Description

The code implemented in ROS projects a point cloud obtained by a Velodyne VLP16 3D-Lidar sensor on an image from an RGB camera. The example used the ROS package to calibrate a camera and a LiDAR from lidar_camera_calibration. In order to have points in a denser cloud, we interpolate the point cloud data by converting the point cloud to a range image and a bilinear interpolation with the armadillo library.

Interpolated point cloud

The white dots are the original point cloud of the Velodyne VLP-16 lidar. The colored dots are the interpolated point cloud.

Lidar and camera fusion

Requisites

• ROS Melodic or Noetic
• Velodyne repository

  cd ~/(your_work_space)/src
  git clone https://github.com/ros-drivers/velodyne.git -b melodic-devel
  cd ..
  catkin_make --only-pkg-with-deps velodyne

• PCL (Point Cloud Library) (tested with pcl 1.8)
• Armadillo (11.0.1 or higher)

  tar -xvf armadillo-11.1.1.tar.xz
  cd armadillo-11.1.1
  mkdir build
  cd build
  cmake ..
  make
  sudo make install

  Topics

Suscribed Topics

~/pointcloudTopic Input Point Cloud message. (sensor_msgs/PointCloud2)

~/imageTopic Input image message. (sensor_msgs/Image)

Published Topics

Lidar and camera fusion

~/points2 Output point cloud interpolated. (sensor_msgs/PointCloud2) ~/pcOnImage_image lidar point cloud projected on input image. (sensor_msgs/Image)

Interpolated point cloud

~/pc_interpoled Output point cloud interpolated. (sensor_msgs/PointCloud2)

Clone repository

    cd ~/catkin_ws/src
    git clone https://github.com/EPVelasco/lidar_camera_fusion.git
    cd ..
    catkin_make --only-pkg-with-deps lidar_camera_fusion

Ros Launch

You can use this rosbag to test the repository. Please note that the homogeneous camera-LiDAR matrix has inaccuracies. We are recalibrating the camera and LiDAR to reduce this error. However, you can get an idea of how the package works and how it merges the Realsense D435 camera and the Velodyne VLP16 LiDAR.

Rosbag play

  rosbag play ~/{your_rosbag path}/cam_lidar00.bag

Lidar and camera fusion with rosbag

  roslaunch lidar_camera_fusion vlp16OnImg_offline.launch 

Lidar and camera fusion with real sensors

  roslaunch lidar_camera_fusion vlp16OnImg.launch 

Interpolated point cloud

  roslaunch lidar_camera_fusion interpolated_vlp16.launch

Testing the package

LiDAR Odometry

Lidar odometry has been experimented with the original point cloud and with the interpolated point cloud. You need to install the FLOAM package, it is recommended to use the following fork. We prepared a rosbag for testing with the LiDAR odometry and LiDAR interpolation package. The rosbag is from a closed loop in an outdoor environment generated with a velodyne VLP16. It is necessary to modify the name of the topic in the launch file. Thus, to run FLOAM with the original point cloud you put the topic /velodyne_points, and to launch FLOAM with the interpolated lidar you have to put the topic

Launch FLOAM, interpolated_vlp16 and rosbag

roslaunch floam floam_experimets.launch
roslaunch lidar_camera_fusion interpolated_vlp16.launch
rosbag play {your/rosbag/file/address}/loop_8.bag

Results

The image shows the odometry results with the FLOAM package, where the path A and B are generated by the point cloud without interpolation and interpolated respectively. The test was performed after running the rosbag 4 times in a row.

Applications

Detection and depth estimation for domestic waste in outdoor environments by sensors fusion. Preprint

Citation

LiDAR data augmentation by interpolation on spherical range image

@inproceedings{velasco2023lidar,
  title={LiDAR data augmentation by interpolation on spherical range image},
  author={Velasco-S{\'a}nchez, Edison and de Loyola P{\'a}ez-Ubieta, Ignacio and Candelas, Francisco A and Puente, Santiago T},
  booktitle={2023 IEEE 28th International Conference on Emerging Technologies and Factory Automation (ETFA)},
  pages={1--4},
  year={2023},
  organization={IEEE}
}

Application of the method in depth estimation

@article{paez2022detection,
  title={Detection and depth estimation for domestic waste in outdoor environments by sensors fusion},
  author={P{\'a}ez-Ubieta, Ignacio de L and Velasco-S{\'a}nchez, Edison and Puente, Santiago T and Candelas, Francisco A},
  journal={arXiv preprint arXiv:2211.04085},
  year={2022}
}