Cognex SurfaceFX Feature Extract Tool
Cognex’s SurfaceFX tool offers a new way to inspect physical features that are engraved, embossed, stamped, etc. It can find physical defects such as scratches, dents, puncture holes, etc. SurfaceFX outputs an image that any of Cognex’s existing tools can use to analyze. Cognex SurfaceFX opens up many possibilities for inspections that would otherwise be difficult or impossible. We have included some sample imagery below captured at KTM Research’s facilities to demonstrate the capabilities of SurfaceFX.
SurfaceFX Feature Extract Tool
The Cognex SurfaceFX capability are available on the In-Sight 7000 Gen II series of cameras. The feature is enabled by the new on-camera illuminator that offers individual control of four lighting quadrants. By capturing four separate images each illuminated by one quadrant of the illuminator, a reconstructed image similar to photometric stereo can be achieved. While not true photometric stereo, as available with MVTec Halcon’s photometric stereo feature, the Cognex SurfaceFX feature extract tool gives a similar effect with much less work.
Independently controlled quadrant illumination
While the new on-camera illuminator’s independent control of the four quadrants enables the SurfaceFX tool, it also opens up other new imaging possibilities that would have previously required complex off-camera hardware. Below is an example of a ping pong ball being imaged with each of the four lighting quadrants (left, top, bottom, right) demonstrating the directionality of the light.
The SurfaceFX tool takes these four images and generates the SurfaceFX image. The SurfaceFX image can then have any of the other Cognex filters, tools, or scripts applied. The new on-camera illuminator with independent quadrant control opens up many possibilities for novel inspection methodologies.
SurfaceFX Application Examples
The most direct and simple use of Cognex SurfaceFX is to find physical defects (bumps, holes, etc.) in a smooth surface. The example below shows a coffee creamer pouch with a small hole in the seal. With traditional illumination (left), this would very difficult for machine vision software to successfully identify. With Cognex SurfaceFX (right), the physical features, including the hole, are obvious while printed text/graphics practically vanish.
Below is an example of a foil packet with a lot code and expiration date stamped into the material. The shiny surface would normally make this inspection extremely difficult, even with off-camera lighting. SurfaceFX and the on-camera quadrant illumination make the stamped features stand out with enough contrast for simple inspection.
The example below is of an debossed lot code marking in an injection molded part. The original image (left) shows that with lighting setup to eliminate glare on the marking, low contrast makes the inspection very difficult. With SurfaceFX (right), the marking stands out in high contrast to the background and allows for easy OCR.
The examples above highlight features with sharp edges. Features with sharp edges work especially well with SurfaceFX but SurfaceFX can work equally as well with softer features. In the example below, the embossed information on the bottom of a coffee creamer is difficult to impossible to read (left) using machine vision. The SurfaceFX image (right) does an excellent job extracting the physical features with enough contrast for analysis.
The Solo cup lid below shows a difficult, but potentially possible text extraction application using diffuse lighting. This type of inspection is made significantly easier using SurfaceFX to increase contrast of the physical features. Like the coffee creamer example above, the lid has softer, rounded features, but SurfaceFX is still easily able to extract the features with sufficient contrast for analysis. Again, this example is using a stock In-Sight 7000 Gen II sensor with only the on-camera illumination.
One key area that Cognex SurfaceFX excels at with the on-camera lighting is imaging features on shiny or glossy surfaces. This was an almost impossible task before, but SurfaceFX easily extracts psychical features regardless of glare. The example below of a Leatherman tool would have been impossible with on-camera lighting without SurfaceFX.
In addition to imaging shiny surfaces, Cognex SurfaceFX can extract very fine details that would otherwise be impossible to discern. The vertical lines in this Taiwanese coin provide an excellent example of this capability. (Click for full size image.)
Coins provide an excellent example of everything Cognex SurfaceFX excels at. They are difficult to illuminate and have physical features that even with off-camera illumination are still difficult to analyze. Below we have included the full-resolution example of a newer United States penny.
Like the penny above, the quarter below also demonstrates SurfaceFX’s ability to extract physical features. In this example, all the text around the edge is debossed instead of embossed like is found on many coins.
Using Cognex SurfaceFX
In our opinion, the Cognex In-Sight 7000 Gen II is one of the best cameras that Cognex has produced to date. The on-camera illuminator is significantly better than anything that Cognex has released before. The fact that the new illuminator with independent quadrant control allows for the SurfaceFX tool is just one more reason to strongly consider this camera series for your next project.
There are some caveats to consider with SurfaceFX. The tool relies on illuminating the part from four different sides. The on-camera illuminator is larger than before, but will work best on objects smaller than three to four inches (75-100 mm). The camera also needs to be closer to the object than we are used to with Cognex’s other cameras, which can cause distortion issues.
For example, we can show you extreme detail in the back of the below penny. To the human eye, the Abraham Lincoln statue inside the Lincoln Memorial is almost invisible, but is easily extracted with SurfaceFX.
The image below of three pennies demonstrates the reduced field of view that is required to obtain the level of detail on this scale of the middle penny. Note that in this setup, the front face of the camera/lighting is approximately two inches (50 mm) from the coin. The image below shows the SurfaceFX effect dropping out on the neighboring pennies. Click the image for the uncropped full-resolution version.
The image of the three pennies above demonstrates an extreme example of the reduced usable field of view. In most applications, the FOV reduction will not be as extreme, but should be taken into account when designing a system using the new Cognex 7000 Series Gen II cameras.
If you have an application that you believe Cognex SurfaceFX would be a good solution for, feel free to contact KTM Research for more information, or to setup a demo. KTM Research specializes in machine vision and can make sure your vision project succeed.
About KTM Research
KTM Research is an engineering firm that specializes in industrial machine vision systems for quality control and vision-guided robotics. Formed in 2009, we are located in Tualatin, Oregon. We serve industries in the fields of advanced manufacturing, consumer electronics, bio-tech, food and beverage, research, and logistics. Our systems have been successfully used by customers across North America and Asia.
Our goal at KTM Research is to be the first call you make when faced with a vision challenge. Our team of engineers view themselves as an extension of your organization and strive to be your trusted vision partner. Our success is our clients’ success. Our collaborative approach to projects with our conservative and robust design process allows KTM Research to successfully complete projects that many others cannot.
Contact KTM Research at firstname.lastname@example.org for more information on our vision solutions.