Nothing shows that its angled.
Apart the fact that in the previous chamber shots the officers should be angled.
Otherwise you can notice the viewscreen behind the chamber.
Veers inform vader and vader turns 180 degrees to view the screen. So i assume Veers had his back on the holo chamber .
From what part of the room piet enters to inform vader? We see him step up a level not slowing rising like a ramp.
If that is true then we can assume from the pic that ady posted they remove the chamber for aesthetic/artistic reasons
-Angel