Demo hector_mapping

[viniciusbs]

Hi,

I've been having some problems in building a 3D map without a regular odometry source, using only the rgbd camera and lidars. So, I decided to do a sanity check following the exact steps described in the equivalent tutorial, here. But I'm still facing errors:

At first, everything seems to go smooth:


But around 150s on the bag, when the first (and only I think) loop closure is detected, this happens:


In the end, the map looks like this:


Can someone try and see if you can reproduce the problem? Or is it something wrong with my setup (Ubuntu 16 and ros Kinetic)? Funny thing is that I had no problems when running demo_robot_mapping.launch...

Thanks in advance,
  Vinicius

[matlabbe]

Hi,

The parameters have been updated in the demo_hector_mapping.launch file. What you see is a wrong loop closure accepted because the covariances set in hector's odometry are not compatible with rtabmap. Without updating to latest rtabmap_ros version, you can add those lines under rtabmap node:

<!-- As hector doesn't provide compatible covariance in the odometry topic, don't use the topic and fix the covariance -->
<param if="$(arg hector)" name="odom_frame_id"            type="string" value="hector_map"/>
<param if="$(arg hector)" name="odom_tf_linear_variance"  type="double" value="0.0005"/>
<param if="$(arg hector)" name="odom_tf_angular_variance" type="double" value="0.0005"/>

Loop closures causing such deformation in the graph will be rejected.

EDIT
I was able to reproduce the deformation with the demo_mapping.bag. I updated rtabmap to reject loop closures also causing large wrong rotations in the graph (checking only wrong translations seems not enough in some cases like this one). See https://github.com/introlab/rtabmap/commit/829f05e2fba377f0c2516e0619aa7ecf28814569

cheers,
Mathieu

[viniciusbs]

Hi Mathieu,

Adding the parameters seemed to do the trick for me.

But in any case, I understand it is better to change to the built from source version, instead of the binaries, to get the latest fixes, right?

Thanks a lot again,
  Vinicius

[matlabbe]

Hi,

To get latest bug fixes like the commit above, yes, if you don't mind rebuilding rtabmap and rtabmap_ros projects (there is a guide here to build both from source).

Note that next week, I'll try to release new ros binaries (the current binaries are 5 months old...).

cheers,
Mathieu