I. Introduction
With the rapid development of the autonomous driving industry, many high-level applications nowadays come with a prebuilt HD vector map. A typical HD vector map stores a set of vectorized 3D traffic elements such as lane lines, traffic signs, poles, and the lane topology. A few standards have been proposed to formalize the vector map’s specification, e.g., OpenDrive [1], Lanelet2 [2]. Localization on the prebuilt vector maps is a crucial prerequisite of these applications.