save pose graph when merging map

[sunrentao]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses
Primary OS tested on	(Ubuntu)
Robotic platform tested on	( customized hardware )

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Description of contribution in a few bullet points

• when generate merged map , also generate merged posegraph, but I don't update rviz gui, so only indicate the file name with command line

Description of documentation updates required from your changes

• rosservice call /map_merging/merge_submaps "filename: ''the name you want"

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Future work that may be required in bullet points

• When merge pose graph, it should work as lifelong to decay old node.

[SteveMacenski]

Please add a space between ) {. Also you didn't indent your if/else code. Finally, remove all spaces between pointer accessors.

[SteveMacenski]

Looks good - small thing.

My action items after that's fixed:

• test locally with rviz plugin
• merge
• cherry pick to noetic / ROS2

[SteveMacenski]

You don't use this variable. You can just ignore the return type if you're not checking its validity.

[sunrentao]

Hello, done.

And I am developing the lifelong merge, I am planning to add a new service something like "lifelong merge", it works as lifelong to decay old node when merge pose graph , if you want, I can create another PR after I finish.

[sunrentao]

Hello, we have a problem here, for example, if I use lifelong mode, after about 20 minutes , the map will drift, the dock position in the map frame will not be 100% same as initial map.

What is your opinion about this problem ? Thank you.