[Docs] Problems on Waymo 3d Box

[Wang0203]

Branch

main branch https://mmdetection3d.readthedocs.io/en/latest/

📚 The doc issue

Hello, I am confused on the waymo_infos_val.pkl information (bbox 3d). Why is the z-coordinate -24, did it go underground?

Suggest a potential alternative/fix

No response

[VeeranajenyuluT]

waymo coordinate system is same as kitti dataset which is camera coordinate system, plz refer to this document https://mmdetection3d.readthedocs.io/en/latest/user_guides/coord_sys_tutorial.html. So if that is the case, i believe Z points to downwards which is in -ve. They suggests that it needs to be converted to Lidar coordinate system.