Optical-flow based on an edge-avoidance procedure

摘要

This paper presents a differential optical flow method which accounts for two typical motion-estimation problems: (1) flow regularization within regions of uniform motion while (2) preserving sharp edges near motion discontinuities i.e., where motion is multimodal by nature. The method proposed is a modified version of the well known Lucas–Kanade (LK) algorithm. While many edge-preserving strategies try to minimize the effect of outliers by using a line process or a robust function, our method takes a novel approach to solve the problem. Based on documented assumptions, our method computes motion with a classical least-squares fit on a local neighborhood shifted away from where motion is likely to be multimodal. In this way, the inherent bias due to multiple motion around moving edges is avoided instead of being compensated. This edge-avoidance procedure is based on the non-parametric mean-shift algorithm which shifts the LK integration window away from local sharp edges. Our method also locally regularizes motion by performing a fusion of local motion estimates. The regularization is made with a covariance filter which minimizes the effect of uncertainties due in part to noise and/or lack of texture. Our method is compared with other edge-preserving methods on image sequences representing different challenges.