CLIC

Continuous-Time Fixed-Lag Smoothing for LiDAR-Inertial-Camera SLAM

CLIC is a tightly-coupled multi-modal SLAM algorithms based on continuous-time fixed-lag smoothing, it supports a variety of sensor combinations, like the LiDAR-inertial and LiDAR-inertial-camera SLAM systems, and online timeoffset calibration is also naturally supported. More importantly, benefiting from the marginalization and the derived analytical Jacobians for optimization, the proposed continuous-time SLAM systems can achieve real-time performance regardless of the high complexity of continuous-time formulation.

Factor graphs of multi-sensor fusion. For more details, please refer to the paper. [arxiv]

Prerequisites

ROS (tested with Melodic)
Eigen3
Ceres 1.14
OpenCV 3.3
yaml-cpp
```
sudo apt-get install libyaml-cpp-dev
```
livox_ros_driver
~~Sophus~~ has been included in src/sophus_lib

Install

mkdir -p ~/catkin_clic/src
cd ~/catkin_clic/src
git clone https://github.com/APRIL-ZJU/clic.git
git clone https://github.com/Livox-SDK/livox_ros_driver.git
cd ~/catkin_clic
catkin_make
source devel/setup.bash

Example

Download ntu_viral_dataset or newer_college_dataset or LVI dataset or livox dataset.
Configure parameters in the config/ct_odometry_***.yaml file.
- config_path: the path of config folder
- bag_path: the file path of rosbag
Run on ntu viral dataset for example.
```
roslaunch clic odometry.launch config_path:=config/ct_odometry_ntu.yaml
```
The estimated trajectory is saved in the folder./src/clic/data.

Credits

This code was developed by Jiajun Lv and Xiaolei Lang from APRIL Lab in Zhejiang University.

For researchers that have leveraged or compared to this work, please cite the following:

@article{lv2023continuous,
  title={Continuous-Time Fixed-Lag Smoothing for LiDAR-Inertial-Camera SLAM},
  author={Lv, Jiajun and Lang, Xiaolei and Xu, Jinhong and Wang, Mengmeng and Liu, Yong and Zuo, Xingxing},
  journal={IEEE/ASME Transactions on Mechatronics},
  year={2023},
  publisher={IEEE}
}

Acknowledgement

The spline module is adapted from basalt.
The lidar fearure module is adapted from LIO-SAM and loam_livox.
The visual module is adapted from VINS-Mono.
The IMU initializer module is adapted from open_vins.

Thanks for their excellent job!

Licence

The code is released under the GNU General Public License v3 (GPL-3).