High-speed camera measurements are increasingly being used in modal analysis to instantaneously measure full-field structural responses by extracting the displacement information from images using digital-image-correlation and other optical-flow methods. High-speed cameras capable of filming full frame at high frame rates can be very expensive and produce image resolutions of only approximately 1~mega pixel, which is why this research aims at measuring and identifying the full-field response using cheaper, still-frame cameras with a higher image and intensity resolution, such as digital single-lens reflex (DSLR) and mirrorless cameras.
Using spectral optical flow imaging (SOFI) full-field operational shapes can be acquired using still-frame cameras. This study demonstrates the hybrid modal-parameter identification of full-field mode shapes using an accelerometer and a DSLR camera for responses far above the DSLR camera's frame rate (demonstrated up to 1~kHz).
See also a related paper/video: [Measuring full-field displacement spectral components using photographs taken with a DSLR camera via an analogue Fourier integral], [Short VIDEO presentation of the principles].
Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
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