I would say that all popularised 3D film technologies would be more accurately described as two and a half D. It’ll be a while before we’ll be editing “film in the round.” However, until then, my friend Jean has sent me an interesting document from IMAX on what to bear in mind when editing IMAX 3D (the IMAX format is known as ’15/70′):
Some editors screen all the footage in 35mm, sitting very close to the screen and concentrating hard — a demanding method, as the two formats look radically different. If something looks questionable, they order a 70mm print of that footage. Some print and screen their rough cut in 15/70. But, as Andy Gellis has observed, “If the film is working well on the Avid, then it will work like gangbusters on the big screen, as long as you calculate or calibrate the shot durations correctly. The brain can’t absorb the overload of information on the IMAX screen as readily as it can on the video monitor.”
Video will not give you an adequate impression of how the footage will look on the giant screen. For instance, if the eye has to move too far across the scene, a cut won’t work as well. Or in 3D, if the depth cues in successive shots aren’t similar then the brain will have difficulty fusing the left eye and right eye images. You may not recognize a spectacular 15/70 shot when seen in video. For these reasons, some video editors will rely more heavily on their 35mm printdowns, and selective contact printing of 70mm footage.
Occasionally, the reverse may be true. Stephen Low finds that “when you need to bamboozle the audience for a second to make a cut work and there’s something distracting on the edge, sometimes 15/70 is more forgiving than small formats, because (in 2D) you’re not as aware of the edges. A bad cut in 35mm or on video may be all right for the giant screen because peripheral vision is nowhere near as important, and the audience is more focused on the centre. And in IMAX Dome theatres, you’re not at all aware of the edge of the screen.”
Notes editor Barb Kerr: “You have to be even kinder to the audience in 3D, because their eyes are really focused deeply inside the picture. If you change the focal plane to something essentially above the head of the person in front of them in the theatre, you have to set them up to make that shift or it can be completely baffling or hurt them.”
From The 15/70 Filmmaker’s Manual from the IMAX site