>>213088539
>>213088608
>>213088615
I don't know how they actually did it, but if I had to fake this without watching any production footage, I'd do two shots:
first with a vertical ladder at a 45 degree slope downward, so you could still climb down it and can still nevertheless stand up upon dismounting it, and you'd be standing at a 45 degree angle. The camera would be on a medal rack to hold it up, rotated at about a 90 degree angle.
You have the actor walk up down the hill, then up the opposite hill till he's occluded by the central column. As they cross about 90 degrees of the room, they're always being able to stand.
You composite the first shot parent-trap style with a second shot, which runs continuously throughout the first shot. You put this shot on the left side of the occlusion center column, and to film it you put the camera shot vertically above from a crane at the top of a similar doughnut.
The first shot ends when the actor walks behind the column, and the second shot has the actor enter frame at an appropriate cue so it looks like they walked from one side of the doughnut to the other: giving the illusion that two shots are one.
Total cost would be two half doughnut sets, a camera crane that supports rotation and significant height as needed, and the editor to composite the two shots.
