How to transmit the actual submap data to the mapping server?

[zongyang-chen]

Dear maplab team,
Firstly, thanks for your great projects.

I'm very interested in the work of "Multi-robot mapping and online operation". I have tested the "Maplab Server Euroc Experiment" on only one computer platform and it can work well. I have understand the workflow of maplab server system. During the multi-robot mapping and online operation, each robot mapping node will save submap into a "submap_xx directory" at regular intervals and publish a map update notification topic to the maplab server. The topic only contains the robot name and the map folder of the new map update, but it does not contain the actual submap data. Upon the maplab server receives the map update notification message, it will load the corresponding the submap from the "submap_xx directory" and try to emerge them.

Now, I want to test the multi-robot mapping system on multi-robot computer platforms. Specifically, both the odometry estimation node and the mapping node run onboard each robot, and the server node runs on one of the robots. The submap will be saved on each robot's own onboard computer. When the server receives a map update notification, it cannot load the submap data from other robots because the submap does't exist in the server robot.

So, I want to know that how can I transmit the actual submap data to server node? Not only containing the robot name and the map folder of the new map update so that I can apply the muli-robot mapping system on real-world mutli-robot platforms.

I would greatly appreciate if you can response to me. @smauq