Errors encountered when performing RTAB-Map SLAM with a drone equipped with a D435i camera in Gazebo simulation

[5dollars]

I am currently able to simulate a drone equipped with a D435i camera in Gazebo and perform RTAB-Map SLAM. However, I encounter the following issues. I suspect the problem might be related to time synchronization or that the RGBD and depth camera images are not synchronized. But I'm not sure how to configure this properly in the Gazebo world. Could you please help me?

ERROE:
[ INFO] [1741680777.885243246, 11216.723000000]: Odom: quality=59, std dev=0.019678m|0.032085rad, update time=0.083656s, delay=0.121000s
[ WARN] [1741680777.973223638, 11216.788000000]: The time difference between rgb and depth frames is high (diff=0.041000s, rgb=11216.714000s, depth=11216.673000s). You may want to set approx_sync_max_interval lower than 0.02s to reject spurious bad synchronizations or use approx_sync=false if streams have all the exact same timestamp.
[ INFO] [1741680778.062530304, 11216.857000000]: Odom: quality=60, std dev=0.024384m|0.035857rad, update time=0.085428s, delay=0.143000s
[ WARN] [1741680778.178451271, 11216.940000000]: The time difference between rgb and depth frames is high (diff=0.074000s, rgb=11216.861000s, depth=11216.787000s). You may want to set approx_sync_max_interval lower than 0.02s to reject spurious bad synchronizations or use approx_sync=false if streams have all the exact same timestamp.


Here’s a video of my experiment—hope it helps as a reference! Thank you!
https://drive.google.com/file/d/1a5c-NdHJ48umRK6CkXYwYBKRMeS_c-AV/view?usp=sharing

[matlabbe]

40 ms or 74 ms difference is kinda high. For good synchronization, images should be sync under 1 ms. Difficult to say what is wrong, but doublecheck what kind of camera plugins you are using to emulate a RGB-D camera, normally I think is should be possible to have a plugin that would render the color and depth images exactly at the same time and publish them with exactly the same stamp. You may search or ask on https://robotics.stackexchange.com if someone else had issue with RGB-D camera synchronization in gazebo.