As defined by the RAE, light is the physical agent that makes objects visible and our objective with artificial vision systems is nothing more than that, SEE. Locate parts and use that information appropriately to improve the operation of our facility.
An easy-to-understand example could be the location of a part on a conveyor belt. With a vision system we could calculate its position and transmit that information to a robot so that it can pick it up correctly.
Light must be used to adequately illuminate our scene. Lighting is the most important factor and its proper control is decisive for the final result. With this I do not mean that a lot of light is beneficial, but that its correct adjustment in our installation will be what marks the obtaining of good results.
Most of the time, in industrial environments the lighting conditions are not suitable. For this reason, it is chosen to artificially illuminate the work environment and even in some cases cabine the installation so that the external light interferes as little as possible in our application. What we are looking for is to have a constant and homogeneous light source at any time of the day. Changes in lighting can lead to false positives at the time of detection or even make it impossible to locate the parts.
We do not always seek to have great sharpness in all the details of our pieces. In certain applications it may be interesting to use widely known tools in the world of photography such as backlighting. With this technique, what is tried is to achieve a great contrast between our piece and the background of the image, thus obtaining a perfectly defined silhouette, which may be what interests us the most for our application. As Coco Chanel said “simplicity is the key to true elegance”.
However, despite its enormous importance, the selection of a good lighting system is often one of the most frequently neglected and undervalued parts of a vision system. Because as the saying goes “there is no worse blind than the one who does not want to see.”
Jaime Losada, PROBOTEC Technical Department.