orb_slam2_ros

A ROS wrapper for ORB_SLAM2.

Prerequisite

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

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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.

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Currently supported types

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