Remapping topics in gazebo nodes

[jaredmoore]

I'm currently troubleshooting a problem with remapping the clock topic in a gazebo node. A detailed explanation of the problem is here: http://answers.ros.org/question/242656/is-it-possible-to-remap-clock/

A synopsis is the following. Ros Kinectic/Gazebo7. Using <remap> either at launch file level, or within the <node> tags launching gzserver is failing. Running it on a Ros Indigo/Gazebo2 VM allows the code to work. Has there been a change to the remapping policy, solely within the gazebo nodes for this package?

gazebo_only.launch:

<launch>

<!-- ********************* Begin Gazebo Defaults ******************************** -->

  <!-- these are the arguments you can pass this launch file, for example paused:=true -->
  <arg name="args" default="--verbose -r -e ode"/>
  <arg name="world" value="worlds/empty.world"/>

  <!-- set use_sim_time flag -->
  <!--<param name="/use_sim_time" value="true" />-->


<!-- ********************* End Gazebo Defaults ******************************** -->    


  <!-- start gazebo server-->
  <!--<env name="GAZEBO_MASTER_URI" value="http://localhost:11345"/>-->
  <node name="gazebo" pkg="gazebo_ros" type="gzserver" args="$(arg world) $(arg args)" respawn="false" output="screen">
    <remap from="rosout" to="rosout_remapped" />  
    <remap from="clock" to="clock_remapped" />
  </node>

</launch>

Test with:

1. roslaunch gazebo_only.launch
2. Open another terminal
3. source devel/setup.sh
4. rostopic list

Expected output:

/clock should be remapped to /clock_remapped and /rosout should be remapped to /rosout_remapped.

On my Kinectic/Gazebo7 VM this does not work correctly, but on an Indigo/Gazebo2 VM it does properly remap the topics. Adding other nodes in either version gives them the remapped topics, but Gazebo still remains mapped to the /clock topic.

[anthonyjclark]

I've experienced the same issue, and I've not found a way around it yet. Anyone track down the change that causes this failure?

[j-rivero]

Umm interesting. Have you tried to do the same with any other node different that Gazebo? Is that working?

[jaredmoore]

Yes, strangely enough if I spool up many different nodes, it is only the Gazebo node that fails to remap. I can provide more code or a different example if needed.

[jonbinney]

This commit in the kinetic-devel branch looks suspicious: a90e609

[jonbinney]

Here's the corresponding PR: #387

Sounds like remappings were intentionally removed; @scpeters @peci1

Seems to me that when run through roslaunch/rosrun, remappings should be used.

[j-rivero]

Thanks John for the commenting here. @jaredmoore the fix is now if the kinetic-devel branch, could you please check if that fixes your problem?

[jaredmoore]

Sure thing, it might be a week or two as I'm in the middle of finals, but I will try and set some time aside. Thanks for the digging on this!

[jaredmoore]

I tested this on my installation after removing the apt-get acquired ros-gazebo-pkgs and building from the source on the devel branch. The fix appears to work correctly and I am now able to remap the Gazebo topic. It will be a few weeks before I can test it on my larger instance, but for now I am confident that this addresses the issue. Thank you all for your help!