Confused about the cam2world pose

[CavalloneChen]

Thank you for your excellent work!
There are files named 'frameID.txt' and 'frameID_camID.txt' under the 'ego_pose' folder. I don't understand what are the meanings of 'frameID_camID.txt'.

This is what confused me:

1. It seems that 'frameID.txt' is ego2world, and 'frameID_camID.txt' are cam2world transformation matrices of corresponding frames. Is it correct?

2. In script 'lib/utils/waymo_utils.py', what does the variable 'c2w' mean exactly? pose = ego_cam_poses[cam, frame]; c2w = pose @ ext I assume 'ext' is cam2ego. But what does 'ego_cam_poses' (read from 'ego_pose/frameID_camID.txt') mean? And why not use 'ego_frame_poses' from 'ego_pose/frameID.txt'?

[Within-yao]

It confused me too.

[Shelfcol]

I treat frameID.txt and frameID_camID.txt all as Twv, and multi cmera rendering results seems good

[Hanxuan411]

It confused me too.

[Golden-Pigeon]

It confused me too. Hope @zju3dv would answer this question!