How to train from scratch or finetuning?

[VillardX]

Thank you for your great work!

In my situations, I want to train dust3r from scratch or finetune it on my own data. You provide the Co3d preprocessed data demo. However I still have some questions.

1. About the depths, is the depth png in milimeters?
2. About the camera parameters(K R T) in ".npz" file. In the "camera_pose.npy", is the R matrix in W2C or in C2W? And is the T vector's unit is the same as "maximum_depth.npy", which means both in milimeters?
3. About the amount of the data. How many train data image pairs can make the training/finetuning realll works? When I train/finetune it on my own data, the loss becomes smaller than 0. And the effect is far from the raw pretrained model you provided. Is it reasonable?

Hope for help, thanks.