3D VISION
Lessons when working in 3D
We ask four experts to give their advice for 3D imaging best practices
How do you decide if you can benefit from 3D vision, especially on a limited budget? Inder Kohli, Teledyne Dalsa: ‘3D vision helps solve several inspection challenges that are difficult, if not impossible, to be handled by 1D or 2D imaging techniques. For example, variation in height, defects caused by indentation or bubbling of laminate, measuring object thickness, coplanarity of adjoining surfaces [and] uniformity or asymmetry of extruded parts. ‘Historically, it required specialist
knowledge to build and maintain 3D systems using discrete parts. In expert hands, this might yield the desired performance, but over time field support might erode profits. So, customers can benefit from factory- calibrated, fully integrated 3D profile sensors, like Teledyne’s Z-Trak2. When selecting a 3D profiler, users must consider not only the cost of the unit, but also software tools, deployment time and, equally important, in-field service.’ Fredrik Nilsson, Sick IVP: ‘For tasks that
involve measuring dimensional features, it is very likely that 3D imaging will be the more cost efficient choice in the end. It will provide reliable measurement even if the parts to inspect are presented at different positions in the field of view. In addition, segmentation of the parts from the background is greatly simplified by using 3D vision, where the contrast issues in greyscale or colour imaging is avoided. Pricing for 3D vision solutions is constantly decreasing, and taking the complete solution cost into account from the beginning – including the maintenance – the choice for 3D may even save you money in the long run.’
Electronics quality checks made using laser triangulation
What factors should be defined to be successful? Nilsson: ‘Te first thing to consider is if your application has static or moving parts and how accurately you need to measure them. Te answer to this has a big impact on the choice of 3D technology and also to the solution cost. Other topics to consider are what height range and width you need to cover, ambient conditions (that is, interfering sunlight or other light sources, vibrations, available space), surface properties of your parts (for example, very shiny, very matt) and what variety of parts can be expected.’ Yoann Lochardet, Teledyne e2v listed other parameters important for choosing
24 IMAGING AND MACHINE VISION EUROPE AUGUST/SEPTEMBER 2021
a 3D technology to suit the application: ‘Distance range (minimum and maximum); field-of-view; resolution; response time or frame rate; power consumption; lighting budget; compactness of the system; dynamics of the objects of interest (slow- or fast-moving targets); and hardware and software cost and complexity. ‘Time-of-flight is a good choice for a
maximum distance of more than 1 to 2m, with moderate requirements on precision and accuracy, and is very efficient in managing uncontrolled ambient setups and with moderate to high speeds. For instance, it is a good choice for machine vision applications (distance ranges up to
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