rqt_graph when playing a rosbag

Question

Hello, I am really new with ROS and I am having some problems with rqt_graph. I would like to play a rosbag file and watch all the nodes and topics with rqt_graph as it was during execution. Therefore, I run:

$> rosbag play rosbag_name.bag ---- Terminal 1

$> rqt_graph ---- Terminal 2

Then, I can only see:

https://drive.google.com/file/d/1-AjzLNJEjtB5K1At-A9t_BOg5lxOG8BC/view

As I show in the previous image, I can only find a node with the name /play_.... Does it mean that I cannot watch all the nodes when playing a rosbag? Or is there any way to play the bag and plot the nodes graph?

Thank you very much in advance. I have tried almost everything but I was not able to make it work.

Best regards

---

Originally posted by rkblack on ROS Answers with karma: 1 on 2018-07-26

Post score: 0

Answer 1

This is entirely correct, you will not be able to see the nodes as they were during recording because the don't exist on playback.

A rosbag only records messages published on topics, not the existence of the nodes themselves. So when you play the rosbag back again all you will see is the playback node. This single node is now publishing all the recorded messages that were originally produced by many different nodes.

Hope this makes sense.

---

Originally posted by PeteBlackerThe3rd with karma: 9529 on 2018-07-26

This answer was ACCEPTED on the original site

Post score: 1

---

Original comments

Comment by rkblack on 2018-07-26:
It totally make sense. Thank you very much PeteBlackerThe3rd!