The placement of the cinema screen is precisely calculated for every THX Certified Cinema. To ensure the best possible viewing experience, THX recommends having a 36 degree viewing angle from the farthest seat in the auditorium.
Prior to construction, THX advises cinema designers and architects to accommodate for the 36 degree horizontal viewing angle. And, to make sure that every seat has an unobstructed view, THX often recommends either elevating or lowering the entire floor to adjust the seating location.
Click here, for THX viewing angle recommendations for home theater screens and HDTVs.