Hi! I am running Rtabmap with ROS Kinetic, Ubuntu 16.04. whenever I ran Rtabmap's launch file, I got this warning:
Memory.cpp:810::addSignatureToStm() Very large angular variance (67953.453125) detected! Please fix odometry twist covariance, otherwise poor graph optimizations are expected and wrong loop closure detections creating a lot of errors in the map could be accepted.
I am using the Realsense 435 for camera topics; Hokuyo UST-20LX for scan, and turtlebot for wheel odometry.
The covariance is ok for 2D slam. Unfortunatly, with the version you are using, the warning appears when any of the angular variance is set high. This has been fixed in recent version where only yaw variance is checked for that warning if Reg/Force3DoF is true. In your case, the warning should not appear. It is safe to ignore the warning in your case (or update rtabmap to newest version from source to suppress this warning).