I am trying to use RTAB-Map with a stereo camera (rubedos viper) and the map is being created upside down, the floor is up and the objects are inverted. I think that my optical frames are good oriented (first image, visualization in rviz of the pointcloud produced by the camera). The orientation in rtabmap should be with z-axis up but it is down (second image). I think that it is something related to the odometry calculation but I don't know why it is happening. Do you have any idea?
the imu are automatically published by the camera so I can't change them
aren't the camera node open source? One think you should make sure is that at least the gyro/acc data output of the IMU matches the imu frame (if not this would need to modify imu data -> if you cannot modify the ros node publishing the imu, you would have to create a intermediate node to switch gyro/acc parameters so they match the frame). Then if IMU frame is not aligned correctly with the cameras, then it is a staitc tf problem between the camera and imu frames. Can you show the imu frame in RVIZ too (with a rostopic echo at the same time of imu topic)?