Is it correct to call movies "3D"?

Since Einstein introduced time as the fourth dimension back in his theory of relativity a century ago, and modern physics is pushing those boundaries even further, I can't help but wonder why we still insist on calling these movies "3D" instead of "4D"... if we are actually perceiving all three spatial dimensions along with the progression of time within the frame.
Has the film industry even given this much thought, or are they just sticking to outdated terminology?

😁 I suppose this primarily pertains to how the cinematic imagery is perceived, given that a 3D image can certainly be static in nature.
And how might one account for those gimmicky experiences, such as 4DX or 6D theaters?

I'm pretty sure 4DX is just those seats that shake and rattle... But this "6D" thing? What is that, does it spray fart smells in your face or something? 🤔

I think they’re primarily talking about how you perceive the image itself, since a 3D image can technically be static...

If that's the case, then the logic is fundamentally flawed because a movie is essentially a sequence of frames changing over time—we're talking anywhere from 23.976 to 25 frames per second... You really can't equate it to a single still image, because at any given moment, there's only one frame being shown.

Mark Cruz15 said:I suppose 4DX is probably just those vibrating seats. But what on earth would 6D even be? Does it involve smelling farts or something? 🤔

😁 Well, I guess she's right. Along with the shaking seats, they include scents, water sprays, wind effects, and things of that nature...

And what about those movies set in deep space or vacuums?
The audience won't be able to breathe because they'll suck all the oxygen right out of the room... that’s basically 14D technology for you.
Ticket sales are tanking, apparently.

Mark Cruz15 said:Since Einstein introduced time as the 4th dimension in his theory of relativity a century ago, and modern physics is pushing even further, why do we call these movies 3D instead of 4D? We see all three spatial dimensions plus the passage of time...

Compared to a "2D" presentation, 3D films show depth...
But that depth isn't an inherent characteristic of the film itself (the surface of the film strip doesn't have any relief, let alone some complex 3D shape).
Essentially, the "third D" is provided by the audience, not the film itself.

As for the fourth dimension...
In the realm of cinema, Austin holds zero authority. I don't understand the need to be a lid for every (literally every single one) pot!
...meaning, regarding the fourth dimension, the time within the plot is not one of the dimensions being discussed here.

By that logic, you can't credit a 2D film with three-dimensionality just because of the hour and a half spent in a projector—I know, it sounds harsh, but those are the rules.

A 3D film is just a 2D film filmed in a specific way... plus that trivial fourth dimension called
'aging, regardless of where you are or what you do'.
And that doesn't count, because people love to attach it even to the oldest films shot in black and white, which remain strictly 2D.

To reiterate: the 'third D' is the audience.

Has the film industry even considered this?

We considered it—that’s why it is what it is.

coppersailor28 said:Compared to what people call "2D" viewing, 3D movies actually present depth...
But that depth isn't an inherent property of the movie itself (the surface of a film strip doesn't have any topographical relief, let alone some complex 3D shape).
So, essentially, for that "third D" it is the audience who is responsible, not the film as a standalone entity.

Look, I know what a 3D movie is; I've been to plenty of them at the local theater.

As far as the fourth dimension goes...
when it comes to cinema, Austin isn't exactly some supreme authority. I honestly don't get why there's this constant need to be the lid on every single (and I mean every single) pot!
...meaning, regarding the fourth dimension, the passage of time within the plot isn't one of the dimensions we're discussing here.

By that same logic, you wouldn't credit a 2D film with being three-dimensional just because of the hour and a half spent running through a projector—I know, sounds harsh, but those are the rules.

A 3D film is just a 2D film captured in a very specific way... plus that trivial fourth dimension known as
'aging, regardless of where you are or what you do'.
And that doesn't count, because people love to tack that onto even the oldest films, the ones shot in black and white, which are still just 2D despite everything else.

Let me repeat: the 'third D' is the audience.

We thought about it—so that's how it is.

In short, it's called that simply because you all decided it should be. ☕

So, Einstein called time the 4th dimension just to make his theory of relativity make sense—but that doesn't mean time is actually a dimension, or even that it exists at all on a fundamental level. This video breaks it down pretty well: Is Time Real?
Anyway, enough with the physics talk... even if we pretend time *is* a dimension, when people sit down to watch a movie, they already know the plot is unfolding over time. I mean, that’s literally what a movie is. So, I guess you could say the whole concept of time is basically baked into the word "movie" itself.

I don't know, I feel like when people say '3D' regarding movies, they're really just talking about that emphasized sense of depth. It’s that extra layer of spatial dimension that stands out in those films, so I don't see any real issue with how they name it. Space has multiple dimensions, and '3D' just gives the audience a heightened experience of that third dimension—depth.

Since time is qualitatively different from space, if we actually wanted to bring time into the conversation, it would be more accurate to call it a '3+1' dimension. In that light, time acts as the 'fourth' dimension. Otherwise, a fourth dimension would technically just be another spatial one, like with a tesseract. But honestly, we're mostly dealing with marketing terms here. Scientific precision usually takes a backseat to names that are catchy and easy to remember.

Mark Cruz15 said:I know what a 3D movie is. I've sat through a few in theaters.
In short, That's exactly why it's called that. What exactly have you all decided? ☕

Well...
I'm not even looking at the reasoning behind that name from that perspective:

- Just a regular photo. (photo) If we’re talking about 2D, that third dimension—the one actually "making" the image—only spans a few microns. It's negligible. There is zero point in factoring in paper thickness.

- 3D imagery. (image) It’s 2D. The relevant third dimension—specifically the one that... etc.

- Just an ordinary movie. It’s just 2D. The relevant third dimension—specifically, the one that... etc.

- 3D films. A gimmick. Most of them are just an excuse to charge extra for a blurry, headache-inducing mess. If the tech actually worked, we wouldn't be sitting there feeling like our eyes are being pulled in two different directions. It’s all flash, no substance. It's just 2D. The relevant third dimension—specifically the one that... etc.

3D image. (photo) It's a 2D image. Photographed and processed. Added an upper plate, for example. In a unique way. The finishing details aren't uniform, nor are they relevant here.

3D film is just a 2D film that’s been shot and processed. That's it. (glasses, e.g.) In a unique way. The finishing details aren't uniform. They don't matter here.

3D films. A gimmick. Most of them are just an excuse to charge more for a ticket while making everyone in the theater squint at the screen. Give me actual cinematography over cheap depth effects any day. It’s the same deal with 3D photography. I am inherently 2D.
The third dimension. (depth) Only a human would actually "notice" a film like that. Let's release a few—if any—of the other animals..
That third dimension is nothing more than an illusion.Not even a real dimension. It isn't like a spatial third dimension, nor is it anything like time, what people call the fourth dimension..

It’s a deliberate and successful deception. These 2D films utilize specific filming or projection techniques to create the illusion of 3D space. Calling them 3D movies isn't wrong.

Mark Cruz15 said:Considering the circumstances. If Einstein had integrated his theory of relativity into the mainstream a century ago. Time as a fourth dimension. Simple concept. Most people struggle to grasp it. They view it as a linear progression, a simple ticking clock. It isn't. If you want to understand the physics, you have to look at it through the lens of the theory of relativity. Time isn't just a background setting; it's an integral part of the fabric of our universe. A fourth dimension. Deal with it.And today. Physics. It goes even further., Why? That’s what they call those movies. 3D., Not 4D., Since. We see all three spatial dimensions and the flow of time within them.?
Has the film industry even considered this?

Mark Cruz15 said:Since Einstein introduced time as the fourth dimension in his theory of relativity over a century ago—and modern physics is pushing even further—why do we still call these movies 3D instead of 4D? I mean, we're seeing all three spatial dimensions plus the progression of time, right?
Has the film industry even given this any thought?

Why would you expect the film industry to care about physics or Einstein? They didn't come up with these names in a lab—it’s just marketing and sales tactics from an industry filled with people who aren't physicists.

There are three spatial dimensions: width, height, and depth.
Standard 2D films have width and height, whereas 3D films "possess" that third dimension (depth)—and for the sake of this argument, it doesn't matter that the effect is artificially created through technical tricks.

steeljackal7 said:Why on earth would filmmakers even need to care about physics or Einstein in the first place? ...

👍 That's precisely the point. The industry gave it the name '3D film' for a reason.

It's like getting a city code enforcement officer worked up because a street in Washington, D.C. is named Beethoven Street, even though that composer never set foot in the city...

(Meanwhile, there's a Ford Fusion covered in graffiti right on that same street—but no, that's not his concern. His only concern is "is it technically correct to call this Beethoven Street?!")

Why should the film industry bother following any basic principles? Film, photography, pottery, sculpture, painting... it’s all art. And as art, it creates its own culture and set of rules. As coppersailor28 explained, though I'll just offer my own take here:

Sculpture: 3D

Photography/Painting: 2D

Standard film: 2D

3D film: 3D

3D photography: 3D

Dimensions—and how different scientific fields actually apply them—are totally different things. Here is what my Wikipedia says:

- Physics: coordinate systems
- Mechanics: width, length, and height
- Math (and sometimes physics): uses an imaginary 2D space
- Einstein's theory of relativity: width, length, height, and time

So, if every branch of science interprets the same data however it wants, why shouldn't art be the same? Art uses its own principles, and that's really what allows it to exist in the first place.

It’s only natural that when you make a movie, you get a 2D film, or when you take a photo, you get a 2D image. When you add that extra "dimension" to a film, it automatically becomes a 3D movie. At the end of the day, time—just like sound—is simply an element of film...