What is the LMDB database (map representation)?

[Mechazo11]

Dear isaac_ros_visual_slam developers,

Thank you very much for making isaac_ros_visual_slam package with its source code made publicly available.

I am going through Raffallo Bonghi's webinar (I think it was published a few years ago) on this package and found the detailed walk through of each subsystems very interesting.

I am trying to understand the LMDB databsae (map) module as shown below

However, I couldn't find any information regarding the mapping representation block. Is it a directed chain of keyframes (similar to ORB-SLAM3, GTSAM) or is it something different? Does it have any connection to the costmap based environment representation used by downstream software stack like Nav2?

Best,
@Mechazo11