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Why are these topics appearing?

asked 2017-07-25 07:10:05 -0500

pitosalas gravatar image

updated 2017-07-25 18:17:58 -0500

jayess gravatar image

This is a basic question. I've "installed" all the bits for a Turtlebot3 on my ubuntu running in vmware.

I have run roscore.

I have explicitly run a single script which creates a single new topic, cmd_vel.

But when I list rostopic list is see a long list of topics (see below).

It is clear that those topic come from the Turtlebot3 installed code. But my question is what ended up "invoking it"? As the only thing I've run are roscore and my little script, lots of other code must be in play to declare those topics.

Can someone please clarify?

Here's the list:

/camera/depth/camera_info
/camera/depth/image_raw
/camera/depth/points
/camera/parameter_descriptions
/camera/parameter_updates
/camera/rgb/camera_info
/camera/rgb/image_raw
/camera/rgb/image_raw/compressed
/camera/rgb/image_raw/compressed/parameter_descriptions
/camera/rgb/image_raw/compressed/parameter_updates
/camera/rgb/image_raw/compressedDepth
/camera/rgb/image_raw/compressedDepth/parameter_descriptions
/camera/rgb/image_raw/compressedDepth/parameter_updates
/camera/rgb/image_raw/theora
/camera/rgb/image_raw/theora/parameter_descriptions
/camera/rgb/image_raw/theora/parameter_updates
/clock
/cmd_vel
/joint_states
/mobile_base/commands/motor_power
/mobile_base/commands/reset_odometry
/mobile_base/commands/velocity
/mobile_base/events/bumper
/mobile_base/events/cliff
/mobile_base/sensors/imu_data
/odom
/rosout
/rosout_agg
/tf
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answered 2017-07-25 08:39:30 -0500

Akif gravatar image

Possibly you are running RViz or something similar. If you have subscribers, topics will appear. You can check with rostopic info.

For example rostopic info /camera/depth/camera_info will give you publishers and subscribers if there exists any.

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I guessed something like that, but where or what or how did RViz get run? If it's installed (rosdep) at all does it always run?

pitosalas gravatar image pitosalas  ( 2017-07-25 08:41:10 -0500 )edit

Of course, no. We can get a better idea if you can post the output of rostopic info /camera/depth/camera_info for example.

Akif gravatar image Akif  ( 2017-07-25 08:53:15 -0500 )edit

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Asked: 2017-07-25 07:10:05 -0500

Seen: 193 times

Last updated: Jul 25 '17