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asked 2015-03-10 01:14:22 -0500

rdhn gravatar image

I am trying to visualize the image stream from Xtion. I am able to see it on RVIZ but the

rosrun image_view image_view image:=/camera/rgb/image_color

command is giving me a blank screen. roswtf gives me this warning

WARNING The following node subscriptions are unconnected: * /image_view_1425967765955436448: * /camera/rgb/image_color

Can you please explain what is happening?

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answered 2015-03-10 01:22:11 -0500

Valts gravatar image

That warning indicates that nothing is being published to the /camera/rgb/image_color topic, but that the image_view has successfully subscribed to it. You should verify that an image from your xtion is indeed published to that topic. To do that, you can use "rostopic hz /camera/rgb/image_color" command. This will output the rate at which images are being published to that topic. If you find that there is nothing being published, use either "rostopic list" or "rosrun rqt_graph rqt_graph", to figure out the correct topic name that you should use. Otherwise you can refer to RViz, under Display types - check which topic you're subscribed to for your Image and check for spelling mistakes.

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In RViz I was subscribing to /camera/rgb/image_raw. Subscribing to this topic through image_view did the trick but my question is why doesn't Rviz give me /camera/image or /camera/rgb/image_color as a topic to subscribe in its Image Topic list.

rdhn gravatar imagerdhn ( 2015-03-10 01:35:15 -0500 )edit

Because, as I mentioned, no such topic is being published. Your Xtion drivers are not publishing those topics so there is nothing to subscribe in either Rviz or ImageView. Perhaps you can share some info about how you run the Xtion and why you think that the topics should exist and I'll try to help

Valts gravatar imageValts ( 2015-03-10 01:57:03 -0500 )edit

I am not certain which topics my camera drive are publishing but I am assuming that they must be publishing ../image_raw and ../camera_info So my first question is how to use this published topics and and subscribe to mono or color image which image_proc publishes.

rdhn gravatar imagerdhn ( 2015-03-10 04:42:54 -0500 )edit

After running the image_proc node ROS_NAMESPACE=camera rosrun image_proc image_proc I get this warning So my previous assumption that my camera drive is publishing /camera/image_raw FAILS Super confused, help

rdhn gravatar imagerdhn ( 2015-03-10 04:44:32 -0500 )edit

Can you provide your "rostopic list" command output and "rosnode info image_proc" command output? Those should answer what is going wrong.

Valts gravatar imageValts ( 2015-03-10 20:05:17 -0500 )edit

continued as a new question [how to use image_proc node to process images]

rdhn gravatar imagerdhn ( 2015-03-11 07:06:01 -0500 )edit

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Asked: 2015-03-10 01:14:22 -0500

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Last updated: Mar 10 '15