SLAM with D435i tutorial： how to evaluate the localization accuracy？

[ClarkWang1214]

I am new to VSLAM. I am following the instructions of "SLAM with D435i tutorial"
roslaunch realsense2_camera opensource_tracking.launch,

I have got the 2D occupancy map of my office successfully.

As you said，”As result of comparision, error of the data is just few centimeters“

I want to know how to evaluate the localization accuracy without any GroundTruth? Could you give some suggestion？

Thx.