Assessment of displacement measurement performance using phase-based optical flow with the HalfOctave pyramid

The effectiveness of the Complex Steerable Pyramid (CSP) in enhancing subtle structural motions for dynamic facility observation is widely acknowledged. However, further analysis and evaluation are needed to determine the applicability of directly utilizing CSP for displacement measurement in engineering applications. This paper assesses the displacement measurement performance of phase-based optical flow (PBOF) using HalfOctave CSP. Initially, the impact of the CSP's down-sampling rates on the accuracy of displacement measurements in PBOF is assessed by simulating motion to identify suitable configurations. Afterwards, the accuracy of this method is investigated within the effective range of displacement measurement by simulating motion. The results of the simulation experiments indicate that the optimal down-sampling factor for CSP should be set to zero. When CSP is at its optimal down-sampling factor and using filters located in the middle of the effective filter level, PBOF achieves the best comprehensive displacement measurement performance.