A promising new 3D vision system now makes it easy to inspect 3D parts as with a 2D smart camera. While 3D optical inspection used to require a lot of programming but offered few benefits, Cognex's new technology brings better image quality, simplified application development and a wide range of 3D inspection tools - greatly expanding the range of applications in industrial automation.
When it comes to inspecting parts, users can choose from several established technologies. If the decision is made in favour of the industrial vision, the question arises: do you need a 2D or 3D inspection and what efforts are needed to implement the corresponding solution? Depending on the application, a proven 2D system is often the first choice, although the (theoretical) benefits of 3D image processing may be obvious.
There are two reasons for this. The first is that until now, there was no 3D vision system that met the ease-of-use and cost requirements of most inspection applications. Three-dimensional vision inspection was simply too expensive and complicated for most companies, and there were also few vision tools that worked with real 3D images. This required the installation of an additional PC to solve the application, which required much more space and programming. The second reason: 2D inspection with a smart camera works very reliably and with great ease of use. Therefore, in many cases, there is or was no real need to make the costly and difficult transition to a 3D inspection system.
New possibilities for automatic 3D inspection
This situation is changing with the introduction of industrial vision specialist Cognex's In-Sight® 3D-L4000 vision system. This one-of-a-kind smart camera enables engineers to quickly, accurately and cheaply solve a range of online inspection, guidance and measurement applications on automated production lines. It offers a complete suite of true 3D vision tools that are as easy to use as Cognex's industry-proven 2D vision tools, thanks to the familiar and robust environment of the In-Sight spreadsheathy. In addition, patented blue laser optics without reflections are a first in the industry, allowing the capture of high quality 3D images.
Blue laser optics make the difference
Users of 3D image processing are probably familiar with this: in general, 3D imaging systems are confronted with reflections—the light effects that occur when laser light is diffused from the surface of the room to the imaging system. Reflection is a problem in existing 3D vision systems because it changes the appearance of the room and reduces the accuracy of the image. The system can only estimate the location of the laser. To date, no 3D system has been able to eliminate these reflections and thus produce images good enough to perform reliable 3D inspection applications.
However, the type of laser used in the In-Sight 3D-L4000 is an important technical advance in laser imaging - and explains the excellent results achieved. The 3D-L4000 eliminates reflections by using a special laser in the blue light range. The imager therefore sees a clear laser line, which allows for more accurate 3D images. In addition, the laser provides its own lighting for 3D and 2D images - the system requires no outside light.
Intelligent processing on real-world images of 3D dot clouds
In most "traditional" 3D vision systems based on the laser, the laser head captures an image that is sent to a PC for processing. At the same time, they offer a limited selection of tools, most of which can only be used for a simple height measurement. The dependence of PC programming only makes 3D inspections cost-effective for very complex applications. The In-Sight 3D-L4000, on the other hand, has built-in processing power. This allows vision tools to perform real 3D point cloud inspections without the need for an external controller or third-party PC software. An interesting secondary advantage is that with integrated processing, image analysis can be done in a very short time.
In the past, 3D visual inspection was difficult to understand and use. Most existing systems turn 3D data into 2D images. In doing so, the height of a point is represented by a gray value. To understand the height information, we use a false-color representation of the 3D image framed in the 2D image. In this representation, it is very difficult to see and successfully process the nuances of the 3D part. A common method is to convert part of the framed 2D image into a 1D height profile. However, with the new technology used in the 3D-L4000, the image is a pure cloud of dots; What you see and evaluate is a true 3D image, not a reduction to a 1D height profile. And because 3D inspection is new to most users, 3D tools are designed so that everyone can fully understand and use the new three-dimensional tools. In other words, you do essentially the same thing, but unlike before, you're working on an image that looks exactly like the room itself.
Intuitive configuration with advanced 3D inspection tools - without programming skills
Another novelty of the In-Sight 3D-L4000 is the use of the Intuitive Development Interface In-Sight Spreadsheet to quickly and easily set up and execute 3D applications without the need for programming or external processing. It simplifies application development and streamlines factory integration with a comprehensive set of I/S and communications functions. It also combines 2D and 3D vision tools in one application, speeding up deployments.
The In-Sight 3D-L4000 includes all the traditional 3D measurement tools expected from a 3D vision system, such as determining planes and heights. In addition, it features a comprehensive set of 3D vision tools such as PatMax3D, Blob3D, 3D Geometry and many others, designed from the start for inspections in a real 3D space. This allows for easy measurement or identification of surface parts or irregularities, as well as gaps, edges and angles, even for parts with complex geometry such as pistons or hinges.
A wide range of applications
The technical advances and the easy-to-use features of the new 3D-L4000 make it an ideal tool for a wide range of applications in many sectors, including agri-food, consumer products, packaging, automotive, medical devices and electronics. Its great ease of use and the fact that no external PCs, and therefore no programming skills, are required for configuration and processing ultimately make laser-based 3D imaging a viable and affordable option. Automation engineers now have a real choice between 2D and 3D.
Auteur : Janina Guptill, Senior Marketing Communications Specialist, Cognex Germany Inc.
Read more: cognex.com
