Full-field extraction of subtle displacement components via phase-projection wavelet denoising for vision-based vibration measurement

While vision-based methods are renowned for their ability in full-field vibration measurements, accurately and robustly extracting subtle displacements remains a significant challenge. To address this, this paper presents a novel Optimal Phase-projection Wavelet Denoising (OPWD) method for vision-based vibration measurement that is adept at extracting characteristics of subtle displacement components. The OPWD method enhances signal quality through a structured three-step process: constructing a signal model from pixel array data, transforming this model into the frequency-space domain, and applying wavelet denoising in the spatial dimension. The method was validated through experimental comparisons on a structural beam, confirming consistency with the resonance frequencies obtained from accelerometers and mode shapes from finite element analysis. This study also contributes a comprehensive framework that lays the groundwork for future developments and implementations of additional methods in vision-based vibration measurement.