RTAB-MAP with only 3D LIDAR and no loop closing

[Amber]

Hi Mathieu,

I recently started using RTAB-MAP with ROS support with v0.20.9-melodic. My first issue is that when I run in the mapping mode, it does not use the Bayes filter to update the nodes. I created a few checkpoints to print, but they do not print because,  signature->isBadSignature()is not set false ever.

The loop closure is never detected and shows just like the one in the below image.

Following is the shared launch file that I am using.
https://drive.google.com/file/d/1DUIEUCgC8esZIaxRVT56EG0a4F-BmfUQ/view?usp=sharing

I also need your suggestion if this launch file is fine to get the desired results. If not, kindly suggest changes.

[matlabbe]

Hi,

With lidar-only, the Bayes filter is not used (it is just for visual loop closure deteciton). There is no global LiDAR-based loop closure detection built-in in rtabmap, you may check this project: https://github.com/MarvinStuede/cmr_lidarloop

However, if odometry is not drifting too much, Proximity Detection could be triggered with only lidar. Do you have a database to share to see why procimity detections have not been detected?

cheers,
Mathieu

[Amber]

Hi Matheu,

As you suggested, I tried implementing <nabble_embed>cmr_lidarloop</nabble_embed> with <nabble_embed>RTAB-Map</nabble_embed>. Separately, I performed with RTAB-MAP mapping without cmr_lidarloop in a gazebo simulation.  Please find the .db file in the link nelow.

https://drive.google.com/file/d/1wrd0N7lEhMyoRMBxDwzyQ79Lk2Avhqdx/view?usp=sharing

Also, let me know if you need the bag file. Additionally, I found that /rtabmap/MapData, /rtabmap/MapGraph, and /rtabmap/info are not publishing when only the LIDAR is used. Particularly,  /rtabmap/MapData is required while using cmr_lidarloop package.

Also, I saw that cmr_localization package which is linked with cmr_lidarloop uses RGBD and RGB cameras. Do they work without the cameras also? I am unable to publish scan_descriptor topic actually, while following the documentation of the cmr_lidarloop. The corresponding issues have been posted in the link below.
https://github.com/MarvinStuede/cmr_lidarloop/issues/4

Please let me know your views and suggestions to resolve it.

thank you,

Best,
Anindya

[matlabbe]

Hi, if mapData is not published, this means rtabmap is doing nothing. Do you have warnings in terminal telling that rtabmap didn't receive topics for 5 seconds?

The cmr_lidarloop package should work without camera. On their system, they had cameras that were also fed to rtabmap, but external cmr_lidarloop only needed the scan_descriptor fed to rtabmap node and extracted back from mapData.

cheers,
Mathieu

[Amber]

Hi Matheu,

thank you for your response. I tried many bags over the last two weeks and got the mapdata publishing and cmr_lidarloop detecting loop closures with lidar only. However, to verify things are working I want to check if there is/are matching loop closures obtained using camera data (RTAB-Map) and lidar data (using cmr_lidarloop). While I set subscribe_scan_descriptor (true), can I keep subscribe_rgbd (true) at the same time? Can I identify these two kinds of loop closures distinctively in rtabmapviz?

warm regards,

[matlabbe]

Hi,

Yes, you can subscribe to both topics at the same time.

To distinguish loop closure types, we can set a type in Link msg:
https://github.com/introlab/rtabmap_ros/blob/2c144400ed496e5de6cca36b228e75f9a2d0b47f/msg/Link.msg#L12

In cmr_lidarloop, the link will have a type Link::kUserClosure: https://github.com/MarvinStuede/cmr_lidarloop/blob/39b44c1b4fe203fa89319820f25b12d428dfabe2/src/lidar_loopdetection.cpp#L291

Loop closures detected with camera will appear as Link::GlobalClosure, all types are there: https://github.com/introlab/rtabmap/blob/aee034c5ed9d1909a976d1d4bb1a849eb26e1991/corelib/include/rtabmap/core/Link.h#L41-L56

In rtabmapviz, open Graph View, each kind of links can have a different color. Right-click on Graph-View panel to change them.

cheers,
Mathieu

[Amber]

Hi Matheu,

I still find issues related to subscribing rgbd_image and scan_descriptor simultaneously for cmr_lidarloop. Can you please check the attached launch files that I am using and help understanding if there is any problem with the same.

camera_lidar.launch
cmr_lidarloop.launch

[matlabbe]

Hi, you should set subscribe_rgbd to true to subscribe to rgbd_image. However, you are right, there was a bug when subscribing to scan_descriptor at the same time. I fixed the issue in this commit.

And for all the paramters not found warnings from rtabmapviz, either set rtabmap node name to "rtabmap" instead of "rtabmap_mapping" or add

<param name="rtabmap"     type="string"    value="rtabmap_mapping"/>

under rtabmapviz node.

cheers,
Mathieu

[Amber]

Hi Matheu,

It is not working in my system. When I launch the save_detector_data.launch, I get the following error.

[FATAL] [1638968435.476764729]: ASSERTION FAILED
        file = /home/drive/cmr_ws/src/cmr_lidarloop/src/save_data_for_detector.cpp
        line = 136
        cond = s.globalDescriptors().size() == 1

[cmr_lidarloop/save_data_for_detector-2] process has died [pid 4924, exit code -5, cmd /home/drive/cmr_ws/devel/lib/cmr_lidarloop/save_data_for_detector __name:=save_data_for_detector __log:=/home/drive/.ros/log/cc9515da-5826-11ec-a9b4-9c5c8e6e5977/cmr_lidarloop-save_data_for_detector-2.log].
log file: /home/drive/.ros/log/cc9515da-5826-11ec-a9b4-9c5c8e6e5977/cmr_lidarloop-save_data_for_detector-2*.log

Also, s.globalDescriptors().size() becomes zero my simulation. I have put

 
 <remap from="rgbd_image"       to="/rgbd_image/compressed"/>
 apart from setting  subscribe_scan_descriptor=true.

Please note that I am using rtabmap-0.20.7 version at present. I also made the changes that you committed in the above response.

Best,

[matlabbe]

I will have to make a configuration example to try to reproduce the problem. I'll come back later.

[matlabbe]

Hi,

I was able to make cmr_lidarloop working with latest rtabmap version in this post:
 https://github.com/MarvinStuede/cmr_lidarloop/issues/5#issuecomment-991984033

For your specific question on cmr_lidarloop, I think it is better you continue with your post on their github:
https://github.com/MarvinStuede/cmr_lidarloop/issues/4#issuecomment-989714608

[Amber]

Hi Matheu,

Thank you for your response. Do you mean that you tried for both the RGBD and the LIDAR data? I am already able to use it for LIDAR only case. Anyways, I'll follow up on the Github issue that I had created.