Rosanswers logo

ROS Kinetic - Ubuntu 16.04


An app I can't control outputs data on the /point_cloud topic.

A Laser_scan_matcher node can accept pointcloud data on the /cloud topic, and can output /PoseStamped topic.

What I'm doing

I made a launch file which contains:


   <remap from="tango/point_cloud" to="cloud"/>

   <node pkg="laser_scan_matcher" type="laser_scan_matcher_node" 
    <param name="use_cloud_input" value="true"/>
    <param name="publish_pose_stamped" value="true"/>
    <param name="use_imu" value="false"/>
    <param name="use_vel" value="false"/>
    <param name="use_odom" value="false"/>

(This is for live output - not bagfiles.)

Normally, rqt_graph looks something like:

(app) --> [/cloud] --> (laser_scan_matcher_node) --> [/PoseStamped]

What I'm getting

Instead it looks like this:

image description

What am I missing?

Originally posted by anonymous32749 on ROS Answers with karma: 62 on 2018-04-16

Post score: 0

Original comments

Comment by Delb on 2018-04-16:
I'm not sure about it but maybe you should write <remap from="cloud" to="tango/point_cloud"/> if you do the remapping in this launch file or write <remap from="tango/point_cloud" to="cloud"/> in the launch file that launch your app.

Comment by anonymous32749 on 2018-04-16:
@Delb remapping from "cloud" to "tango/point_cloud" worked, funnily enough! Instead of the node using the /cloud input, it started using /point_cloud as input. Thanks!

Comment by Delb on 2018-04-16:
When you do <remap from="x" to="y"/> you ask a node to change its input/output topic x to a topic y so when you had your issue you were asking the node to change an unknown input topic which is why it didn't worked. (So I think my other solution would have worked too)

Comment by anonymous32749 on 2018-04-16:
@Delb But as I said, I can't control the source node. I can't specify that it has to output to /cloud. I can only edit the launch file of the Laser Scan Matcher node.

Comment by Delb on 2018-04-16:
Oh yes I ommited that sorry. (You should now mark your question as closed since the problem is solved)

Comment by gvdhoorn on 2018-04-16:\

You should now mark your question as closed since the problem is solved

Please don't do that.

@OperationCrossbow: please post what you ended up using that solved your question as an answer. Then accept your own answer.

We tend to not close questions here on ROS Answers. We mark them answered.

Comment by anonymous32749 on 2018-04-18:
@gvdhoorn It says "You should now mark your question as closed since the problem is solved" above your comment. I'm getting conflicting information here. Also, ROS Answers tells me I have insufficient points to accept my own answer.

Comment by gvdhoorn on 2018-04-18:
@OperationCrossbow: @Delb may not be aware of this 'policy'. I did not make this up myself, I'm just passing along what I've observed over the past 5 years (yes, that is a logical fallacy) and has worked well.

An answered question is clearly visible as such: it gets a checkmark. A closed ..

Comment by gvdhoorn on 2018-04-18:
.. question only shows [ closed ] in the question list, but it's unclear as to why it was closed.

Finally: answered is some form of closure, but closing does not always mean answering.

Comment by Delb on 2018-04-18:
Yes I'm sorry I thought it was the right thing to do, my apologies.

Comment by gvdhoorn on 2018-04-18:
No problem.

Comment by anonymous32749 on 2018-04-18:
@gvdhoorn I also lack sufficient 'points' to reopen other past questions I've closed. Will keep questions open in future, though.


1 Answer 1


Rosanswers logo

I ended up using <remap from="cloud" to="tango/point_cloud"/> instead.

Instead of /point_cloud changing into /cloud and the node accepting this as input, it changed the node to accept /point_cloud directly. It serves me in my goal, so this work-around is good enough.

Originally posted by anonymous32749 with karma: 62 on 2018-04-18

This answer was ACCEPTED on the original site

Post score: 0


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.