how to identify that GPS has affected rtabmap localization?!

[Masoumeh]

Hi Mattieu,

I have an RTK-GPS, (so expected to have a accuracy of 2cm). I have added this to rtabmap, Now How can i identify that it has made rtabmap localization better? or how can i identify the impact of GPS after adding to rtabmap?
I want to compare before and after adding GPS?
How can i do this?

Thanks

[brown7]

RTABMap (Real Time Appearance Based Mapping) is a SLAM method based on RGBD, stereo and LIDAR graphics, based on an appearance incremental loop detector. The closed-loop detector uses a set of words to determine the likelihood that the new image comes from the old location or the new location. If the closed-loop assumption is accepted, a new constraint is added to the map, and then the map optimizer minimizes errors in the map. The memory management method is used to limit the number of locations used to detect closed loops and optimize graphics. RTABMap can be used alone with a handheld Kinect, stereo camera or 3D lidar for 6DoF mapping, or with a robot equipped with a laser rangefinder for 3DoF mapping.

[matlabbe]

There is a /gps/fix input topic to rtabmap node. To use GPS in graph optimization, you have to set Optimizer/PriorsIgnored to false. You may check this post and this post that show how GPS and SLAM trajectories can be visualized in rtabmap-databaseViewer.

About more robust loop closure detection using GPS, see this page: https://github.com/introlab/rtabmap/wiki/Robust-Graph-Optimization#multi-session