How does d2 deal with the different width and height in a single batch?

As detectron2 uses cfgs such as INPUT.MIN_SIZE_TRAIN INPUT.MIN_SIZE_TRAIN_SAMPLING to randomly resize a single sample, the image size in a batch will differ. How does it form a batch which has same fixed size at H,W dim?

I search the codes and just can't find the point but the transform which does the random resize.

Start with the INPUT.MIN_SIZE_TRAIN and INPUT.MIN_SIZE_TRAIN_SAMPLING configuration and trace the random resize transform into batch construction. The issue mentions no file or test; done means documenting how differently sized samples are combined into a batch with consistent H,W dimensions.

Written by the indexing model from the issue text.