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I`m running one ground processing PC called snake. and another computer on Robot call UAV. Communication works fine. I can run hokuyo node on UAV and see the data on the data by using rostopic echo in PC snake

Problem is when I launch the laser scan matcher and Gmapping using launch file on PC snake. I can see laser on RVIZ by selecing /laser frame. but I can`t see the map at all.
After connect laser to PC snake and run hokuyo and mapping launchfile. It works fine

my launch file is

And there is no error at all but

MessageFilter says that MessageFilter : Dropped 100.00% of messages so far. Please turn the [ros.gmapping.message_notifier] rosconsole logger to DEBUG for more information.

the map doesn`t comes out

any idea why?

Originally posted by snakehaihai on ROS Answers with karma: 28 on 2013-02-04

Post score: 1


1 Answer 1


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If multiple machines are involved the first thing to do (see also Network Setup) is always checking

  1. if basic communication works between them by sending data around on some topic. Seems to work from what you describe
  2. if the clocks of all computers are properly synchronized. This is commonly done using chrony. Some more info can be found here and here. A search on this site will probably also turn up some useful discussion.

To me your issue sounds like it could be related to a time offset between machines.

Originally posted by Stefan Kohlbrecher with karma: 24361 on 2013-02-04

This answer was ACCEPTED on the original site

Post score: 2

Original comments

Comment by snakehaihai on 2013-02-05:\

  1. I can see scan and shift on rviz for different frame on all of my computers. Means wireless network is function fine. Scan and shift of tf can be observed. But only Gmapping is not running. suspect is the 2nd problem you were mentioning

Comment by snakehaihai on 2013-02-05:
Just tested. Ok there are something appears on the screen now. Looks like a map but it`s not published well. there is an error

Comment by snakehaihai on 2013-02-05:
Ok it`s the timing problem. roswtf gives WARNING Received out-of-date/future transforms:

  • receiving transform from [/laser_scan_matcher_node] that differed from ROS time by 16.823852148s

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