dual_laser_merger

ROS 2 Package to merge dual lidar scan data. This package provide a node to concatenate pointcloud. First the laser scans are coverted to pointclouds which is then transformed to target_frame and concatenated. After this concatenated pointcloud is convert to laserscan.

Build from source

This package currently works on ROS 2 Distributions: Humble, Jazzy, Rolling

mkdir laser_merger_ws/src -p
cd laser_merger_ws/src
git clone https://github.com/pradyum/dual_laser_merger.git
cd ..
rosdep install --from-paths src --ignore-src -r -y
colcon build --symlink-install
source install/setup.bash

Example Demo using recorded bag file

This demo shows merging of laser scan data from 2 lidars.

ros2 launch dual_laser_merger demo_laser_merger.launch.py

Requirements

1. Lidar 1 scan topic, the messages in the topic are required to have frame_id.

   ~$ ros2 topic info /lidar1/scan
      Type: sensor_msgs/msg/LaserScan
   

2. Lidar 2 scan topic, the messages in the topic are required to have frame_id.

   ~$ ros2 topic info /lidar2/scan
      Type: sensor_msgs/msg/LaserScan
   

3. TF from Lidar 1 (laser_1) and Lidar 2 (laser_2) to Target frame (lsc_mount)

~$ ros2 topic echo /tf_static 
transforms:
  - header:
      stamp:
        sec: 1729076136
        nanosec: 564956753
      frame_id: lsc_mount
    child_frame_id: laser_1
    transform:
      translation:
        x: 0.321967
        y: 0.221817
        z: 0.0
      rotation:
        x: 0.3826834321814926
        y: 0.9238795325873352
        z: 3.9573888241688663e-14
        w: -9.553981776262265e-14

transforms:
  - header:
      stamp:
        sec: 1729076136
        nanosec: 580013258
      frame_id: lsc_mount
    child_frame_id: laser_2
    transform:
      translation:
        x: -0.321967
        y: -0.221817
        z: 0.0
      rotation:
        x: -0.9238795324744832
        y: 0.38268343245394154
        z: -9.553981775095244e-14
        w: -3.957388826986303e-14

Usage

This is included as a launch file as shown

from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource


def generate_launch_description():

    ld = LaunchDescription()

    dual_laser_merger_node = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            [
                f"{get_package_share_directory('dual_laser_merger')}/dual_laser_merger.launch.py"
            ]
        ),
        launch_arguments={
            'laser_1_topic': 'lidar1/scan',
            'laser_2_topic': 'lidar2/scan',
            'merged_topic': 'merged/scan',
            'publish_rate': '100',
            'target_frame': 'lsc_mount',
            'angle_increment': '0.001',
            'scan_time': '0.067',
            'range_min': '0.01',
            'range_max': '25.0',
            'min_height': '-1.0',
            'max_height': '1.0',
            'angle_min': '-3.141592654',
            'angle_max': '3.141592654',
            'use_inf': 'false',
        }.items(),
    )

    ld.add_action(dual_laser_merger_node)

    return ld

The following arguments can be changed as needed

Argument	Description
laser_1_topic	Input topic name of first laser scan
laser_2_topic	Input topic name of second laser scan
merged_topic	Output topic name of merged laser scan
publish_rate	Merged laser scan publisher loop delay in milliseconds $( frequency = \frac{1}{publish\_rate} \times 1000 )$
target_frame	The target TF frame on which the merged laser scan will be publisher.
angle_increment	angular distance between measurements [rad] of merged laser scan data
scan_time	time between scans [seconds] of merged laser scan data
range_min	minimum range value [m] of merged laser scan data
range_max	maximum range value [m] of merged laser scan data
min_height	minimum height from target frame in which the scan ports are accepted [m]
max_height	maximum height from target frame in which the scan ports are accepted [m]
angle_min	minimum angle value [rad] of merged laser scan data
angle_max	maximum angle value [rad] of merged laser scan data
use_inf	if true reports infinite values as +inf, else reported as range_max + 1

Issues

If you encounter any bugs, issues, or have suggestions for improvements, feel free to raise them by opening an issue on this repository. We appreciate your feedback and contributions to make this package better!