linefit_ground_segmentation

Here is an enhanced implementation of the ground segmentation algorithm for Livox Solid-State Lidar which originally proposed in

@inproceedings{himmelsbach2010fast,
  title={Fast segmentation of 3d point clouds for ground vehicles},
  author={Himmelsbach, Michael and Hundelshausen, Felix V and Wuensche, H-J},
  booktitle={Intelligent Vehicles Symposium (IV), 2010 IEEE},
  pages={560--565},
  year={2010},
  organization={IEEE}
}

The linefit_ground_segmentation package contains the ground segmentation library. A ROS interface is available in linefit_ground_segmentation_ros

The library can be compiled separately from the ROS interface if you're not using ROS.

Installation

Requires the following dependencies to be installed:

• catkin_simple https://github.com/catkin/catkin_simple.git
• eigen_conversions sudo apt install ros-noetic-eigen-conversions

Compile using your favorite catkin build tool (e.g. catkin build linefit_ground_segmentation_ros)

Launch instructions

The ground segmentation ROS node can be launch by executing roslaunch linefit_ground_segmentation_ros segmentation.launch. Input and output topic names can be specified in the same file.

Getting up and running with your own point cloud source should be as simple as:

1. Change the input_topic parameter in segmentation.launch to your topic.
2. Adjust the sensor_height parameter in segmentation_params.yaml to the height where the sensor is mounted on your robot (e.g. KITTI Velodyne: 1.8m)

Parameter description

Parameters are set in linefit_ground_segmentation_ros/launch/segmentation_params.yaml

This algorithm works on the assumption that you known the height of the sensor above ground. Therefore, you have to adjust the sensor_height to your robot specifications, otherwise, it will not work.

The default parameters should work on the KITTI dataset.

Ground Condition

• sensor_height Sensor height above ground.
• max_dist_to_line maximum vertical distance of point to line to be considered ground.
• max_slope Maximum slope of a line.
• min_slope Minimum slope of a line.
• max_fit_error Maximum error a point is allowed to have in a line fit.
• max_start_height Maximum height difference between new point and estimated ground height to start a new line.
• long_threshold Distance after which the max_height condition is applied.
• max_height Maximum height difference between line points when they are farther apart than long_threshold.
• line_search_angle How far to search in angular direction to find a line. A higher angle helps fill "holes" in the ground segmentation.
• gravity_aligned_frame Name of a coordinate frame which has its z-axis aligned with gravity. If specified, the incoming point cloud will be rotated, but not translated into this coordinate frame. If left empty, the sensor frame will be used.

Segmentation

• r_min Distance at which segmentation starts.
• r_max Distance at which segmentation ends.
• n_bins Number of radial bins.
• n_segments Number of angular segments.

Other

• n_threads Number of threads to use.
• latch Latch output point clouds in ROS node.
• visualize Visualize the segmentation result. ONLY FOR DEBUGGING. Do not set true during online operation.