We present an active simultaneous localisation and mapping system that optimises the pose of the sensor for the 3D reconstruction of an environment, while a 2D Rapidly-Exploring Random Tree algorithm controls the motion of the mobile platform for the ground exploration strategy. You can find a video demo in simulation here: https://www.youtube.com/watch?v=NAPj3_A2e74.

The code has been only tested in Ubuntu 18.04 with ROS Melodic.
To use it, the steps are those common to any ROS package, which are:

1. Move and install outside the ROS workspace the uncertainty octomap package: aslam_system/octomap

2. Compile the workspace where this repository is located.

Note: some dependencies may have to be installed manually.

1. Run main launch file, which includes yocs_cmd_vel_mux, slam_gmapping, move_base_turtlebot3_omni, octomap_uncertainty_server_node, rviz:
   roslaunch aslam_bringup aslam_system.launch

2. Run 2D RRT exploration:
   roslaunch aslam_bringup rrt_simple.launch

3. Run optimal camera pose planner:
   roslaunch aslam_bringup planner.launch

Here, we should have all the required nodes and services ready. To start exploration:

6. Start calling the service /optimize_current_pose (offered by the planner) to estimate the camera's next best pose for exploration. To call it in a loop, use the script:
   roscd aslam_bringup/
./optimize_service_loop.sh

7. Start the 2D exploration system. You can follow the instructions from here.
   It requieres 5 points to be published in the /clicked_point topic. It can be done using rviz, and must follow this order:

1. top-left
2. bottom-left
3. bottom-right
4. top-right
5. initial point

At this point, the robot should start navigating towards frontiers.

If the robot gets stucked, teleop_key_turtlebot3.launch allows to move it manually:
roslaunch aslam_bringup teleop_key_turtlebot3.launch

To know the value representing the number of voxels added to the 3D map, the service /octomap_server/get_map_voxels can be called:
rosservice call /octomap_server/get_map_voxels "{}"

To know the value representing the information offered by the 3D map, the service /octomap_server/get_map_info can be called:
rosservice call /octomap_server/get_map_info "{}"

If you use this code, please cite the related paper:

@article{lluvia2023camera,
  author={Lluvia, Iker and Lazkano, Elena and Ansuategi, Ander},
  journal={IEEE Access},
  publisher={IEEE},
  title={Camera pose optimisation for 3D mapping},
  year={2023},
  volume={11},
  number={},
  pages={9122-9135},
  doi={10.1109/ACCESS.2023.3239657}
}

Iker Lluvia. Autonomous and Intelligent Systems, Tekniker.