mask = torch.zeros((8,8,2052)) # in this case the depth is 2052, but can be much larger
idxs = tensor of size (29, 3) # the 29 can also be larger - (max is 8 * 8 * depth_of_mask)
for idx in idxs:
  # idx is a tensor of size (1, 3), 
  # using unbind to get each number on its own 
  # and fing the right 'cell' in the mast
  mask[idx.unbind()] = 1