How to calculate location x and y between current frame and loop closure frame

[kokeliang]

Hello. Thank you for your hard work for lidar loop closure.
I red the paper and the source codes. In the paper it said the position x and y between current frame and loop closure frame could be calculated by lidar iris. But from the source code, i can't find where the location x and y between current frame and loop closure frame are calculated. Could you give me some tips? Thanks a lot.