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orb_slam2_ros

A ROS wrapper for ORB_SLAM2.

Prerequisite

cd orb_slam2_core/Vocabulary
tar -xf ORBvoc.txt.tar.gz

Typical Use (monocular fisheye)

  1. Build map prior to the deployment. (offline)
  2. Deploy with localization mode enabled. (online)

1. Launch with remapped image_topic

roslaunch orb_slam2_ros mono_fisheye.launch image_topic:=<fisheye_image_topic> fisheye_calibration_file:=fisheye_starling2_front_modalai.yaml resize_factor:=2.0
  • On Starling2 (Max) Voxl2: fisheye_image_topic:=/ifs/tracking_front
  • Calibration files are located at ./config/
  • The size (and thus resolution) of an image is resized (divided) by the factor of resize_factor.

2. Turn mapping mode on

  • SLAM is initiated as SLAM (localization+mapping) mode by default.

3. Build map

  • One can initialize SLAM by moving the vehicle/camera around.
  • You will need sufficient and consistent disparity in order to initialize monocular SLAM.
  • Move the vehicle around, taking care not to lose track.
  • Make sure closing loop(s) and diversifying viewpoints.

4. Save map

rosservice call /orb_slam2_<type>/save_map <map_file_name>

  • Don't include the extension, i.e., .bin.

    • rosservice call /orb_slam2_ros/save_map ftrc_indoor is a good example.

  • The map and the initial vehicle pose will be saved at ./resource/

    1. map: ./resource/<map_file_name>.bin
    2. vehicle pose (when the SLAM is initialized): ./resource/<map_file_name>_initial_tf.bin

Note

the ORB_SLAM2 itself has nothing to do with the vehicle pose and the reference frame of ORB_SLAM2 is the camera frame (right-down-forward) when the system is initialized.

5. Relaunch with map file name

roslaunch orb_slam2_ros mono_fisheye.launch image_topic:=<fisheye_image_topic> fisheye_calibration_file:=fisheye_starling2_front_modalai.yaml resize_factor:=2.0 load_map:=true map_file_name:=<map_file_name>
  • if you want localization-only with prior map:
    • rosservice call /orb_slam2_<type>/set_localization_mode true
    • The system is initiated with mapping mode by default, thus one must explicitly turn localization-only mode on.
    • Note that you must have launched with load_map:=true map_file_name:=<map_file_name>
    • type: mono/stereo/rgbd

6. Utilities

  1. Adjust scale error of monocular vision SLAM. defaults are 1.
    • rosservice call /orb_slam2_<type>/rescale <scale_x> <scale_y> <scale_z>
    • Scale might be heterogeneous.
  2. Adjust offset of origin with respect to which the estimate is resolved.
    • rosservice call /orb_slam2_<type>/set_offset <x> <y> <z> <roll_deg> <pitch_deg> <yaw_deg>
    • This shifts origin.
  3. Filter map point cloud.
    • rosservice call /orb_slam2_<type>/set_mopp <minimum_observation_per_point>
    • Only keyframes with larger than minimum_observation_per_point map points will be included in the published map point cloud.
    • This may filter out outliers.

Currently supported types

  1. monocular
  2. monocular fisheye (rectified via fisheye adaptor)
  3. stereo
  4. stereo fisheye (rectified via two fisheye adaptors)