Question about building's shadow

[wolkenwand]

Hi, i try to make shadow in drydock structure to not following the land contour, so the shadow will fixed on normal postion like in flatland.
Is there anyway to do this? i edit the file using nifskope, my guess is i must edit the "SHADOW" branch in drydock.nif but i don't know which one to edit or remove.
Thanks for any help.