rosbag2_to_pcd

The rosbag2_to_pcd package provides functionality to convert point cloud data from a ROS 2 rosbag file to PCD (Point Cloud Data) files. For each point cloud message in the specified topic, the package creates an individual PCD file.

Alternative (much more capable) tool:

• https://github.com/AIT-Assistive-Autonomous-Systems/ros2bag_tools#export

Installation

To install, follow the ROS 2 Humble Installation Guide and then execute:

mkdir -p ~/rosbag2pcd_ws/src
cd ~/rosbag2pcd_ws/src
git clone https://github.com/xmfcx/rosbag2_to_pcd.git
cd ~/rosbag2pcd_ws

sudo apt update
rosdep init
rosdep update
rosdep install -y --from-paths src --ignore-src --rosdistro $ROS_DISTRO

colcon build --symlink-install  --cmake-args -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_EXPORT_COMPILE_COMMANDS=1

Usage

Parameters

The node accepts the following parameters:

• path_bag: The absolute path to the rosbag2 file that you want to convert.
  • Example: /home/mfc/bags/rosbag2_2023_08_15-18_42_55 which contains:
    • /home/mfc/bags/rosbag2_2023_08_15-18_42_55/metadata.yaml
    • /home/mfc/bags/rosbag2_2023_08_15-18_42_55/rosbag2_2023_08_15-18_42_55_0.mcap
• topic_cloud: The topic that contains the point cloud data in the rosbag2 file.

By default, the parameters are sourced from the rosbag2_to_pcd.param.yaml file in the config directory. Modify this file’s default values or provide your own parameter file as needed.

Running the Node

Execute the following commands:

source ~/rosbag2pcd_ws/install/setup.bash
ros2 launch rosbag2_to_pcd rosbag2_to_pcd.launch.xml

Once launched, the node will process the rosbag file specified by the path_bag parameter. It will generate a PCD file for each point cloud message, storing them in a directory named <rosbag-name>_pcds adjacent to the rosbag2 folder.

The resulting PCD files use the timestamp of the point cloud message for naming, e.g., 1610472435-452138256.pcd.

Tips

To visually check which point cloud corresponds to which timestamp:

• Launch Rviz2 to view the point cloud.
• In a separate terminal, run:
  • ros2 topic echo /your_point_cloud_topic --field header.stamp
• Play your bag file.
• Pause the bag file playing by pressing space key when needed.
• Match the point cloud message’s timestamp with the corresponding PCD file name.

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