AV101 In order to see anything in the front of your meeting room it must be at least 5 feet 4 inches above the floor.
Try it. Have someone sit in front of you in any meeting room, regardless of room size.
What can you see over the head of the friend between you and the screen in the room? NOTHING below 5'4"!
If this is the case how big a screen can be seen in a room with a 9' ceiling? (Hint: 9' minus 5 feet)
If you don't use the screen top valence and place the screen at its highest, the useful screen height is only 4 feet.
That looks like a mistake in an empty room before the audience sits down, but the fact is, anything below that feet is wasted so don't expect the attendees to see material below that. I have seen 8' tall screens placed in a 9' ceiling breakout room. When asked, the hotel AV tech said, "They wanted the largest screen possible."
Now the question is how many people can read what is on a 4' high screen? Using the legibility formula (FV = 8x H) anyone further than 28' from the screen will not be able to read typical detail.
If you follow my previous posts you will see a recurring theme: ceiling height = legibility.