Subscribe to lidar node on another machine and run rviz

asked 2015-11-05 03:51:42 -0500

learner88
20 ●4 ●5 ●6

Hi,

I have 2 machines on the same network. Machine A has master ros uri and has lidar attached. It is the publisher of lidar topic. I wish to run rviz on machine B to view the output of lidar on machine A. I wrote a subscription method on machine B. When i run rviz, rviz subscribes to machine A instead of using the already subscribed node to machine A.

How do I ask rviz to get data from my subscription instead of having rviz subscribes again to lidar topic.

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Can you describe your exact setup, i.e., what nodes on what machine subscribing/publishing which topics - and also what kind of setup you want to achieve. For me, right now, it seems you want to do something that doesn't make sense.

dornhege ( 2015-11-05 04:18:01 -0500 )edit

1

Does your subscriber on MachineB publish anything? If you are modifying the incoming laser data and then re-publishing it, you could then on rviz, view only the new 're-published' topic.

ParitoshKelkar ( 2015-11-05 12:45:11 -0500 )edit

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answered 2015-11-06 00:04:03 -0500

Akif

3561 ●24 ●45 ●66 https://www.linkedin.c...

If you set

export ROS_MASTER_URI=http://<MACHINE_A_IP>:11311
export ROS_IP=<MACHINE_B_IP>

in your .bashrc file (located in your /home/<username> directory), and run source ~/.bashrc in the terminal, when you run rviz in that terminal, you will subscribe to topics in Machine A's ROS network.

Is this what you ask?

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Hi Akif, i am able to run rviz. but when i run roslaunch hector_slam_launch neato.launch, the GUI appeared has error status saying Fixed Frame [map] does not exist. Do you have any idea why? Thank u.

learner88 ( 2015-11-06 00:23:19 -0500 )edit

map frame should be published by your slam node. Can you run rosrun tf view_frames and post the resulting tf tree here?

Akif ( 2015-11-06 00:31:39 -0500 )edit

here is the tf tree: odom->base_link(Broadcaster: /map_to_odom; Avg rate: 96.613 Hz; Most recent transform: 1446792454.255,-0.007 sec old; Buffer len: 4.948sec) base_link->laser(Broadcaster: /base_frame_laser;Avg rate: 96.785Hz; Most recent transform: 1446792454.256,-0.008 sec old; Buffer len: 4.949

learner88 ( 2015-11-06 00:54:04 -0500 )edit

1

It seems like no one is transforming from map to odom. For now you can change "Global Options->Fixed Frame" option to odom in rviz. After that you can ask a separate question for your setup with hector slam.

Akif ( 2015-11-06 01:01:21 -0500 )edit

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answered 2015-11-05 20:35:24 -0500

learner88
20 ●4 ●5 ●6

Thank u dornhege and ParitoshKelkar.

@ParitoshKelkar: My subscriber on machine B does not do publishing. I get u. Thank you for your answer.

@dornhege: Sorry, I am not clear enough. Below is my setup:

Both machines are on the same network.

Machine A: Is the master ros uri. Is connected to a xv lidar and publishes scan data

Machine B: Subscribes to scan data. I wanted to make use of this data to show it on rviz.

However, when i run rviz, instead of showing the subscribed data, rviz subscribes again to xv lidar node on machine A. Paritosh has provided a solution to this which is to publish the subscribed data.

I wish to also ask if it is possible to run rviz on machine B and for rviz to subscribe data direct from machine A's lidar node. It seems possible, but I received an error status saying Fixed Frame [map] does not exist.

Thanks alot.

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Generally the Laserscan messages of the /scan topic of a lidar are assigned to the 'laser' frame. Try typing in 'laser' in the 'fixed frame' tab in rviz and see if that lets you visualize the scans.

ParitoshKelkar ( 2015-11-06 01:17:19 -0500 )edit

Thanks ParitoshKelkar! That worked for me!

Ktysai ( 2020-06-06 03:34:51 -0500 )edit

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Subscribe to lidar node on another machine and run rviz

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