Sunday, July 22, 2012

Intriguing lighting configuration

A marketing email from camera-maker AVT included a link to German machine vision integrator Ziemann & Urban, so I followed the advice of Yogi Berra, (“When you come to a fork in the road, take it,) and clicked through to their website.

Good move, if I do say so myself. They have a ton of interesting application stories and videos to read and watch – clearly they know machine vision – but one I found especially interesting related to wheel inspection.

I’m not going to share the whole story – you’ll need to click through to “Automatic adjustment of wheel rims” for that – but I do want to share the photos of the lighting set up. (I don’t own the copyright but I’m hoping that Z&U will appreciate the free publicity I’m giving them.)

Now wheels are complicated things to image. They tend to be reflective and they have lots of complex geometry. I’ve seen massive cloudy day illuminators used for this kind of task but they tend to have a huge footprint. So let’s look at Z&U’s approach.

This first picture shows the camera surrounded by an array of linear LED lights. Separating the lights are aluminum baffles. I have to wonder if the baffles help create a kind of cloudy day effect.

The next picture shows the LED’s powered up. Interesting effect, don’t you think?

I’m not sure I can explain what’s going on, but if you look at the screen shots on Z&U’s website, it seems to work.

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