Surprised at some of the responses here.
ICAO Annex 14 - Volume 2
5.2.9.1 A touchdown/positioning marking shall be provided where it is necessary for a helicopter to touch down or be accurately placed in a specific position.
5.2.9.2 A touchdown/positioning marking shall be located so that when the pilot’s seat is over the marking, the undercarriage will be inside the load-bearing area, and all parts of the helicopter will be clear of any obstacle by a safe margin.
The only time that the safety of the helicopter can be guaranteed is when the pilot is positioned correctly on the TD/PM. For those who wish to make their own assessment of obstacle clearance, read the Brent Spar accident report (G-BEWL) & the human factor issues therein