Hybrid-driven structural modal shape visualization using subtle variations in high-speed video

Abstract

The phase-based motion magnification technique can exaggerate specific structural vibrations and obtain potential applications in visualizing and understanding modal shapes. However, the quality of motion magnification is affected by noise and clipping artifacts, especially in large amplifications. We propose a hybrid-driven motion magnification framework that combines Eulerian and Lagrangian motion processing. Since the structural global spatial vibration corresponding to different modal shapes usually accumulates energy differences in the timeline, from a Eulerian perspective, temporal intensity variations are denoised and separated according to the energy distribution to control spatial motions. Meanwhile, from a Lagrangian perspective, the motion magnification is realized by compensating spatial motion according to the magnified inter-frame motion vector field. By utilizing both Eulerian and Lagrangian motion processing, the proposed framework supports a larger amplification factor and achieves better performance in perceiving subtle vibrations in controlled modal tests.