3D_slam_tools

Tools to work along side with LOAM 3D lidar slam and Octomaping. The main goal here is to generate a 2D occupancy map from a 3D Map.

Generated 3D Map and Sliced Map with LOAM and surrounding tools

Setup Environment

• ROS, obviously (melodic or kinetic only)

Create a new ros workspace, then :

• Clone LOAM Velodyne Mapping, with dynamic object removal
• sudo apt-get install ros-$ROS_DISTRO-navigation ros-$ROS_DISTRO-octomap-mapping

Compilation

This package is tested on ROS Kinetic. For ROS Melodic, pls refer here

cd catkin_ws/
catkin_make -DCMAKE_BUILD_TYPE=Release --pkg loam_velodyne 3D_Slam_tools

Record ROS bag file

Bag file is recorded to run the SLAM remotely after the recording process. Here Velodyne and IMU are used in the recording process of an indoor environment.

Or, you can download a sample rosbag file for testing, here

1) Sensor Setup for Velodyne

Follow the velodyne setup tutorial and run the .launch file for pointcloud visualization on rviz.

2) Sensor Setup for VectorNav IMU (Optional)

If IMU is used (Vectornav 100), use the ROS package imu_vn_100. Run the launch file below to receive the imu data on ROS topic /imu/imu and /imu/rpy.

sudo chmod 666 /dev/ttyUSB0
roslaunch 3D_Slam_tools imu_vn_100.launch

3) Robot base Odom readings

Get encoder odometry from turtlebot after 'bringup' the robot.

roslaunch turtlebot_bringup minimal.launch
rostopic echo /odom

Record the bag file!!

After setup, conduct data collection via rosbag with a command

rosbag record -a

When ctrl-c, .bag file will be saved in current working directory

Run Tools

Here we will have the ROS bag file of the velodyne point clouds.

1) 3D SLAM with input velodyne ROS Msg

Run with LOAM package

roslaunch 3D_Slam_tools loam_project.launch

Subsequently open a seperate terminal to run a rosbag file. (You can even run LOAM SLAM on the fly)

To save .pcd and .bt files on fly, Run this on a seperate terminal:

rosrun 3D_Slam_tools pcd2octomap_node

**For tuning, edit config file at config/param.yaml.

2) PCD Straigtener

When a 3d map is generated, there's a tendency that the map's floor is not exactly normal to the z-axis. Thus, user will need to straighten the output .pcd file of a 3D map (by using teleop of turtlebot for convenience sake).

roslaunch 3D_Slam_tools straightener.launch input_path:="$HOME/catkin_ws/output_pcd0.pcd" output_path:="$HOME/catkin_ws/straighten_map.bt"

User will need to use the arrow keys to control the rotation of the map. Once completed, press ctrl-c to get the output .bt octomap file.

3) 3D Octomap to 2D Occupancy map

Slice .bt file to occupancy map .pgm image file. Please specify the $PATH_TO_BT_FILE, optional float value of $Z_MIN and $Z_MAX. Both z-value are respected to the velodyne's position.

# Run the map file
roslaunch 3D_Slam_tools octomap_mapping.launch path:=$PATH_TO_BT_FILE z_min:=$Z_MIN  z_max:=$Z_MAX
# Run map_saver in another terminal to save the map. 
rosrun map_server map_saver

Convert input .pgm to transparent .png map. Then user can use image editting tool to edit the map imagery.

convert input.pgm  -fuzz 20% -transparent white output.png

Note

Odometry Handler Node

(TO BE DEVELOPED)

If IMU is used, this node will get /imu sensor msg, /point_cloud message, then transform it in a meaningful way to the SLAM node. Currently using vn100 imu for testing.

If encoder odom is used, /odom will be subcribed and publish to /tf, in terms of "odom_init"->"camera_init"->"encoder_odom".

To run the individual node:

rosrun 3D_Slam_tools odom_handler

Troubleshooting

• Compilation on Melodic
  • In melodic, PCL 1.8 is being used, which will resulted in a run time error. (PCL 1.7 is ok)
    • Error Printout: [multiScanRegistration-2] process has died [pid 19187, exit code -11
  • make sure that you are using pcl 1.9. This issue is mentioned here.
  • As for Ubuntu 18, PCL 1.9 is not available in debian, thus there's a need to compile from source.
  • Download the PCL 1.9 release: pcl github release
  • To compile pcl from source, please refer to here
    • Refer to 2. 自己编译安装PCL 1.9 and copy paste those command lines
  • Once the compilation is done, edit these few lines in the CmakeList in loam_velodyne:

    find_package(PCL 1.9.1 REQUIRED)
    include_directories(${PCL_INCLUDE_DIRS})
    link_directories(${PCL_LIBRARY_DIRS})
    add_definitions(${PCL_DEFINITIONS})

  • Then... Continue with the compilation of LOAM