[BUG] ValueError: namespace must be global

asked 2020-11-23 12:18:30 -0500

CodeurEnHerbe gravatar image

updated 2020-11-23 15:08:54 -0500

gvdhoorn gravatar image


I'm just starting with ROS and I downloaded a docker image with ROS kinetic with gazebo and RVIZ installed (https://hub.docker.com/r/ct2034/vnc-r...). I then installed TURTLEBOT3 to test it. It worked fine until I tried to use the camera TOPIC of the robot while gazebo is running.

I tried to do : rostopic echo /camera/rgb/image_raw and it made my gazebo crash with an error saying a processus has died. I looked a the log and found this error: "ValueError: namespace must be global".

This is probably a problem related to the fact that I use docker but I was unable to find what caused this.

Thanks for your time.

Log: /gazebo
[rosmaster.master][INFO] 2020-11-23 17:50:20,195: +PARAM [/camera/rgb/image_raw/theora/quality] by /gazebo
[rosmaster.master][INFO] 2020-11-23 17:50:20,196: +PARAM [/camera/rgb/image_raw/theora/keyframe_frequency] by /gazebo
[rosmaster.master][INFO] 2020-11-23 17:50:20,199: +PUB [/camera/rgb/camera_info] /gazebo http://9894914a40dc:32897/
[rosmaster.master][ERROR] 2020-11-23 17:50:20,312: Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosmaster/master_api.py", line 177, in validated_f
    code, msg, val = f(*newArgs, **kwds)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosmaster/master_api.py", line 435, in searchParam
    search_key = self.param_server.search_param(caller_id, key)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosmaster/paramserver.py", line 116, in search_param
    raise ValueError("namespace must be global")
ValueError: namespace must be global
edit retag flag offensive close merge delete


So rostopic echo usually listens to the topic you mention and spits it out on the terminal. Any reason you are trying to read the image on the terminal? Just trying to get some context

Akhil Kurup gravatar image Akhil Kurup  ( 2020-11-23 14:27:36 -0500 )edit

First I tried launching Rviz to display the camera output but I got an error there saying there is no data on the topic and it also threw the error above on the gazebo process.

I then tried juste displaying the topic data but the same error apeared

CodeurEnHerbe gravatar image CodeurEnHerbe  ( 2020-11-23 15:43:09 -0500 )edit

Are you sure the images are being published to /camera/rgb/image_raw? It is possible you are getting the topic wrong. Try using a rostopic list to see the available topics and then rostopic info to make sure they have sensor_msgs/Image type.

Akhil Kurup gravatar image Akhil Kurup  ( 2020-11-23 15:47:29 -0500 )edit

here is a part of the result of rostopic 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

and there is the rostopic info:

rostopic info /camera/rgb/image_raw Type: sensor_msgs/Image

Publishers: * /gazebo (http://9ccfe8216d87:42241/)

Subscribers: None

I'm sure this si the topic where turtlebot is sending his data, I have collegue who tried the same thing but not on a docker image and got no problem.

CodeurEnHerbe gravatar image CodeurEnHerbe  ( 2020-11-23 16:19:05 -0500 )edit

as soon as I try to rostopic echo /camera/rgb/image_raw, the gazebo process crash and the echo returns :

rostopic echo /camera/rgb/image_raw WARNING: no messages received and simulated time is active. Is /clock being published?

(I checked and /clock is being published)

CodeurEnHerbe gravatar image CodeurEnHerbe  ( 2020-11-23 16:21:59 -0500 )edit

Any updates on this?

rezenders gravatar image rezenders  ( 2021-01-05 13:50:10 -0500 )edit