Warning "RtabmapThread.cpp:575::addData() Data buffer is full, the oldest data is removed to add the new one."

[jendzi]

Hi, I wrote my own camera grabber that constructs rtabmap::SensorData and posts it in rtabmap::CameraEvent. SLAM seems to work fine, pointcloud looks reasonable too.

However I started seeing the error

RtabmapThread.cpp:575::addData() Data buffer is full, the oldest data is removed to add the new one.

Is this concerning? Could it mean that rtabmap cannot process data in time and it start accumulating? If so, should I look into lowering the framerate and resolution?

Thanks,
Jenna

[matlabbe]

What frame rate did you set? If you use 1 Hz by default, that warning would show if RTAB-Map cannot process the previous frame under 2 seconds. For example, the thread received at least more 2 frames (2 seconds) while RTAB-Map is still processing the previous one, so the buffered frame is skipped to put the new frame.

If you set frame rate at 10 Hz and RTAB-Map can only process frames at 200-300 ms, then that warning will be shown often.

jendzi wrote

Could it mean that rtabmap cannot process data in time and it start accumulating?

it is not accumulating, it is skipping a frame. The data buffer size is 1 by default. If you don't see that warning often, I would not be too concerned. It may happens that rtabmap needs to reconstruct the incremental vocabulary to make sure it stays balanced, that could make RTAB-Map spiking in processing time, so that warning may happen at that time. If it is the cause, it should not happen often though. You can show the processing time of rtabmap with:

rtabmap-report Timing/Total/ms rtabmap.db

Here an example (the spikes over 1 sec could cause that warning):