It's using ICP to register sucessive lidar scans. All three lidars are calibrated so the relative positions are known and the data from all three can be combine

It's using ICP to register sucessive lidar scans. All three lidars are calibrated so the relative positions are known and the data from all three can be combined. https://en.m.wikipedia.org/wiki/Iterative_closest_point https://en.m.wikipedia.org/wiki/Iterative_closest_point This alone isn't SLAM but can be used for odometry as part of a SLAM system.