Informed pixel pushing: A new method of large-motion handling for phase-based optical flow

In this paper, a novel method is presented to increase the efficacy of phase-based optical flow (PBOF) in cases of simultaneous relevant super-pixel and sub-pixel motions. To date, PBOF performs well for sub-pixel motions of interest while measurement potential for super-pixel motion remains limited. Although current methods exist across the literature to handle irrelevant super-pixel motions otherwise obstructing sub-pixel extraction, they are typically aimed at removing the super-pixel motion. The proposed method does not assume irrelevancy, instead working to maintain the entire motion signal without resolution reduction or combined processing techniques. The objective of this work is to reframe the small motion assumption of optical flow through dynamic processing, steerable filters, and motion thresholds so that PBOF can accurately extract super-pixel motions – particularly large-scale translation and in-plane rotation – while still extracting sub-pixel motion. Proof of concept is presented through various synthetic test cases followed by experimental validation, all showing good agreement.