RTAB-Map GUI Save Database Problem

[seanxu112]

Hi,

I am currently trying out the optimization option with this link, https://github.com/introlab/rtabmap/wiki/Robust-Graph-Optimization

I only have g2o. I have installed GTSAM, but RTAB-map cannot find the path to it.

The map with Robust optimization looks good. However, I did it in rtabmap GUI, just like the example in the link (source from database). I do not know how to save the optimized point. Should I just map with the params set in the launch file?

Also, is there any way to improve the point cloud map after robust optimization?

Lastly, grid_map (with lidar) from RTAB-map seem to be very sparse compared to gmapping. Is it possible to combine the 2d map from gmapping and point cloud from RTAB-map?

Sincerely,
Sean

[matlabbe]

Hi Sean,

To use GTSAM, rtabmap should be rebuilt (see cmake status). Latest GTSAM >=4 should be also used.

Yes, you can set the parameters in the launch file like shown in the tutorial:

<node name="rtabmap" pkg="rtabmap_ros" type="rtabmap">
   <param name="RGBD/OptimizeStrategy" type="string" value="1"/> <!-- g2o=1, GTSAM=2 -->
   <param name="RGBD/OptimizeRobust" type="string" value="true"/>
   <param name="RGBD/OptimizeMaxError" type="string" value="0"/> <!-- should be 0 if RGBD/OptimizeRobust is true -->
   ...
</node>

What kind of improvements do you want to do on the point cloud map after optimization?

The occupancy grid should be similar between RTAB-Map and GMapping, can you show an example? If it is because of the range of the local occupancy grid, you can set Grid/RangeMax to 0 (default 5 meters).

cheers,
Mathieu

[seanxu112]

Sorry for not replying for this long. I was caught up by something else.

This image is from Gmapping



This image is from RTAB-map. Now I am wondering if it is just probability threshold parameter along with max distance?

Also, if the environment change a bit, do I always need to restart mapping? Or load a previous session can fix the old database?

[matlabbe]

Hi,

What the parameters did you use for rtabmap, is scan matching enabled
(RGBD/NeighborLinkRefining=true)? The maps between gmapping and rtabmap
should be very similar. Please look at this example
for 2D lidar SLAM.

If the environment changed, you can restart rtabmap in mapping mode using
the old database (without --delete_db_on_start!). Set
Rtabmap/StartNewMapOnLoopClosure=true to make sure that you are localized
in the old map before overwriting it.

cheers,
Mathieu