Evaluation Engineering - December 2008 - (Page 39)

application stories. Even if the problem addressed isn’t exactly the same as yours, the information still can be useful. Prosilica, PPT Vision, Matrox Imaging, and Cognex are a few of the companies that regularly publish this kind of free material. Training programs are offered by many suppliers, sometimes conducted at your company and sometimes online. A few introductory courses are free, but generally you have to pay for training. Speciﬁc questions or problems can be dealt with by technical support engineers. Websites always give an e-mail address and sometimes a phone number for technical support. In addition, many sites list frequently asked questions and answers. Interactive design tools present a vendor’s products from the user’s point of view. Lens selection programs are a good example. In many of these, you are required to enter approximate dimensions for the ﬁeld of view, working distance, and the smallest dimension that must be imaged. The number of camera pixels and the size of the sensor also affect lens choice. However, it’s very easy to enter values for which no lens is suitable, and selection programs that return “no lens found” are of little help. Instead, a few selection guides return the closest match. This is a great help to the novice machine vision developer who needs to become familiar with the interactions among the many parameters. For example, if you wanted to capture an image of a 1 m x 1 m object but with only a 100-mm working distance, a very large angle of view is implied. The closest match in this case might be a lens that required a 5-m working distance. Immediately, you can see that this is the speciﬁcation causing a problem. It’s a matter of perspective—no pun intended. A product-speciﬁc selection matrix focuses on the available products, and you simply need to choose among them. In contrast, an interactive selection program that shows you the closest match is focused on your application: Tell us what you need to do, and we’ll see how close we can come to satisfying the requirements. In addition, because choices often are not independent, you need to understand the limitations implied by the rest of the vision system. For example, a major beneﬁt of GigE Vision™ cameras is that a separate frame grabber isn’t required. Instead, camera data is transferred via gigabit Ethernet directly to the host PC. While this is an economical approach, it requires host processor bandwidth that may not be available. And, the performance of a real-time vision system can be affected by both the Windows operating system and a standard Ethernet network interface card (NIC). Continued on page 40 since 1996 Visit www.rsleads.com/812ee-022 www. ev alua t ion e n gin e e rin g.com December 2008 • EE • 39 http://www.rsleads.com/812ee-022 http://www.rsleads.com/812ee-022 http://www.evaluationengineering.com

Table of Contents Feed for the Digital Edition of Evaluation Engineering - December 2008

Evaluation Engineering - December 2008 Contents Editorial Product Briefing Test Software C-V Measurements Nanoelectronics Test Product Guide Company Guide Machine Vision EMC Test Index of Advertisers

Evaluation Engineering - December 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.