Laser Odometry and Mapping (LOAM)
Laser Odometry and Mapping (LOAM) is a real-time method for state estimation and mapping using a 3D lidar. LOAM was developed by Ji Zhang and Sanjiv Singh. It is available as a ROS package. Watch LOAM in action on the Schenley Bridge.
The program contains two major threads running parallel. An “odometry” thread computes motion of the lidar between two sweeps at a higher frame rate. It also removes distortion in the point cloud caused by motion of the lidar. A “mapping” thread takes the undistorted point cloud and incrementally builds a map while simultaneously computing the pose of the lidar on the map at a lower frame rate. The lidar state estimation is combination of the outputs from the two threads.
If an IMU is available, the orientation (integrated from angular rate) and acceleration measurements are used to deal with general motion of the lidar, while the program takes care of linear motion.