Background <p>Vision-based measurement methods are nowadays widely used in structural tests due to their non-contact nature and full-field measurement capability. Typically, out-of-plane motion measurements require two or more cameras to compensate the depth information, with the additional cameras and synchronization systems increasing the overall cost.</p> Objective <p>To propose an efficient monocular vision method for measuring the full-field out-of-plane displacement of plate structures.</p> Methods <p>The image area of interest is first discretized into finite elements, and a full-field warp function is built by interpolating the out-of-plane nodal displacements using finite element shape functions. Subsequently, the parametric homography is combined with the finite element-based warp function to relate image motion to out-of-plane displacement. The nodal displacements are then determined by matching the deformed and un-deformed image regions within the digital image correlation (DIC) framework.</p> Results <p>Numerical simulations confirm that the measurement error remains at a low level under appropriate element size and camera configurations. Experimental validation on the out-of-plane vibration of a steel plate further demonstrates a close agreement with the laser vibrometer results in both displacement and mode frequency/shape measurements.</p> Conclusions <p>The proposed monocular method enables cost-effective measurement of full-field out-of-plane displacement, demonstrating its potential as a practical tool for out-of-plane vibration analysis and modal identification of plate structures.</p>