rosjava/android_core

problem with android_tutorial_image_transport

Closed this issue · 6 comments

hungbui-io commented

Hey guys,

I'm playing with the android_tutorial_image_transport. I want to show the images from rosbag file on an android device by changing the topic name: image.setTopicName("/tango/camera/color_1/image_rect/compressed"); but it did not show anything. Why is that? Am I missing something?
Any helps would be much appreciated!

adamantivm commented

@hungbv11 as far as I know it should work. Some ideas to orient debugging:

  • Perhaps the problem is that the app is not using the time topic from the bag?
  • Perhaps there is a networking issue between the nodes (try to set ROS_IP on the host with the bag before launching the bag reading process)
  • 👍1
hungbui-io commented

@adamantivm Thanks a lot for your reply

  • For time synchronization, I set the /use_sim_time to true and play the bag file with --clock but the app still didn't show anything.
  • For the networking issue, I don't quite understand what you means. I did test the android_camera_tutorial and it worked fine without error.
    Here are the rqt_graph of the nodes
    screenshot from 2017-07-04 11 47 28
adamantivm commented

@hungbv11 I am sorry I can't tell what could be wrong with that information.
One other suggestion that comes to mind is to try display the image from a live topic instead of a bag file to see if that makes any difference.

hungbui-io commented

I wrote a simple node publishing images from laptop webcam but the android app did not subscribe anything :(

jubeira commented

Hi @hungbv11,
I'd start by adding more logs to see what's happening exactly.
I would try to avoid simulated clock times at the beginning to discard sources of error (see rosjava/rosjava_core#148).

Perhaps as you say this is not the problem, but just for a reference about networking: http://wiki.ros.org/ROS/Technical%20Overview. It is explained there that all the nodes should be able to resolve each other's address/ name, and setting the variable ROS_IP in the linux side fixes that in some cases.

hungbui-io commented

Hey @adamantivm,
I fixed the bug. I forgot to add "export ROS_IP" to the .bashrc file. Here is the the solution for my problem
Anyway, I really appreciate your help!
Cheers