ROS wrapper for ORB-SLAM3

A ROS wrapper for ORB-SLAM3. The main idea is to use the ORB-SLAM3 as a standalone library and interface with it instead of putting everything together. For that, you can check out this package.

Tested with ORB-SLAM3 V1.0, primarily on Ubuntu 20.04.

• Pros:
  • Easy to update ORB-SLAM3 indepedently.
  • Easy to replace different variants that are not built for ROS.
• Cons:
  • Dependent on the exposed APIs from ORB-SLAM3.
  • Development involves more steps (1. Make changes in ORB-SLAM3 library -> 2. Build ORB-SLAM3 -> 3. Change the roswrapper if necessary -> 4. Test).
  • Might break when dependencies or upstream changes.

Installation

General guide: first, install ORB-SLAM3 normally with all of its dependencies (any location is fine). Then, install this package in a catkin build environment.

1. ORB-SLAM3

• Install the prerequisites.
• Clone ORB-SLAM3:

  cd ~
  git clone https://github.com/UZ-SLAMLab/ORB_SLAM3.git ORB_SLAM3

• Make changes to the source code if necessary to build successfully. For Ubuntu 20.04, you will need to change CMakeList from C++11 to C++14. I have incorporated the changes in this fork.
• Build:

  cd ORB_SLAM3
  chmod +x build.sh
  ./build.sh

• Make sure that libORB_SLAM3.so is created in the ORB_SLAM3/lib folder. If not, check the issue list from the original repo and retry.

2. orb_slam3_ros_wrapper

• Clone the package. Note that it should be a catkin build workspace.

  cd ~/catkin_ws/src/
  git clone https://github.com/thien94/orb_slam3_ros_wrapper.git

• Open CMakeLists.txt and change the directory that leads to ORB-SLAM3 library at the beginning of the file (default is home folder ~/)

  
  cd ~/catkin_ws/src/orb_slam3_ros_wrapper/
  nano CMakeLists.txt

Change this to your installation of ORB-SLAM3. Default is ~/

set(ORB_SLAM3_DIR $ENV{HOME}/ORB_SLAM3 )

- Build the package normally.

cd ~/catkin_ws/ catkin build

- Next, copy the `ORBvoc.txt` file from `ORB-SLAM3/Vocabulary/` folder to the `config` folder in this package. Alternatively, you can change the `voc_file` param in the launch file to point to the right location.

- (Optional) Install `hector-trajectory-server` to visualize the trajectory.

sudo apt install ros-[DISTRO]-hector-trajectory-server

- If everything works fine, you can now try the different launch files in the `launch` folder.

## 3. How to run

### EuRoC dataset:

- In one terminal, launch the node:

roslaunch orb_slam3_ros_wrapper euroc_monoimu.launch

- In another terminal, playback the bag:

rosbag play MH_01_easy.bag

Similarly for other sensor types.

# Topics
The following topics are published by each node:
- `/orb_slam3/map_points` ([`PointCloud2`](http://docs.ros.org/en/melodic/api/sensor_msgs/html/msg/PointCloud2.html)): all keypoints being tracked.
- `/orb_slam3/camera_pose` ([`PoseStamped`](http://docs.ros.org/en/melodic/api/geometry_msgs/html/msg/PoseStamped.html)): current left camera pose in world frame, as returned by ORB-SLAM3.
- `tf`: transformation from camera frame to world frame.

# Params
- Enable / disable pangolin viewer: `enable_pangolin`
- For monocular/stereo case, use `world_roll`, `world_pitch`, `world_yaw` in the launch file to rotate the world frame if necessary (otherwise the first KF will be the world frame). The world frame will be rotated by the provided roll-pitch-yaw angles (in rad) in that order.