When IMU mode is turned on, I found that the topic /visual_slam/vis/gravity sometimes appears and sometimes disappears in RVIZ2 (as shown in the picture).
I have a question, when does the IMU fusion mode of the latest version of cuvslam3.1 use IMU data? Is it to use IMU integration to make up when there are fewer feature points? Or is the IMU data added to the backend optimization process and processed together with the image feature points?