simple visualization questions 3D Map

[Alain]

Hi,
First of all, I have started to use RTAB-Map with an L515 to scan small environments and people on Windows10
It seems to be doing what I need very well, although I see on this forum that the typical use would be for much larger maps and for robots (and I am impressed by the possibilities I see).
Said that:
I am completely new to Rtab-Map and LIDAR scanning, and have two very basic questions.
1. On the 3D Map window, while the 3D Map is being constructed, I can see two paths that are drawn on the window. I figured out one of them is the ‘trajectory’, and I can deactivate it from being shown, but I cannot figure out what the other path is, and if I can stop it from being visible on top of the image.
2. When I press the stop button, the software stops responding and it takes quite a while before it starts responding again. I guess this is normal, as it is computing the Map, but was wondering whether there are some settings that will change the time it takes to do this computation.
Hope this makes sense, and that someone can give me some hints,
Thanks,
 Alain.

[matlabbe]

Hi Alain,

In 3D Map view, you would see in white the odometry trajectory, which can be disabled with the right-click menu. The cyan trajectory is the map's graph. To hide it, you should go in Preferences->3D Rendering, scroll way down and uncheck "Show graphs" under Map column.

When you press stop and it looks busy, it is a bug with the realsense driver (sometimes it even makes the application crash...). The application is just waiting that the driver is completely stopped. Depending on the realsense driver version installed, or if you are on Windows or Linux, it may take more time or less, not sure if it is a usb issue.

EDIT: I did some tests with 0.20.16 realease in Windows 10. When enabling Debug level in Logger options, we can see where it is stuck:

[DEBUG] (2022-04-10 21:20:19) CameraRealSense2.cpp:105::rtabmap::CameraRealSense2::close() Closing 3 sensor(s) from device 0...
[DEBUG] (2022-04-10 21:20:41) CameraRealSense2.cpp:126::rtabmap::CameraRealSense2::close() Clearing devices...

We can see it requires 22 seconds on this trial to just close realsense device. In the code here, we can see a comment for Windows, where hardware reset should be done to avoid a freeze in the destructor of the device afterwards. Doing a second time, another 22 seconds to wait on top, third time it passed almost instantly but app crashed 2 seconds afterwards.

cheers,
Mathieu

[Alain]

Hi Matthieu,
Thank you so much for the detailed explanation, it now makes sense.
Have a nice day,
Best
Alain