What Is the Difference between 3D and 2D?

Alan Rankin

The terms "three-dimensional" (3D or 3-D) and "two-dimensional" (2D or 2-D) are most commonly used in reference to photography and other graphic image technology, such as animation and computer graphics. The difference between 3D and 2D images is that 3D images add the perception of depth. A 2D image, on the other hand, has only height and width. The term "three-dimensional" also is sometimes used to describe a physical item such as a sculpture or mobile, which could be described as three-dimensional art, in comparison with a two-dimensional painting.

During the 1950s, Hollywood filmmakers made many 3D movies.
During the 1950s, Hollywood filmmakers made many 3D movies.

Three-dimensional imagery cannot be created without duplicating the effect of two eyes working in tandem, which allows three-dimensional perceptive effects such as depth perception. Early 3D technology imitated this process with dual-camera or dual-lens setups. Modern computer technology can easily create realistic effects in both 3D and 2D.

Audiences must wear special glasses in order to see the illusion of depth in a 3D movie.
Audiences must wear special glasses in order to see the illusion of depth in a 3D movie.

Photography records images for reproduction on flat, two-dimensional surfaces, such as paper prints or display screens. This has the effect of flattening the image, reducing or eliminating the effect of depth. Natural vision produces this effect because the eyes are set slightly apart, allowing the brain to process two different views of the same image. During the late 19th century, photographers attempted to rectify this problem with dual still and motion cameras that were designed to work in tandem. Viewing these “stereoscopic” images through special viewers simulated the effect of seeing a three-dimensional image.

The terms 3D and 2D first came into popular use because of the film industry. During the 1950s, Hollywood filmmakers experimented with 3D movies as a marketing gimmick. These movies were filmed with a variation on the stereoscopic dual-camera setups. They were expensive to produce and required viewers to wear special glasses to experience the 3D effect. Only a few of these movies became lasting classics, most in the horror/suspense genre, such as House of Wax, Creature from the Black Lagoon and Alfred Hitchcock’s Dial M for Murder.

A second wave of 3D films in the 1980s had similar results. The earliest video games, meanwhile, also had 2D graphics, but in the 1980s and 1990s, rapid advances in computer processing and memory made more realistic images possible. By the 21st century, computer-generated imagery (CGI) could create 3D and 2D effects for big and small screens alike. In 2009, James Cameron’s film Avatar pioneered a new wave of cinematic 3D by combining cutting-edge CGI and digital filmmaking technology. Soon, many of Hollywood’s big-budget effects films were following suit.

In real life, there is another crucial difference between 3D and 2D vision. Three-dimensional vision contributes to depth perception, or the ability to estimate an object’s distance. This fact has been humorously pointed out on the science fiction television series Futurama because one of the show’s main characters, Leela, has only one eye. Despite being the pilot of an interstellar space ship, Leela often complains that she has no depth perception. Ironically, Andre de Toth, the director of the famous 3D film House of Wax, also had only one eye, and he could not see in 3D.

Many printers can now print objects in three dimensions.
Many printers can now print objects in three dimensions.

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Discussion Comments

@RoyalSpyder: While it’s true that technology has advanced over the years, computer animation still requires a lot of work and effort. Animating the characters themselves is very time consuming. They have to be modeled, and their movements and facial expressions have to be pinpointed. On top of that, creating the hair for the characters is a grueling process.

As an example, in Pixar’s “Brave”, new technology had to be created to animate Princess Merida’s hair. It pushed the limits of what Pixar previously accomplished. On a final note, there’s more to a movie than just animating it. Script, direction, casting and tone are also important factors; essential parts of a whole. You really have to appreciate the lengths the animators and producers go to ensure quality films for their audience.


In relation to this article (as it discusses differences between 2D and 3D), it got me thinking about movies in this day and age, namely from Pixar and DreamWorks. With the technology that we have, why does it take years to make computer animated movies? After all, it’s not like everything has to be hand drawn, right?


@bythewell - Actually, making animated films is just generally time consuming and takes a lot of man-power so I imagine that adding a 3D effect can cost quite a bit.

I think that they tend to make a lot from the 3D versions though, because people will pay a lot for that kind of experience.


@pastanaga - In my experience the films that really do 3D well are the ones that were animated in the first place, because the computer doesn't have to mess around with real actors and knows exactly what each scene would have looked like from multiple perspectives.

They can also make up incredible landscapes and make full use of 3D since there are no limitations in a digital world.

I imagine the 2D to 3D conversion isn't difficult or particularly time consuming either.


I know that computers can create a kind of 2D to 3D effect after a film has been shot, but I don't think it's as good as using two real cameras to film from both angles. I find that films where they have just added a 3D effect after the fact tend to look like cardboard cutouts, rather than real 3D, and, frankly, there is usually not much point to the 3D anyway, because the scene wasn't filmed with that effect in mind.

If you want to see an amazing example of proper 3D filming, Coraline is a really good one. Since it was made with claymation rather than live actors, they were easily able to capture proper 3D and many of the scenes use that to full effect.

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