Thursday, June 18, 2015

Why GenICam 3.0 deserves your attention

Some engineers love standards. They get all excited about reading them, and positively orgasmic when offered the chance to be on a standards committee.

Me, I’m not so interested. I get that standards are important, and I understand that my work is much easier as a result of machine vision standards like GenICam, but I can’t get excited about them. However, a press release from the European Machine Vision Association (EMVA) regarding the new GenICam 3.0 was quite interesting. Subtitled, “3D machine vision made easy,” this explains how EMVA has standardized interfaces for 3D cameras in the same way as 2D cameras have been standardized for some years.

This is good news. As vision engineers have been waking up to the possibilities of 3D – and I confess to being a big fan – we need the cameras to be as close to ‘plug-and-play’ as possible.

Also in the new release, some enhanced point-cloud capabilities. Learn more by reading the press release.

Tuesday, June 16, 2015

Job for a rule-loving engineer?

As an engineer you don't have much of a career path, unless you want to go into management. (I advise against it.) So as a way of recognizing professional seniority and competence the role of Principal Engineer was created.

In this context, “Principal” implies head or most senior. Every so often though, I see jobs advertised for “Principle Engineer”. “Principle” has an entirely different meaning. A principle is a rule or fundamental doctrine. So I assume a Principle Engineer creates rules. I imagine they could be machine vision rules, in which case he or she would be a Machine Vision Principle Engineer, but this doesn't sound like the kind of work a senior or highly experienced machine vision specialist would be engaged in.

What's the takeaway? If you should be writing a job description for a highly experienced machine vision specialist, title it “Principal Engineer” and I might apply. I am not however interested in being a “Principle Engineer.”

Sunday, June 14, 2015

Machine vision education

Every so often a reader finds my blog while trying to teach themselves about machine vision. Then I get a very nice email, (I love getting emails – it shows you actually read my rambling thoughts,) asking where they can find good educational material.

It’s difficult. There are textbooks, like Nello Zeuch’s “Understanding and Applying Machine Vision,” but they go out of date quickly. (Yes, I know the Laws of Physics are pretty much immutable, but vision technology evolves constantly.) The alternative is online material.

Of course, you can’t trust everything you find on the web, but I have to think MIT Open Courseware is pretty high quality. So you might want to take their “Machine Vision” class. This dates from 2004, so it’s not exactly bang up to date, and looking at the syllabus, it does seem to assume some prior knowledge of the subject.

I haven’t taken the class myself, yet. If I can break away from blogging I might give it a go. In the meantime, if any of you readers out there want to send me a review I’ll be happy to share your thoughts with the vision world.

Tuesday, June 9, 2015

Sometimes you just have to vent

On occasion developing a machine vision application can be frustrating. Scope creep is one issue, when the customer throws a new defect type at you during the final run-off and says, “If it can’t find this I’m not paying for it.” Then there are the more technical problems, like dealing with batch-to-batch shade variation, or the irritating niggles of configuring IP addresses for GigE cameras. (I’m going out on a limb here and hoping that you deal with all this too.) So every now and then I feel the need to vent.

What I didn’t realize though is that venting can improve the way your hardware performs.

I bet you’re surprised by that too but it must be true. Why else would Gore, (yes, the people who make GORE TEX® fabrics, run a webcast called, “Enhancing Sensor Reliability Through Venting”?

I learned about this from an email. I couldn’t find anything on their website ( although I’m sure Google will find it. If you want to know how venting helps, that is.

Thursday, June 4, 2015

Camera interface standards

It's my impression that the machine vision industry has pretty much standardized on one interface. It’s GigE for area or matrix cameras, leaving USB3 to the scientific/medical community and falling back on CameraLink for linescan applications. (Though I notice Dalsa now has a family of GigE linescan cameras.) However, I know other industries like other formats.

So, when I saw a post on the excellent Adimec blog asking, “Which digital video interface is best for global security systems?” I didn’t expect to learn much. But there were a couple of interesting snippets.

First, regarding GigE, “Processing required to pack and unpack video generates additional heat and uncertain latency…” Now that is news to me. Yes I have noticed a couple of my favorite GigE cameras seem to run very hot, but I hadn’t compared them with USB3 equivalents. Now I think I will.

Second, someone seems to have a bit of a downer on USB3:

  • Large connector and interface driver
  • Maximum throughput unpredictable (chipset, PC motherboard and driver dependent)
  • Sustainable speed is much lower than theoretical limit
  • Unreliable operation with longer cables (>3 m)”

Interesting points. There’s been so much hype over USB3 that the downsides seem to have been forgotten. Good to see Adimex removing the rose-tinted specs.

This is why it’s important to keep reading the machine vision blogs. You never know quite what you’ll learn. (And kudos to Adimec for providing consistently good content.)

Sunday, May 31, 2015

Should we hold a caption contest?

The big Automate show has come and gone, but it lives on forever online. As you may know, Vision Systems Design magazine presented awards for special achievement in the machine vision realm at the show. What you may not know is that there is a slideshow of these presentations on the website.

Now I’m not a talented photographer, so I shouldn’t criticize, but I won’t let that hold me back. And perhaps the photographer was elbowed out of the prime position, and perhaps he/she had some serious lag between pressing the button and the image being acquired, but seriously, these are some amateur photos.

On the other hand, some are really rather funny. Like the one of Andy Wilson pushing his glasses back up his nose. (Now you want to look, so here’s the link:\)

So I think we should have a caption contest. Let’s see who can come up with the most amusing speech bubbles. Send me an edited/marked up screen shot and I just may publish the one that’s most amusing (after getting permission from Andy of course!)

And sincere congratulations to those award recipients. Well done! I shall be looking closely at your products and services in the weeks ahead.

Tuesday, May 26, 2015

When you’re backlighting cylindrical parts

I see backlighting used all the time in machine vision training classes and at trade shows, typically for gauging or locating shapes. Look closely though and you’ll see the targets are flat objects – boxes, stamped parts – those kinds of things. Never machined steel shafts.

There’s a good reason for that. Unless you’re using a collimated backlight you won’t get a true image. That’s because the backlight emits light over 180 degrees, and some of those rays strike the target shaft and reflect in to the camera, as shown in this rather crude sketch.

This means you will see bright pixels in what should be dark areas of the image, and those can play havoc with your vision tools.

Interestingly, I observed this in a recent application note from National Instruments. “Developing a High-Speed, High-Accuracy Measuring System for Automotive Screw Inspection” includes some screenshots from the system. If you look closely at image 3 in the gallery you’ll see what I mean.

Now there are ways around this. The best is to use collimated light (where all the rays travel in the same direction,) but if you can’t do that use the smallest backlight possible and position it as far behind the target as possible. That way you’ll cut down on those tangential rays coming off the part and into the camera.

There is no charge for this snippet of advice. All I ask is that you keep coming back. If you’d like to link to this page, even better.