Regarding the 2 dimensions of the Optical Flow

Hi, I have a question regarding the explanation of the optical flow used. The git page states,

`We only use the first two output dimensions, and apply the same cropping as for RGB. The provided .npy file thus has shape (1, num_frames, 224, 224, 2)`

However, I was wondering what this is referring to exactly. Is this the stack of `u` and `v`, the output of the TVL1?(if that is the case, just wondering in what order?) Or do you make it into a rgb image and use just the rg ?

This was a little unclear for me, thanks.