3D video technology has become a lot more mainstream over the last several years. It seems there’s always a 3D movie or two in theaters now. 3D capable televisions have been on the market for a couple years. There are even handheld devices like Nintendo’s 3DS that don’t require glasses for their 3D effects. Yet despite the proliferation of the technology, it seems that the overwhelming majority of film critics, not to mention ordinary moviegoers, prefer traditional 2D screenings. Why is that?

To answer, I think we need to look in part at what films are trying to do as a medium. Like any other storytelling medium, whether books, theater, or whatever, much of a movie’s success depends on its ability to transport the audience into the world of the story. In a general sense, anything that ups immersion is good; anything that reminds the audience that they’re sitting in a theater watching a movie is bad. It’s why theaters have big screens, comfy seats, and surround sound. Because 3D is obviously a visual technology, let’s focus on the screens.

A traditional 2D screen is like your TV or most of the theater screens you’ve ever watched a movie on – any one where you didn’t have to wear special glasses. Just like in real life, objects that are farther away from the camera (or your eye) appear smaller, which your brain then interprets to judge depth. Everything on screen can be thought of as receding to a point “behind” the face of the screen. For a 2D movie, nothing ever appears to be between the audience member and the screen; the screen is the limit of the movie’s world. So we can think of the image like a sideways pyramid. The image expands, so to speak, from the point to the screen to create depth, the base of the pyramid being the screen itself. However, because objects on screen are expanding from a single point, it gives the illusion that at any time the images might burst from the confines of the screen and wholly wash over the viewer. It’s almost like tunnel vision in reverse. Returning to the idea of the sideways pyramid, instead of imagining your head looking at the base of the pyramid, imagine it just inside the pyramid looking at the point. The projected world would be all of your visible reality. A 2D movie image is immersive because it suggests that this could actually happen, that the world of the movie might completely envelop the viewer’s senses.

Now a 3D screen. Let’s begin with the above idea of the sideways pyramid going from the point of recession to the edges of the screen. But in 3D images do not halt at the screen; rather, they appear to come out from the screen and exist between the screen and the audience. At first blush this seems desirable. If our goal is immersion, isn’t actually having images envelop the viewer better than just suggesting it? There’s a problem, though. Let’s say that there are two people on screen, and let’s say that they’re the same height exactly. They are standing side by side in frame such that their heads are at the very top of the image and their feet at the very bottom. Then one takes a step forward. To show depth, one of two things must happen: 1) The camera moves so that the moving person remains framed exactly as before. In this scenario, the other person would appear smaller, no longer being framed in the same way. Or 2) The camera remains steady. In this scenario the person moving appears bigger, and on a 2D screen, since nothing can appear in front of the screen, we might no longer be able to see the moving person’s head and feet. However, if the movie is in 3D we do expect to see the person move in front of the screen, and what’s more, because everything “behind” the screen is shown in full, we expect to still be able to see the entire moving person. But we don’t. We don’t see the head or feet, just like with a 2D screen.

This is because a 3D image is still confined by the size of the screen. That is to say, the screen is the widest point for the image. A 3D image is constrained to a second sideways pyramid, this one in front of the screen rather than behind, and going from the viewer’s eyes to the edges of the screen. Any image perceived to be in front of the screen can only exist in this cone. What this actually achieves is a break in the illusion of the film world, not a deeper immersion into it. If we put the two pyramids together, the one “behind” the screen and the one in “front”, we get a whole three dimensional shape within which exists the entire world of the film. Rather than suggesting a world about to wash over the viewer, 3D actually makes the film an object to look at. The entire notion of 3D actually runs directly counter to the goals of film as a medium.

So if 3D isn’t the future of film, what is? I believe any advance is going to have to be far more radical. To increase the audience’s sense of immersion is difficult. We already use surround sound to suggest to the audience that they sit in the middle of the film’s world, so perhaps video is next. If there is to be a change in the way we watch movies, it might likely come through an expansion of the screen. Rather than just occupying our direct vision, it will occupy the peripheries as well. Such a change would put an immense burden on the filmmaker, and I think it is, at the very least, unlikely to come soon. But I can imagine a movie going experience in which an audience member may look all the way around himself to experience a movie. Two members of the same audience might have wholly different experiences of the film. One might notice the villain lurking in the background while the other is entirely focused on the protagonist’s actions. It seems a little crazy, and like I said, it would be a production nightmare. But if we are to experience a true paradigm shift in how movies are exhibited, I think it is far more likely it will come along this sort of avenue than a branch of existing 3D technology.