loop-closures though robot is static

[akunin]

Hi,
We noticed that rtabmap running local loop-closures and update pose even when robot is static and smallDisplacement is true.
Odometry indeed has changed a bit (0.0000x values).
What's the reason for it?
Log is below:

[rtabmap-5] [REPORT] (2024-01-29 11:30:03.739) Rtabmap.cpp:1749::process() Last localization pose = xyz=1.976299,0.899696,0.000000 rpy=0.000000,0.000000,-0.480990, closest node=136 (1.714005 m)
[rtabmap-5] [REPORT] (2024-01-29 11:30:03.741) Rtabmap.cpp:2149::process() Highest hypothesis=16, value=0.162588, timeHypothesesCreation=0.000020s
[rtabmap-5] [REPORT] (2024-01-29 11:30:03.820) Rtabmap.cpp:3086::process() loopClosureVisualInliers: 75, loopClosureVisualInliersRatio: 0.039767, loopClosureVisualMatches: 201
[rtabmap-5] [REPORT] (2024-01-29 11:30:03.821) Rtabmap.cpp:3341::process() maxLinearErrorRatio: 0.195929
[rtabmap-5] [REPORT] (2024-01-29 11:30:03.821) Rtabmap.cpp:4043::process() Loop closure detected! Node id 8534 with node id 16
[rtabmap-5] [REPORT] (2024-01-29 11:30:03.826) CoreWrapper.cpp:1564::commonMultiCameraCallbackImpl() Process frame 8306 <<< finished (607.00 ms)
[rtabmap-5] [REPORT] (2024-01-29 11:30:03.827) CoreWrapper.cpp:1282::commonMultiCameraCallbackImpl() Process frame 8307 >>> starting
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.304) Memory.cpp:5483::createSignature() Markers detected = 0
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.328) Rtabmap.cpp:1749::process() Last localization pose = xyz=1.971227,0.898475,0.000000 rpy=0.000000,0.000000,-0.484928, closest node=136 (1.717869 m)
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.329) Rtabmap.cpp:2149::process() Highest hypothesis=16, value=0.159489, timeHypothesesCreation=0.000018s
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.399) Rtabmap.cpp:3086::process() loopClosureVisualInliers: 74, loopClosureVisualInliersRatio: 0.039764, loopClosureVisualMatches: 190
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.400) Rtabmap.cpp:3341::process() maxLinearErrorRatio: 0.209175
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.401) Rtabmap.cpp:4043::process() Loop closure detected! Node id 8535 with node id 16
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.406) CoreWrapper.cpp:1564::commonMultiCameraCallbackImpl() Process frame 8307 <<< finished (579.00 ms)
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.407) CoreWrapper.cpp:1282::commonMultiCameraCallbackImpl() Process frame 8308 >>> starting
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.873) Memory.cpp:5483::createSignature() Markers detected = 0
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.902) Rtabmap.cpp:1749::process() Last localization pose = xyz=1.978642,0.893781,0.000000 rpy=0.000000,0.000000,-0.470291, closest node=136 (1.717591 m)
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.904) Rtabmap.cpp:2149::process() Highest hypothesis=16, value=0.159171, timeHypothesesCreation=0.000021s
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.984) Rtabmap.cpp:3086::process() loopClosureVisualInliers: 65, loopClosureVisualInliersRatio: 0.034704, loopClosureVisualMatches: 211
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.985) Rtabmap.cpp:3341::process() maxLinearErrorRatio: 0.154534
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.986) Rtabmap.cpp:4043::process() Loop closure detected! Node id 8536 with node id 16
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.990) CoreWrapper.cpp:1564::commonMultiCameraCallbackImpl() Process frame 8308 <<< finished (583.00 ms)
[rtabmap-5] [REPORT] (2024-01-29 11:30:04.993) CoreWrapper.cpp:1282::commonMultiCameraCallbackImpl() Process frame 8309 >>> starting

[matlabbe]

Is it in localization mode?

The small displacement may be ignored in localization mode. In mapping mode, loop closures can be detected with small displacement only if the previous node doesn't have a loop closure. This check as implemented right now would not work in localization mode as new nodes are always disconnected from previous nodes in the graph. I created an issue about that.

cheers,
Mathieu

[akunin]

yes, it's localization mode. result pose is changing though robot is static

[matlabbe]

It has been implemented in https://github.com/introlab/rtabmap/commit/a11ea291d8391676cf2ddc83f110c89fc237b9e4