what is the puerpose of depth0[:, 0, :] = 0?

[Asherchi]

in training file, megadepth_warper file, the following is code:
`@torch.no_grad()
def warp_kpts(kpts0, depth0, depth1, T_0to1, K0, K1):
kpts0_long = kpts0.round().long().clip(0, 2000-1)

       depth0[:, 0, :] = 0 ; depth1[:, 0, :] = 0 
       depth0[:, :, 0] = 0 ; depth1[:, :, 0] = 0 `

i want to know that what is purpose of depth0[:, 0, :] = 0 and depth0[:, :, 0] = 0 ?