Why is the translation/rotation error recalculated at every 10th frame?

[olibd]

I've been going through the code and I've been having a hard time understanding why the translation/rotation error recalculated at every 10th frame.

at line 191: https://github.com/Huangying-Zhan/kitti-odom-eval/blob/4b850b0815dcd28edef893ca3422125b04a02397/kitti_odometry.py#L191

Why is first_frame resetted at every 10th frame and the whole errors recomputed for a segment (100m, 200m, etc.) We end up with multiple error values for segments of decreasing lengths. It looks like some sort of sliding window of varying length that is moved along the sequence.

Why is it computed this way and not computed over the first 100 meters, then 200 meters, etc?

[thohemp]

This might help: http://www.cvlibs.net/datasets/kitti/eval_odometry.php