  We present a novel framework for floor plan-based, full six degree-of-freedom
LiDAR localization. Our approach relies on robust ceiling and ground plane
detection, which solves part of the pose and supports the segmentation of
vertical structure elements such as walls and pillars. Our core contribution is
a novel nearest neighbour data structure for an efficient look-up of nearest
vertical structure elements from the floor plan. The registration is realized
as a pair-wise regularized windowed pose graph optimization. Highly efficient,
accurate and drift-free long-term localization is demonstrated on multiple
scenes.
