{"id":10102721,"date":"2021-09-23T16:06:07","date_gmt":"2021-09-23T21:06:07","guid":{"rendered":"https:\/\/www.erbessd-instruments.com\/?page_id=10102721"},"modified":"2025-06-04T15:40:58","modified_gmt":"2025-06-04T20:40:58","slug":"looking-glass-technique","status":"publish","type":"page","link":"https:\/\/www.erbessd-instruments.com\/de\/looking-glass-technique\/","title":{"rendered":"The Looking Glass Technique – See the invisible"},"content":{"rendered":"\t\t
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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\"looking-glass-technique-for-vibration-analysis\"\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The Looking Glass Technique \u2013 See the Invisible<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Incredible as it may seem, the vibration (or at least a large part of it) can be detected through video recording with incredible resolution. Saving a huge number of hours in studies that before were time consuming if not impossible to do.<\/p>

Inspired by the EC-135 Airborne Command and Control Aircraft that served as the United Nations strategic airborne launch control and command center during the cold war Optical Vibration has created the Looking Glass Technique within DragonVision\u00ae<\/span><\/span><\/strong>\u00a0to differentiate it from common techniques.<\/p>

So, what is the vibration tracking? And better yet, what is it for?<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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What is the Looking Glass Technique?<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The Looking Glass technique is the optical vibration method used to obtain meaningful vibration signals from a video recording combined with a unique and trusted calibration method that utilizes a traditional accelerometer signal. It is a vibration analysis method that uses our unique micro motion tracking algorithm in video files. In fact, it is used today to detect and measure vibrations of thousands of points simultaneously with only one video recording.<\/p>

The results of this type of vibration analysis depend on the quality of the recording. Likewise, the maximum frequency visible in the spectra is related to the number of frames per second that have been taken.\u00a0<\/span><\/strong><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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How can Looking Glass Technique Help Me?<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Video vibration tracking allows users to measure thousands of points at the same time which, otherwise, would be either impossible to measure or they would consume a lot of time with conventional methods. In this way, it gives you the possibility to analyze structures, movement, deflection and phase much more precisely and with very little effort. At the same time, this technique allows users to export amplified vibration simulations that are very easy to interpret even for people who are not experts in vibrational analysis.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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How Does the Looking Glass Technique Work?<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The smallest movement that this method can detect is much smaller than the pixel size of a conventional camera. So how does it work?<\/p>

The principle of this method is based on the fact that, in a conventional camera, before an object moves from one pixel to another, it creates a small color change in the next pixel. In fact the color from both pixels change progressively until the object occupies entirely the next pixel sensor.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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This method measures the changes in angularity and changes in the amount of color from each pixels (in fact from an entire area of pixels). First, the software identifies color patterns within small user defined areas. These patterns must have changes in angularity and color differences in order to distinguish it from the rest of the patterns. The target areas are found automatically by the software and the user can only modify some quality parameters and surface.<\/p>

Second, for each video frame, the software will identify the average color changes on the targeted points and its corresponding area. Thus, being able to track small changes in each frame with great accuracy.<\/p>

Finally, all that information obtained is translated into vibration signals like an FFT, phase, or time wave form for analytical purposes.<\/p>

Learn more about DragonVision\u00ae<\/span><\/span><\/strong><\/a><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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(Image 1: Tracking vibration points at 3550 RPM)<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Reliability in Amplitude<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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To obtain reliable vibration values, it is essential to have a calibration system. All cameras have different types of lenses, as well as resolutions, not to mention that the zoom used and the distance at which the video is taken can change the appreciation of the movement.<\/p>

Therefore, the system needs a comparative calibration to achieve reliability. The best method to calibrate these signals is using an accelerometer.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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There are 2 comparative methods used to calibrate these type of signals:<\/p>

By RMS value<\/strong>: this method requires a single point on the machine to be measured with a conventional vibrometer. The software will then calibrate the movement according to the RMS value of that point.<\/p>

By cross channel<\/strong>: this method is the most accurate and requires a complete recording of the vibration signal for the software to process it in the form of a spectrum (FFT). Using this method the software will be able to calibrate each frequency individually eliminating false frequencies that could be generated by the aliasing effect.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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\n\t\t\t\t\t\tWiSER 3x\t\t\t\t\t\t<\/h3>\n\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\tWireless Triaxial Accelerometer\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t
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