coupled with the emergence of high performance CMOS sensors, has allowed the development of easy-to-use 3D systems at price points now comparable to some 2D imaging systems. In addition, such systems are capable of making highly sophisticated measurements. Less than 5 years ago, 2D imaging was the natural choice for machine vision and the decision on whether to use 3D systems was based on whether the application really needed it in order to justify the cost. However, now, while 2D imaging is still an optimal tool in many applications, better performance and lower costs mean that businesses can look at 3D as an additive process to 2D rather than an either/or equation. This brings the advantages of 3D without sacrificing the benefits of 2D. The two most popular inline 3D inspection technologies are laser triangulation and stereo vision with structured light (fringe projection). These both offer non-contact scanning of parts and generate the high-resolution 3D scans required for feature measurement and verification.
3D vs 2D imaging
Whilst 2D vision systems are capable of a wide range of inspections, they do not support measurement related to 3D shape, making it difficult to measure critical features such as object flatness, surface angles, or volumes of the target component. 3D laser profiling and structured light methods allow decisions to be made on product shape, proportions and even surface quality (indentations scratches, dents etc). 2D sensors utilise an object’s contrast (edge data), which means 2D relies heavily on lighting and colour/greyscale variation to detect features for measurement. However, 3D is contrast invariant, making it ideal for inspecting low contrast objects and it is also immune to minor lighting variation or ambient light. The use of 3D matching tools enables 3D models to be compared to a known 3D or ‘golden’ template for product verification. Both 2D and 3D inline inspection processes include scanning, measurement, and control—all performed in a highly optimized pipeline of operations to keep up with factory speeds.
3D in action
3D inspection has applications in industries as diverse as food & beverage, pharmaceutical, automotive, packaging, electronics, transport, logistics and many more. From checking pizza, cakes and biscuits for shape, size, edge defects and thickness, to making gap and flush measurements on automotive panels, or measuring the size, shape and position of holes in sheet metal components, or detecting shape defects in pharmaceutical tablets, or checking the rims of containers for surface defects before applying foil lids, the list goes on and on. 3D imaging is playing an increasingly important role in manufacturing and processing.