There are various established technologies for inspecting parts. If users opt for industrial image processing, the question arises as to whether an inspection in 2D or 3D is advisable and what effort is involved in implementing the respective solution? Depending on the application, a proven 2D system is often the first choice - even if the (theoretical) advantages of 3D image processing may be obvious.

There are two reasons for this: Firstly, until now there was no 3D vision system that met the requirements of most inspection applications in terms of ease of use and cost. Three-dimensional vision inspection was simply too expensive and complicated for most companies, and there were few vision tools that worked with true 3D images. This meant that an additional PC had to be installed to actually solve the application. The consequences were increased space requirements and increased programming effort.

On the other hand, 2D inspection with a smart camera was usually robust enough and very user-friendly. Ergo, in many cases there is or was no real need to make the costly and difficult transition to a 3D inspection system.

Blue laser optics

When inspecting weld seams on rubber hoses, the 'In-Sight 3D-L4000' detects even the smallest defects and can take precise measurements.

© Cognex

With the introduction of the 'In-Sight 3D-L4000' embedded vision system from Cognex, this is set to change. This smart camera enables engineers to solve a range of in-line inspection, guidance and measurement applications on automated production lines quickly, accurately and cost-effectively thanks to a comprehensive suite of true 3D vision tools that are as easy to use as Cognex's industry-proven 2D vision tools thanks to the 'In-Sight' spreadsheet environment. Another industry first is the patented speckle-free blue laser optics.

Normally, 3D vision systems struggle with speckle
- light effects that occur when the laser light is scattered from the surface of the inspected part back to the vision system. Speckle is a problem in existing 3D vision systems as it changes the appearance of the part and reduces image accuracy. The system can only estimate where the laser is located.

The 'In-Sight 3D L-4000' uses a new, patented laser in the blue light range that delivers speckle-free images at a resolution of 2K. The imager sees a clear laser line, which increases the accuracy of the 3D images and thus significantly contributes to the quality and repeatability of the measurement and inspection results. The system also provides its own illumination for both 3D and 2D images, meaning it does not require an external light source.

Intelligent processing

With most 'traditional' laser-based 3D vision systems, the laser head captures an image that is sent to a PC for processing. This reliance on PC programming makes 3D inspection cost-effective only for very complex applications. The Cognex 3D system, on the other hand, has its processing power built right in. This allows the vision tools to perform true 3D point cloud inspections without the need for an external controller or third-party PC-based software. Another positive side effect: thanks to the on-board processing, the images can be analyzed in the shortest possible time.

In the past, visual 3D inspection was difficult to understand and use.

© Cognex

Most existing systems convert 3D data into 2D images. The height of a point is displayed as a gray value. This means that a false color representation of the rasterized 3D image in the 2D image is used to understand the height information. In such a representation, it is difficult to see and successfully process the nuances of the 3D part. It is common practice to convert a section of the rasterized 2D image into a 1D height profile.

With the technology used in the '3D-L4000', however, the image is a pure point cloud - a real 3D image is seen and evaluated, not a reduction to a 1D height profile.

Operate without programming knowledge

Janina Guptill is Senior Marketing Communications Specialist at Cognex Germany in Karlsruhe.

© Cognex

'In-Sight 3D-L4000' uses the intuitive In-Sight spreadsheet development interface to quickly and easily set up and run 3D applications, without programming or external processing. It also allows 2D and 3D vision tools to be combined in the same application, resulting in faster implementations, and streamlines factory integration with a complete I/O and communication feature set.

The 3D system includes all the 3D measurement tools traditionally expected of a 3D vision system, for example for plane and height determination. In addition, it has a comprehensive set of 3D vision tools such as PatMax3D, Blob3D, 3D Geometry, specifically designed for inspections in a real 3D space. This makes it easier to measure and locate parts or irregularities on the surface as well as gaps, edges and angles - even on parts with complex geometry such as pistons or hinges.