Definition of touching the line

As far as I understand it, only the part of the cork of the shuttle that actually makes contact with the ground upon landing, counts when determining whether the shuttle landed in or out. Isn't it impossible to know how much of the cork actually touched the ground? The area of contact is completely dependent on the characteristics (softness, roundness) of that specific shuttle as well as the landing speed. If the cork is rounded and is perfectly rigid and doesn't deform, the area of contact will be microscopic. Wouldn't it just be more practical and fair to just use the centerpoint of the cork to determine in/out?