Anchor to ground truth

[murmur]

Hi,
In desktop version i found the option to anchor clouds to ground truth. However, when I open a database (Tango), the option is still inactive. How does it work? Is there some documentation/tutorial?
Thanks.

[matlabbe]

Hi,

That option is enabled only if the database contains a ground truth recorded while mapping. Tango App doesn't record any ground truth. This option exists only for convenience when processing SLAM datasets having ground truth to compare visually the ground truth map and the map created by SLAM.

cheers,
Mathieu

[murmur]

Thanks.
Is there any chance that ground truth will be applicable for Tango?

Julian

[matlabbe]

Hi Julian,

We would require an external global positioning system (like a VICON or HTC Vive's tracker) to do this, interfacing it with android so that we can get information on the phone, then synchronize timestamps between Tango and the global positioning system to record the ground truth poses in RTAB-Map's database.

cheers,
Mathieu

[murmur]

Some kind of georeferencing would be very nice indeed. Actually, we are conducting some tests of Tango trajectory accuracy under GPS-adverse conditions (e.g. http://doi.org/10.13140/RG.2.2.27173.81124) and even "offline" georeferencing with application of firm ground truth (total station based) is complicated without absolute timestamps.
Mathieu, thank you for your work, the range of problems you solve and the quality of support is unprecedented.
Julian

[matlabbe]

Hi Julian,

Thx for the link, very interesting. Adding GPS (or global pose with higher variance) to map optimization has been discussed here, then an experimental implementation has been done here (not tested with GPS though). As the phab2pro or Zenfone can map outdoor (even at direct sunlight), it would make sense to record GPS data along the model (as an option for privacy issue and battery saving).  I opened an issue here!

cheers,
Mathieu

[murmur]

That's great!
Even timestamps would be very appreciated (although I'm not sure whether device time or GPS time, perhaps device...). Regarding GPS, please consider BT receivers support; this would partially solve battery and accuracy issues (as particularly the Lenovo P2P internal GPS seems to perform quite unreliable)
Regards,
Julian