Two cameras and loop closure in the corridor

[kosmonauta144]

Please label it as a question :smiley: and thank you for your awesome work :heart:

I have a robot which has one realsense d435i looking forward and 2d lidar. Robot has to map a long corridor with many closed doors and not so much visual features. Odometry based on ICP is doing fine, but when I arrived at the end of the corridor and turn back and going through the corridor in opposite direction, the loop closure does not seems to happen. If I understand it correctly, the reason is because the robot does not take the same pictures as before because it's going in the opposite direction.

I am curious if adding second D435i looking backward could allow me to make loop closures more often and in result to correct the map better? I am going to check it soon with configuration shown here https://answers.ros.org/question/269459/rtabmap-with-two-stereo-cameras/ but I am curious if the idea seems to be correct.

Thank you in advance for your answer :bowing_man:

[matlabbe]

If you are feeding the laser scans to rtabmap node, and that Reg/Strategy is 1, rtabmap would be able to find proximity detection with laser scans (like shown in figure 4 of this paper), which works when the robot is coming back in another direction (assuming the lidar FOV > 180 deg).

Adding a backward camera can also help for visual loop closure detection in that situation.