Sampson Distance: A New Approach to Improving Visual-Inertial Odometry's Accuracy

In this paper, we propose a new scheme based on the Sampson distance (SD) to describe visual feature residuals for visual-inertial odometry (VIO). Unlike the epipolar-constraint-based SD for visual odometry (VO), the proposed SD is formulated based on the perspective projection constraint. We proved in theory that the proposed SD retains the good properties of those earlier SD criteria in the literature of VO and it represents a visual feature residual more accurately than the prevailing transfer distance (TD) in existing VIO methods. We formulate three distance criteria, including TD, reprojection error (RE), and SD, and compared their performances by simulation. The results show that the SD is much more accurate than the TD and it is a very accurate estimate of the gold standard criteria.RE. Based on the SD, we modified VINS-Mono by replacing its TD-based visual residuals with the SD-based residuals and study the SD's efficacy in pose estimation by experiments with several public datasets. The results reveal that the SD-based VINS-Mono has a substantial improvement over the original VINS-Mono in pose estimation accuracy. This indicates that the SD is a better distance criterion than the TD for representing visual feature residuals. The proposed SD may find its applications to broader areas in computer vision and robotics.