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gmapping: "Skipping XML Document..."

asked 2017-11-02 18:42:38 -0500

Rick Armstrong gravatar image

updated 2017-11-28 19:54:51 -0500

Firing up an instance of pointcloud_to_laserscan_node (not the nodelet) on Indigo + Ubuntu gets

[ERROR] [1509665358.223587616]: Skipping XML Document "/opt/ros/indigo/share/gmapping/nodelet_plugins.xml" which had no Root Element.  This likely means the XML is malformed or missing.

Two questions:

  1. Why would pointcloud_to_laserscan be looking for a file in slam_gmapping?
  2. Can we safely ignore this?
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May I suggest a topic title change? The error message specifically states that /opt/ros/../gmapping/nodelet_plugins.xml has a problem. pointcloud_to_laserscan is not mentioned anywhere.

gvdhoorn gravatar image gvdhoorn  ( 2017-11-03 00:39:18 -0500 )edit

Just saw this comment. Done.

Rick Armstrong gravatar image Rick Armstrong  ( 2017-11-28 19:55:30 -0500 )edit

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answered 2017-11-03 00:24:36 -0500

gvdhoorn gravatar image

updated 2018-01-27 04:35:47 -0500

update: PR#56 was merged, new version of gmapping is in the shadow repository and should be available in the regular repositories after the next sync.

This is probably ros-perception/slam_gmapping#55.

Can you verify there is a nodelet_plugins.xml in the /opt/ros/indigo/share/gmapping directory?

If not, that is the cause. The CMakeLists.txt is not install(..)ing that file (at least in the current version), which makes things work in a devel space, but not in an install space. As the binary pkgs contain only install(..)ed artefacts, nodelet_plugins.xml is missing from those.

This seems to have been introduced in ros-perception/slam_gmapping#41, which added the nodelet version of gmapping.

Why would pointcloud_to_laserscan be looking for a file in slam_gmapping?

it isn't. It looks that way, but in reality the rospkg plugin infrastructure is just iterating over all ROS pkgs it knows and trying to load the nodelet_plugins.xml file that gmapping has listed in its package manifest.

You just happen to be starting pointcloud_to_laserscan.

Can we safely ignore this?

Yes. If you're not intending to use the nodelet version of gmapping, you should be fine.

Edit: I've submitted a PR to fix this: ros-perception/slam_gmapping#56. Note that gmapping will have to go through a full release cycle before the binaries on the repositories contain this fix.

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Asked: 2017-11-02 18:42:38 -0500

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Last updated: Jan 27 '18